Journal articles on the topic 'Cartography Computer simulation'

Cerebral cartography can be understood in a limited, static, neuroanatomical sense. Temporal information from electrical recordings contributes information on regional interactions adding a functional dimension. Selective tagging and imaging of molecules adds biochemical contributions. Cartographic detail can also be correlated with normal or abnormal psychological or behavioural data. Modern cerebral cartography is assimilating all these elements. Cartographers continue to collect ever more precise data in the hope that general principles of organization will emerge. However, even detailed cartographic data cannot generate knowledge without a multi-scale framework making it possible to relate individual observations and discoveries. We propose that, in the next quarter century, advances in cartography will result in progressively more accurate drafts of a data-led, multi-scale model of human brain structure and function. These blueprints will result from analysis of large volumes of neuroscientific and clinical data, by a process of reconstruction, modelling and simulation. This strategy will capitalize on remarkable recent developments in informatics and computer science and on the existence of much existing, addressable data and prior, though fragmented, knowledge. The models will instantiate principles that govern how the brain is organized at different levels and how different spatio-temporal scales relate to each other in an organ-centred context.

<p><strong>Abstract.</strong> Since its establishment in 1807, the National Oceanic and Atmospheric Administration’s (NOAA) Office of Coast Survey has provided nautical charts to support safe shipping, national defence, and the delamination of maritime boundaries. The mission of the office is to provide navigation products and services that ensure safe and efficient maritime commerce on America’s oceans and coastal waters, and in the Great Lakes. The Office of Coast Survey employs cartographers, hydrographers, physical scientists, managers and administrative staff in order to fulfil its mission. Until recently, training in nautical cartography at the office of Coast Survey was conducted at the branch level and differed based on level of employee seniority (i.e., Entry, Intermediate and Advanced) and the processing branch of the employee. Over the past two years, NOAA has established a Coast Survey CAT B program that is intended to train and educate to up to 13 cartographers per year in nautical cartography, through a combination of lectures, hands-on chart production experience, details to various branches within the Coast Survey, and field trips to working hydrographic survey vessels through six training modules spread over a one-year period, spread over six courses that include:</p><ul><li><i>Refresher course</i> that provides a review of the basic math, computer and communication technology, marine geography, hydrography, and geodetic topics. The goal of this course is to ensure that students have a sufficient academic background to succeed in the subsequent CAT-B program courses and other activities.</li><li><i>Introduction to Cartography course</i> that reviews elements of cartography, specifically scale, design, and data manipulation techniques. Students will gain an appreciation for maps and map-making, including manual techniques. This introductory course will include hands-on use of computer graphics tools.</li><li><i>Map Design course</i> that reviews the various styles and techniques associated with cartographic design. The course will require the student to: 1) analyse chart design parameters, 2) compile thematic cartographic projects, and 3) experiment with map design.</li><li><i>GIS and Spatial Analysis course</i> that provides students with a comprehensive understanding of spatial analysis methods and they will learn practical skills in using GIS and spatial analysis. The class covers the methods of spatial analysis including measuring aspects of geometric features and identifying spatial patterns of geospatial objects that are represented as point, line, network, areal data, and 3-D surfaces.</li><li><i>GIS and Spatial Modelling course</i> that provides the students a foundation and understanding of various issues related to modelling and simulation in the GIS. It will address the concepts, tools, and techniques of GIS modelling (vector- and raster-based modelling). In addition, it will present modelling concepts and theory as well as provide opportunities for hands-on model design, construction, and application.</li><li><i>NOAA training project and internship program course</i> that includes: 1) a detailed review of many of the activities conducted by the branches in NOAA’s Marine Chart Division and 2) a training project that demonstrates the student’s ability to implement the knowledge gained during the certification.</li></ul><p>This paper presents a newly established CAT B certificate program in Standards of Competence for Nautical Cartographers that is conducted at NOAA’s main campus in Silver Spring, Maryland, USA. The CAT B certificate program provides NOAA a mechanism to both enhance building capacity within the organization and recognizing NOAA cartographers for their capabilities and efforts. In addition, such a program at NOAA can also be used to recruit new employees and help to build capacity in sister organizations.</p>

<p><strong>Abstract.</strong> The paper considers three scientific approaches and outlines a new concept of systematic cartography.</p><p>The first approach &amp;ndash; systems theory</p><p>Systems theory has long been concerned with the study of complex systems (in recent times, complexity theory and complex systems have also been used as names of the field). Complex systems are present in the research of various disciplines, including geosciences, economics, social studies and technology. Recently, complexity has become a natural domain of interest in real-world socio-cognitive systems and emerging systemics research. Complex systems tend to be high-dimensional, non-linear, and challenging to study. Organised complexity is the degree of both the organisation and complexity of a system. When organisation and complexity are not part of the same system they each undoubtedly can occur naturally, but when both organisation and complexity are found in the same system, the odds of their occurring drop considerably, and the more of both that a system has, the less probable it becomes.</p><p>It is often useful to consider spatial problems through a general systems approach. A general system is a group of fundamental elements bound together by specific linkages. Systems may be open or closed and may change through time. The earth is an open system in which there are inputs, outputs, and flow-through mechanisms. The linkages, or connections, that bind entities together into a system are paths through which matter, energy, ideas, and people pass from one element to another. General Systems Theory is useful to any approaches describing the earth &amp;ndash; cartography is one of them.</p><p>Cartography employs systems to develop analytical models with which they seek to understand and explain spatial patterns and interactions. Cartographers use the systems model, for example, to examine human migration patterns, the diffusion of ideas, and the spread of information. Moreover, research about maps relies on understanding the systems in which information and communication processes operate. Cartographers are interested in identifying, explaining, and predicting information flows in maps. They also seek to identify, describe, and explain cycles and patterns in both maps and map collections.</p><p>The second approach &amp;ndash; atlases</p><p>Atlases are, probably, the best known and the most flexible of popular cartographic products. Atlases are used to address different issues and to target different audiences. Historically, atlases have played different roles &amp;ndash; from instruments of power, in the Renaissance to a current decision and planning support tools. Atlases are used for general reference, education, research and business. As they evolved, atlases were produced in different ways, from the initial manual compilation to current computer-generated processing. Atlases have experienced many changes in the way they are conceived, produced, disseminated and used.</p><p>Many definitions of an atlas exist, and all of them involve words “systematic collection” or similar expression that an atlas is not a set of map randomly chosen maps and their random arrangement as a book. After a rapid ICT development provides fast map compilations, it seems that atlas cartography is much more comfortable. Various types of atlases can be distinguished by the region, theme, dissemination concept, presentation medium and interaction with users. All these kinds of atlases share the overall objective to communicate geographic knowledge and facilitate new insight into geographic phenomena.</p><p>The third approach &amp;ndash; Tobler's first law of geography</p><p>The Tobler's first law of geography was introduced into the geographical literature in an article that Waldo Tobler (1930&amp;ndash;2018) published in the journal Economic Geography in 1970. He described a simulation of population growth in Detroit and invoked the law: “everything is related to everything else, but near things are more related than distant things.”</p><p>It considers the following questions for cartographers: Can the Tobler's law be applied in cartography when we replace objects with maps? How can “near” and “distant” be measured in an atlas? Is it right for Euclidean and network space?</p><p>A concept of systematic cartography</p><p>Systematic cartography is a set of interrelated approaches for visualising a wide range of spatial data sources by various techniques. A traditional field of systematic geovizualisation is the atlas production. At present, advanced display techniques and distributed spatial data sources multiply the possibilities and range of visualization outputs. A theoretical systematic approach plays a crucial role for content, designing, compilation and symbology of any atlas. This calls for the implementation of system theory into an atlas conceptualisation.</p><p>Can atlas be described as a system? If a system consists of elements and relationships between them, then an atlas consists of maps and relationships between them. As a system has a structure and behaviour, an atlas has a structure and usage. In the system theory, a system has a language (information is passed through the information channels). In systematic cartography, an atlas passes spatial information through map language. If we describe an atlas as a system we might measure atlas and then to improve it, redesign it, reuse it etc.</p><p>If an atlas is a system according to the theory of systems (a system universum A involves maps, symbols, map elements, graphs, texts, etc. and a system characteristics R involves all relationships between them) it make us possible to measure “a rate of systematization”, and make atlas taxonomy better. It will also provide a view into an atlas structure and tools for its imporving. And it is really worth!</p><p>Maps in atlases are organized gradually (i) from simple analytical maps (of the main theme components), (ii) to the complex and synthetic maps, (iii) the content of the thematic atlas is arranged like a storybook, (iv) from simple to complex, (v) from basic information to the culmination as the main message in sense of spatial synthesis (typology and regionalization). The relationships relate to map language either in map series, in atlas structure and design and between maps vs. graphs, tables and figures.</p>

A novel square equal-area map projection is proposed. The projection combines closed-form forward and inverse solutions with relatively low angular distortion and minimal cusps, a combination of properties not manifested by any previously published square equal-area projection. Thus, the new projection has lower angular distortion than any previously published square equal-area projection with a closed-form solution. Utilizing a quincuncial arrangement, the new projection places the north pole at the center of the square and divides the south pole between its four corners; the projection can be seamlessly tiled. The existence of closed-form solutions makes the projection suitable for real-time visualization applications, both in cartography and in other areas, such as for the display of panoramic images.

Conventional proactive routing protocols, due to their inherent nature based on shortest paths, select longer links which are amenable to rapid breakages as nodes move around. In this paper, we propose a novel adaptive probabilistic approach to handle routing information in dense mobile ad hoc networks in a way to improve the proactive routing pertinence as a function of network dynamics. We first propose a new proactive routing framework based on probabilistic decisions and a generic model to compute the existence probabilities of nodes and links. Then, we present a distributed algorithm to collect the cartography of the network. This cartography is used to instantiate the existence probabilities. Conducted simulations show that our proposal yields substantially better routing validity. Nonetheless, it amounts to much longer routes. We proposed then a bounding technique to adapt and overcome this side effect and defined two probabilistic proactive routing variants. Conducted simulations show that our proposed bounded probabilistic proactive routing schemes outperform conventional routing protocols and yield up to 66 percent increase in throughput.

The article deals with the actual issue of arranging the process and the system of cartographic support. The authors generalize production and publication of cartographic products only. Within the framework of issuing, the process of production and publishing cartographic products is considered as functioning of a purposeful cartographic support system. During these studies, the vector of production process quality indicators results and publishing cartographic products is justifi ed. The proposed indicators enable predicting the results of the process under consideration. Based on the vector of quality indicators, the operational functional connecting the performance indicator with the cost of resources and time is justifi ed. The purposeful process’ of producing and publishing cartographic products deterministic model is proposed. With its use the simulation was performed. The results help determining the mapping support system contents based on the tasks set.

Contemporary development of computer hardware and software, WebGIS and geo-web services as well as the availability of semantic 3D city models, facilitate flexible and dynamic implementation of web applications. The aim of this paper is to introduce 4D CANVAS, a web-based application for dynamic visualization of 3D geospatial data for improved decision making in smart city applications. It is based on the Cesium Virtual Globe, an open-source JavaScript library developed with HTML5 and WebGL. At first, different data formats such as JSON, GeoJSON, Cesium Markup Language (CZML) and 3D Tiles are evaluated for their suitability in 4D visualization applications. Then, an interactive Graphical User Interface (GUI) is built observing the principle of cartographic standards to view, manage, understand and explore different simulation outputs at multiple spatial (3D surface of buildings) and temporal (hourly, daily, monthly) resolutions. In this regard, multiple tools such as aggregation, data classification, etc. are developed utilizing JavaScript libraries. As a proof of concept, two energy simulations and their outputs of different spatial and temporal resolutions are demonstrated in five Asian and European cities. Finally, the 4D CANVAS is deployed both in desktop and multi-touch screens. The proposed application allows easy integration of any other geospatial simulation results, thereby helps the users from different sectors to explore them interactively in 4D.

In this paper, the authors propose a novel routing protocol driven by an asynchronous distributed cartography gathering algorithm. Each node senses its own dynamics and chooses locally an appropriate routing period size. As such stationary nodes generate little signaling traffic; fast moving nodes choose small routing periods to mitigate the effect of their mobility. Moreover, every node integrates a self regulating process that dynamically and constantly calibrates the chosen routing period to track changes in its dynamics. The performances of this proposed routing protocol are evaluated and compared to the known Optimized Link State Routing (OLSR) protocol through extensive simulations. The paper shows that the collected network cartography maintains a validity ratio near 100% even for high node speeds. The authors illustrate that the proposed routing protocol provides around 97% routing validity while the OLSR can hardly deliver more than 60% at moderate to high speeds and workloads. Finally, the protocol provides better throughput than OLSR, reaching a 50% increase at moderate to high speeds and workloads far less end-to-end delays.

Abstract. Satellite retrievals of methane weighted atmospheric columns are assimilated within a Bayesian inversion system to infer the global and regional methane emissions and sinks for the period August 2009 to July 2010. Inversions are independently computed from three different space-borne observing systems and one surface observing system under several hypotheses for prior-flux and observation errors. Posterior methane emissions are compared and evaluated against surface mole fraction observations via a chemistry-transport model. Apart from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY), the simulations agree fairly well with the surface mole fractions. The most consistent configurations of this study using TANSO-FTS (Thermal And Near infrared Sensor for carbon Observation – Fourier Transform Spectrometer), IASI (Infrared Atmospheric Sounding Interferometer) or surface measurements induce posterior methane global emissions of, respectively, 565 ± 21 Tg yr−1, 549 ± 36 Tg yr−1 and 538 ± 15 Tg yr−1 over the one-year period August 2009–July 2010. This consistency between the satellite retrievals (apart from SCIAMACHY) and independent surface measurements is promising for future improvement of CH4 emission estimates by atmospheric inversions.

Agricultural energy consumption is an important environmental and social issue. Several diagnosis tools have been proposed to define indicators for analyzing the large-scale energy consumption of agricultural farm activities (year, farm, production activity, etc.). In Bimonte, Boulil, Chanet and Pradel (2012), the authors define (i) new appropriate indicators to analyze agricultural farm energy-use performance on a detailed scale and (ii) show how Spatial Data Warehouse (SDW) and Spatial OnLine Analytical Processing (SOLAP) GeoBusiness Intelligence (GeoBI) technologies can be used to represent, store, and analyze these indicators by simultaneously producing graphical and cartographic reports. These GeoBI technologies allow for the analysis of huge volumes of georeferenced data by providing aggregated numerical values visualized by means of interactive tabular, graphical, and cartographic displays. However, existing data collection systems based on sensors are not well adapted for agricultural data. In this paper, the authors show the global architecture of our GeoBI solution and highlight the data collection process based on agricultural ad hoc sensor networks, the associated transformation and cleaning operations performed by means of Spatial Extract Transform Load (ETL) tools, and a new implementation of the system using a web-services-based loosely coupled SOLAP architecture to provide interoperability and reusability of the complex multi-tier GeoBI architecture. Moreover, the authors detail how the energy-use diagnosis tool proposed in Bimonte, Boulil, Chanet and Pradel (2012) theoretically fits with the sensor data and the SOLAP approach.

Vector arithmetic is a base of (coordinate) geometry, physics and various other disciplines. The usual method is based on Cartesian coordinate-system which fits both to continuous plane/space and digital rectangular-grids. The triangular grid is also regular, but it is not a point lattice: it is not closed under vector-addition, which gives a challenge. The points of the triangular grid are represented by zero-sum and one-sum coordinate-triplets keeping the symmetry of the grid and reflecting the orientations of the triangles. This system is expanded to the plane using restrictions like, at least one of the coordinates is an integer and the sum of the three coordinates is in the interval [−1,1]. However, the vector arithmetic is still not straightforward; by purely adding two such vectors the result may not fulfill the above conditions. On the other hand, for various applications of digital grids, e.g., in image processing, cartography and physical simulations, one needs to do vector arithmetic. In this paper, we provide formulae that give the sum, difference and scalar product of vectors of the continuous coordinate system. Our work is essential for applications, e.g., to compute discrete rotations or interpolations of images on the triangular grid.

A combination of Internet of Things and multiple robots with sensors has been an attractive research topic over the past years. This article proposes an Internet of Robotic Things system structure to monitor events, fuse sensor data, use local robots to determine a best action, and then act to control multiple mobile robots. The Internet of Robotic Things system includes two main layers: the host controller layer and the multiple robots layer. The controller layer communicates with the multiple robots layer by Wi-Fi module. The Internet of Robotic Things system helps finish five tasks: localizing robots, planning paths, avoiding obstacles, moving to waypoint stable, and creating a map. Based on depth data from depth camera and robot posture, a mapping algorithm is proposed to create map. Based on light detection and ranging sensor data and google cartographer, simultaneously localization and mapping (SLAM) is also processed in this article. The fuzzy sliding mode tracking control method is proposed for each robot to guarantee the robot stable moves. Simulation results show the effectiveness of the proposed algorithm and are used to compare with the experiment result. In the experiment, one host computer and two Kobuki mobile robots with light detection and ranging and depth camera sensors are integrated as an Internet of Robotic Things system. Two robots successfully localize themselves and avoid obstacles. The follower robot simultaneously builds a map.

Abstract: In many countries, the positional accuracy control by points in Cartography or Spatial data corresponds to the comparison between sets of coordinates of well-defined points in relation to the same set of points from a more accurate source. Usually, each country determines a maximum number of points which could present error values above a pre-established threshold. In many cases, the standards define the sample size as 20 points, with no more consideration, and fix this threshold in 10% of the sample. However, the sampling dimension (n), considering the statistical risk, especially when the percentages of outliers are around 10%, can lead to a producer risk (to reject a good map) and a user risk (to accept a bad map). This article analyzes this issue and allows defining the sampling dimension considering the risk of the producer and of the user. As a tool, a program developed by us allows defining the sample size according to the risk that the producer / user can or wants to assume. This analysis uses 600 control points, each of them with a known error. We performed the simulations with a sample size of 20 points (n) and calculate the associated risk. Then we changed the value of (n), using smaller and larger sizes, calculating for each situation the associated risk both for the user and for the producer. The computer program developed draws the operational curves or risk curves, which considers three parameters: the number of control points; the number of iterations to create the curves; and the percentage of control points above the threshold, that can be the Brazilian standard or other parameters from different countries. Several graphs and tables are presented which were created with different parameters, leading to a better decision both for the user and for the producer, as well as to open possibilities for other simulations and researches in the future.

Nuclear safety has always been a focal point in the field of nuclear applications. Mobile robots carrying specific sensors for nuclear-radiation detection have become an alternative to manual detection. This work presents an autonomous α/β radiation mapping framework, using a mobile robot carrying a light detection and ranging (LiDAR) and a nuclear-radiation-detection sensor. The method employs simultaneous localization and mapping (SLAM) techniques and radiation-detection sensors. Cartographer is adopted as a demonstration example to map the unknown environment. Radiation data are obtained through the radiation detection sensor and projected onto the environment map after coordinate alignment. The color-coded radiation map is shown on the environment map according to the dose rate. The simulation and real-environment experiments in a robot-operating system (ROS) validate the effectiveness of the proposed method in different radiation scenarios for both indoor and outdoor environments.

The paper provides a study on the watermarking method for vector map data based on a cyclic shift of a polygon vertex list. We propose a method modification allowing to automate authentication procedure, as well as to increase robustness against map contents modification. The main idea of the improved method is to use a noise-like image as a secondary carrier for a watermark, represented in the form of a bit sequence. An algorithm for construction of a noise-like image carrying a watermark sequence, as well as an algorithm for extraction of such a sequence, are given. An experimental study explores the information capacity of the carrier image and its robustness against quantization and interpolation noise adding, i.e. distortions simulating the embedding into map objects. The efficiency of the method is also demonstrated on real cartographic data. Conclusions comprise recommendations for rational choice of embedding parameters depending on the number of polygons on the vector map.

Dans le cadre de la Recette Thématique Utilisateur pour la valorisation des données Pléiades-THR, des images ont été acquises lors de désastres naturels ou pour des exercices dédiés à la demande des grands services de l'Etat (Ministère de l'Environnement, Ministère des Finances). En sus, ces actions ont eu pour objectif de faciliter la prise de connaissance des technologies spatiales par ces utilisateurs institutionnels français dans un contexte de gestion de crise. En mars et mai 2013, c'est en concertation avec le CNES, le SERTIT, le SCHAPI, l'IGN et le CEREMA que des données Pléiades ont été programmées et traitées en mode rapide lors de la crue de l'Agly et des inondations provoquées par l'Yonne et la Marne. En juin, deux nouvelles actions de cartographie réactive ont été menées par le CNES et le SERTIT : la première avec le Service de Prévision des Crues Rhin-Sarre (DREAL Alsace) lors de la crue de la Sarre, la seconde pour le compte de la Caisse Centrale de Réassurance lors de la crue du Gave de Pau. Enfin, en février, l'exercice « SEISME 13 » a été réalisé à la demande du centre de crise du Ministère de l'Environnement (SG/SDSIE/CMVOA). Il s'agissait d'un exercice cadre d'état-major réalisé sur 2 demi-journées dans le contexte de la simulation d'un séisme d'une magnitude exceptionnelle en Guadeloupe, sur la base d'un scénario technique proposé par le BRGM. Pour chacune de ces opérations, ce sont une à trois images ou segments d'images qui ont été acquis, analysés, dont un couple stéréoscopique, pour la réalisation de produits cartographiques à valeur ajoutée et informations vectorielles.En termes de besoins utilisateurs, les objectifs concernaient la détection des surfaces en eau, des ruptures de digue, des constructions affectées. Dans le cas des crues rapides de l'Agly et du Gave de Pau, l'analyse des données Pléiades a également porté sur la reconnaissance et l'extraction de l'empreinte des inondations, comprenant les surfaces en eau résiduelle, les dépôts de boue et les traces d'écoulement. Dans l'exemple de l'Agly, l'apport des données stéréoscopiques a été testé via la réalisation d'un MNT. Dans la démonstration « SEISME 13 », des produits cartographiques ont été élaborés en réponse aux besoins particuliers exprimés par les Ministères de l'Environnement, des Transports et de la Santé (dégâts aux infrastructures de transport, de production, bâtiments publics).L'ensemble de ces actions de cartographie rapide ont permis de sensibiliser de nouveaux utilisateurs et acteurs majeurs au principe de gestion de crise (processus d'alerte, programmation des satellites, commande des données satellitaires et mise à disposition des produits cartographiques à valeur ajoutée), et de porter à leur connaissance les capacités offertes par la constellation Pléiades-THR. Un objectif à long terme serait de doter ces utilisateurs de capacités nationales, hors du cadre proposé par la Charte Internationale « Espace et Catastrophes Majeures » et du service Emergency du programme Copernicus

Abstract. This paper presents a modeling study aiming at quantifying the possible impact of soil characteristics on the hydrological response of small ungauged catchments in a context of extreme events. The study focuses on the September 2002 event in the Gard region (South-Eastern France), which led to catastrophic flash-floods. The proposed modeling approach is able to take into account rainfall variability and soil profiles variability. Its spatial discretization is determined using Digital Elevation Model (DEM) and a soil map. The model computes infiltration, ponding and vertical soil water distribution, as well as river discharge. The model is set up without any calibration and the soil parameter specification is based on an existing soil database. To perform the simulations, radar rainfall estimations are used at a 1 km2 and 5 min resolution. To specify the soil hydraulic properties, two types of pedotransfer function (PTF) are compared. It is shown that the PTF including information about soil structure reflects better the spatial variability that can be encountered in the field. The study is focused on four small ungauged catchments of less than 10 km2, which experienced casualties. Simulated specific peak discharges are found to be in agreement with estimations from a post-event in situ investigation. Examining the dynamics of simulated infiltration and saturation degrees, two different behaviors are shown which correspond to different runoff production mechanisms that could be encountered within catchments of less than 10 km2. They produce simulated runoff coefficients that evolve in time and highlight the variability of the infiltration capacity of the various soil types. Therefore, we propose a cartography distinguishing between areas prone to saturation excess and areas prone only to infiltration excess mechanisms. The questions raised by this modeling study will be useful to improve field observations, aiming at better understanding runoff generation for these extreme events and examine the possibility for early warning, even in very small ungauged catchments.

Abstract. This paper presents a modeling study aiming at quantifying the possible impact of soil characteristics on the hydrological response of small ungauged catchments in a context of extreme events. The study focuses on the September 2002 event in the Gard region (South-Eastern France), which led to catastrophic flash-floods. The proposed modeling approach is able to take into account rainfall variability and soil profiles variability. Its spatial discretization is determined using Digital Elevation Model (DEM) and a soil map. The model computes infiltration, ponding and vertical soil water distribution, as well as river discharge. In order to be applicable to ungauged catchments, the model is set up without any calibration and the soil parameter specification is based on an existing soil database. The model verification is based on a regional evaluation using 17 estimated discharges obtained from an extensive post-flood investigation. Thus, this approach provides a spatial view of the hydrological response across a large range of scales. To perform the simulations, radar rainfall estimations are used at a 1 km2 and 5 min resolution. To specify the soil hydraulic properties, two types of pedotransfer function (PTF) are compared. It is shown that the PTF including information about soil structure reflects better the spatial variability that can be encountered in the field. The study is focused on four small ungauged catchments of less than 10 km2, which experienced casualties. Simulated specific peak discharges are found to be in agreement with estimations from a post-event in situ investigation. Examining the dynamics of simulated infiltration and saturation degrees, two different behaviors are shown which correspond to different runoff production mechanisms that could be encountered within catchments of less than 10 km2. They produce simulated runoff coefficients that evolve in time and highlight the variability of the infiltration capacity of the various soil types. Therefore, we propose a cartography distinguishing between areas prone to saturation excess and areas prone only to infiltration excess mechanisms. The questions raised by this modeling study will be useful to improve field observations, aiming at better understanding runoff generation for these extreme events and examine the possibility for early warning, even in very small ungauged catchments.

The autonomous positioning of tunneling equipment is the key to intellectualization and robotization of a tunneling face. In this paper, a method based on simultaneous localization and mapping (SLAM) to estimate the body pose of a roadheader and build a navigation map of a roadway is presented. In terms of pose estimation, an RGB-D camera is used to collect images, and a pose calculation model of a roadheader is established based on random sample consensus (RANSAC) and iterative closest point (ICP); constructing a pose graph optimization model with closed-loop constraints. An iterative equation based on Levenberg–Marquadt is derived, which can achieve the optimal estimation of the body pose. In terms of mapping, LiDAR is used to experimentally construct the grid map based on open-source algorithms, such as Gmapping, Cartographer, Karto, and Hector. A point cloud map, octree map, and compound map are experimentally constructed based on the open-source library RTAB-MAP. By setting parameters, such as the expansion radius of an obstacle and the updating frequency of the map, a cost map for the navigation of a roadheader is established. Combined with algorithms, such as Dijskra and timed-elastic-band, simulation experiments show that the combination of octree map and cost map can support global path planning and local obstacle avoidance.

<p><strong>Abstract.</strong> Virtual reality (VR) is a display and control technology that provides an interactive computer-generated three-dimensional environment to a user, often via a Head Mounted Display (HMD). VR delivers an immediate and immersive sensory experience of simulated worlds (which may or may not resemble reality), particularly of environments that might otherwise be physically inaccessible to the user due to their location, scale, time or danger. Although the first VR systems began to emerge in the 1960s, their relevance to cartographic applications has only recently become an explicit focus of research. Moreover, the potential of VR technology to visualize topographic databases has yet to be explored by cartographers.</p><p>In this experiment, we designed a VR application of a fictitious city derived from state 1&amp;thinsp;:&amp;thinsp;10,000 topographic data (Polish Database of Topographic Objects BDOT10k) to test user preferences for 2D or 3D urban geovisualizations. The app allows the user to switch between 2D and 3D representations of buildings in the simulation using a remote controller. This functionality enabled participants of the experiment to freely select 2D or 3D mode and for their preferences to be recorded and measured.</p><p>Our experiment involved two groups, one based in Poland and one in the UK, each comprising 30 participants (students enrolled on a Geography undergraduate course at each author’s institution). Participants performed spatial ability tests to help ensure consistency in the sample and each group was divided into two sub-groups. Participants in the first sub-group were each given a navigation task that required their movement across the simulated city from point A to point B in the shortest possible time. Those in the second sub-group were given the freedom to explore the simulated city without being given a specific navigational task. We then interviewed participants in order to understand their own perception of their experiences in using the app.</p><p>The results indicate the preferences of the two groups and sub-groups of participants. In particular, we establish whether users preferred the 2D mode for the navigational task and the 3D mode for free exploration. The findings suggest how producers of topographic datasets might develop the functionality of their products using VR.</p>

With the rapid growth of underground cable trenches, the corresponding inspections become a heavy burden, and an intelligent inspection robot for automatic examinations in underground cable trenches would be a suitable solution. To achieve this, this paper establishes one new navigation methodology for intelligent inspection robots, especially when applied in complex scenarios and the corresponding hardware. Firstly, to map the underground trenches with higher precision, an improved graph optimization cartographer-SLAM algorithm is proposed, which is based on the combination of depth camera and LIDAR. The depth image is converted into pseudo laser data, and fused with LIDAR data for calibration. Secondly, to overcome the low precision of the Laser odometer due to the uneven ground, an adaptive keyframe selection method is designed. Thirdly, the forward A* model is presented, which has been adjusted in three aspects, including the convergence of node searching, the cost function, and the path smoothness, to adapt to the narrow underground environment for global path planning. Fourthly, to realize dynamic obstacle avoidance, an improved fusion scheme is built to integrate the proposed global path planning algorithm and the dynamic window approach (DWA). In the case study, the simulation experiments showed the advantage of the forward A* algorithm over the state-of-the-art algorithm in both time consumption and the number of inflection points generated, the field tests illustrated the effect of the fusion of depth camera images and LIDAR. Hence, the feasibility of this navigation methodology can be verified, and the average length of path and time consumption decreased by 6.5% and 17.8%, respectively, compared with the traditional methods.

Purpose The purpose of this sudy is to provide a complete optimization-based methodology to design waveguides with metamaterial walls. The present methodology is based on optimization. Indeed, the inverse problems of design are formulated as nonlinear black-box optimization problems with constraints. Two inequality black-box constraints are taken into account as penalized terms that are added to the objective function when the constraints are not satisfied. The numerical steps are done by using a finite element method solver (GetDP). Thus, different optimization software are tested to solve the nonlinear black-box optimization problems such as IPOPT, NLOPT and NOMAD from the Opti ToolBox in MatLab. Design/methodology/approach In this work, a methodology to design waveguides with metamaterial walls is proposed. The aim is to solve an inverse problem to find the best design where the electric field cartography is the closest to an imposed one. Findings The present methodology is applied to solve inverse problems of design and satisfactory results were provided by the three solvers IPOPT, NLOPT and NOMAD. Those numerical experiments show that NOMAD is the most efficient method to optimize the design of those cylindrical waveguide structures with metamaterial walls. Research limitations/implications The model is set to find solutions using a specific pattern of metamaterials. This is promising to take those geometries as variables of the optimization problems. Moreover, in this exploratory work, no constraint on the fabrication limits has been taken into account. Originality/value The originality is to formulate design problems of waveguide with metamaterial walls into optimization problems. These optimization problems are difficult to solve because the objective function and two inequality constraints are computed via a numerical simulation code based on finite element methods. Thus, an original approach based on penalization is implemented and three optimization software are used. Hence, the authors propose an optimization-based methodology and apply to solve two inverse problems of design.

Implementation of groundwater flow and transport numerical models is generally a challenge, time-consuming and financially-demanding task, in charge to specialized modelers and consulting firms. At a later stage, within clearly stated limits of applicability, these models are often expected to be made available to less knowledgeable personnel to support/design and running of predictive simulations within more familiar environments than specialized simulation systems. GIS systems coupled with spatial databases appear to be ideal candidates to address problem above, due to their much wider diffusion and expertise availability. Current paper discusses the issue from a tight-coupling architecture perspective, aimed at integration of spatial databases, GIS and numerical simulation engines, addressing both observed and computed data management, retrieval and spatio-temporal analysis issues. Observed data can be migrated to the central database repository and then used to set up transient simulation conditions in the background, at run time, while limiting additional complexity and integrity failure risks as data duplication during data transfer through proprietary file formats. Similarly, simulation scenarios can be set up in a familiar GIS system and stored to spatial database for later reference. As numerical engine is tightly coupled with the GIS, simulations can be run within the environment and results themselves saved to the database. Further tasks, as spatio-temporal analysis (i.e. for postcalibration auditing scopes), cartography production and geovisualization, can then be addressed using traditional GIS tools. Benefits of such an approach include more effective data management practices, integration and availability of modeling facilities in a familiar environment, streamlining spatial analysis processes and geovisualization requirements for the non-modelers community. Major drawbacks include limited 3D and time-dependent support in traditional GIS, and lack of dedicated calibration, analysis and visualization tools. A system implementation based upon ESRI geodatabase, ArcGIS and state-of-the-art finite element 3D flow and transport numerical code Feflow is presented and critically assessed.

Released in 2012 as an Android only open-beta, Ingress is an alternate-reality game for mobile devices. Developed by Niantic Labs, a subsidiary of Google, Ingress now has 7 million users worldwide (Ingress) on both Android and Apple operating systems. Players are aligned to one of two opposing factions, the Resistance (Blue) and the Enlightened (Green). Working on behalf of their faction, individual players interact with “portals” in order to establish dominance over material environments. Portals are located at places of educational or historical value, public artworks, “hyper-local” locations, public libraries, and also places of worship (Google, “Candidate Portal Criteria”). Players take on the role of portal creators, submitting potential portals to the game developers after confirming their location in the game (Google, “New Portal Submissions”).Portals become the primary point of interaction for players, bridging the digital world of the game with the players’ surrounding material environments. Players may gain inventory by hacking portals in order to destroy and (re)claim portals. Territories are claimed by forging links between fully developed portals in order to establish control fields. Portals play an important part not only of the game but in situating the practice of play within the larger sociocultural and material framework of the urban environment. Players navigate their material environment, using portals and digital representations of such spaces alongside their existing knowledge of local environments, to engage with their immediate location as efficiently as possible. While numerous public landmarks are currently used as portals, the primary interest of this paper is the role street art plays within the game, and within the larger practice of curating the city. This paper addresses the practice of playing Ingress as a form of situated play—that is, the notion that play is underscored by sociocultural and material circumstance, while simultaneously contributing to a new shared understanding of what constitutes urban play and the conditions that underscore it. In doing so, this paper firstly addresses the notion of play as a situated practice, mobilising concepts from the field of human–computer interaction as well as cultural studies analyses of games and gaming culture. This framework is applied to the practice of playing Ingress with specific focus on the role street art has in the practice of playing. The discussion of urban play as a means of exhibiting street art is extended to discuss the cultural practice of street art itself, with both occupying the liminal space struggle over the functionality of public space. Both practices occupy this liminal space between subversive use of urban environments and a form of legitimate art—a debate which has been central to forms of urban gaming. By focusing on the role of street art in urban mobile gaming, this paper addresses the cultural function of both practices, while addressing larger questions of curatorship within the urban environment. That is: how can the practice of play, as informed by the practice of street art, be thought of as a means of curating urban spaces? This paper goes on to argue that the practice of urban play may be viewed as a form of curation via the practice of re-reading, re-mixing, and re-mediating urban environments—establishing a new shared understanding of street art, urban environments, and urban play. In this paper I argue that urban mobile games such as Ingress are best thought of as a situated practice. The idea of situated practice is drawn from the fields of game studies and human–computer interaction, and the concept of situated learning. Firstly, situated practice draws from the concept of situated gaming, a term established by Yates and Littleton to understand the cultural niches in which video gaming takes place. For Yates and Littleton, these cultural niches arise from an interaction between gaming, gamers, and gaming culture—all of which are discursively constructed and culturally relative practices. Apperley (Gaming) expands on these ideas to define situated gaming as, firstly, an inclusion of the materiality of embodied gaming experiences and, secondly, an intersection of local gaming cultures and a larger global gaming ecology. Drawing from Suchman’s concept of situated actions, such interactions with technology must be understood as contextualised within specific sociocultural and material circumstances. Dourish expands on Suchman’s work and suggests thinking less about these contexts and more on the practice of technological engagement, of making meaning out of our interaction with technology. This use of “practice” is influenced by the work of Lave and Wenger, who situate learning within a social setting, what they term a “community of practice”. In short, then, the act of playing Ingress is not only an interaction with underlying sociocultural and material circumstance which constitute the urban and play but also a process of generating a shared understanding of both the urban and play within this specific context.Fig. 1: A view of Ingress’s map showing nearby portal using navigation function.Playing with Street Art Ingress functions foremost as a form of urban play; it is a mobile game with location-aware capabilities. The practice of playing games within urban environments is often compared to historically situated forms of urban exploration, such as the Situationist International practice of dérive—a form of urban drifting that is often compared to contemporary forms of mobile-mediated urban play (de Souza e Silva and Hjorth; Flanagan; Stevens). Ingress players, in their creation and constant interaction with portals, assist in the mapping of material environments—benefiting both communities of play and the game’s designers, Niantic Labs and parent company Google. Players are able to submit portals to the game’s developers if their proposed portal meets the satisfaction of the developer’s portal requirements. Portals may be erected at “a location with a cool story, a place in history or educational value … a cool piece of art or unique architecture … a hidden gem of hyper-local spot” (Google, Candidate Portal criteria). A large number of public marks form the basis of Ingress portals, alongside plaques and prominent signage. Significantly, through their submission of portals players are participating in legitimising the history of a number of locations, ensuring up-to-date mapping of locations and landmarks. While a number of other landmarks form the basis of Ingress’s dense map of material environments, this paper is primarily concerned with the role public art plays in the practice of urban play and the curatorial possibilities of urban play. Given the portal criteria put in place by the game’s developers, Ingress pays a certain amount of attention to the historical, sociocultural, and material circumstance which constitute specific locations. As a mobile game, Ingress occupies a certain place within the history of playing in urban environments. Such historical practices have been previously discussed at length, drawing comparisons between practices of urban mobility which are themselves situated in specific historical and sociocultural movements (de Souza e Silva and Hjorth; Flanagan; Stevens). Ingress, via its inclusion of street art as a potential anchor for digital portals, draws on this historical struggle over urban environments and the inherent questions of functionality and organisation which emerge from this struggle. For Stenros, Montola, and Mäyrä (262), pervasive gaming, a form of urban mobile gaming, occupies a similar cultural space to that of street art or graffiti. They argue that both practices are located within a larger struggle over public space—a struggle grounded in urbanisation, legislation, and cultural norms. Drawing comparisons between more contemporary forms of urban mobility, such as the practice/sport of parkour or skateboarding, and the historically situated flâneur or urban stroller, the authors suggest that pervasive forms of gaming and play occupy a similar liminal space and are grounded in questions of urban functionality. Similarly, the urban space may become a gallery or canvas, a space that may be subject to curatorship that is not bound to institutional bodies. The organisation and experience of urban environments then becomes deeply involved in a contested ownership and questions of functionality that are at the heart of urban play.Within the context of Australia, the struggle over the legitimacy of both street art and video games has been subject to ongoing legal discourses. The liminal relationship between gaming and street art is perhaps best illustrated by the 2006 game Marc Ecko’s Getting Up: Contents Under Pressure. The game was granted an MA15+ rating under the existing model of video game regulation but was later refused classification due to its depiction of antisocial behaviour. The game’s rating was appealed by the Queensland Local Government Association. Apperley (“Video”) provides further details on this issue, situating the legislative decision within the historical and political context of Australia at the time, and offering insight into the means in which Getting Up represented street art as a legitimate art form. The game’s narrative, a dystopian future where graffiti is mobilised as a form of social protest against authoritarian bodies, is similar to that of the 2002 game Jet Set Radio Future. However, unlike Jet Set, Getting Up was grounded in a detailed representation of graffiti subcultures. Getting Up’s refused classification is symbolic of the later Australian landscape in which video games and street art occupy a liminal space between art form and artistic practice. The key issue, that of antisocial behaviour, links to the notion of cultural norms and the functionality, organisation, and representations within urban spaces and, moreover, within spaces of play. This struggle for legitimacy is key to understanding the relationship between street art and urban play. Despite the struggle to overcome the functionality of urban environments, street art retains levels of value as a form of cultural heritage. Both Merrill and MacDowall discuss the cultural functions of graffiti and street art, focusing on what Merrill terms a turn towards “post-graffiti”—a shift from the historical and cultural roots of street art and the practice of tagging (373). Such a turn is exemplified by an increased public interest: a legitimisation of artistic practices. Perhaps the most notable figure of such a shift is the Bristol artist Banksy, who is most famous for stencil based art. Graffiti and street art have arguably moved beyond their function as a subversive and subcultural movement, occupying a more legitimate space within urban environments and general public discourse. Within the context of Ingress, street art holds the potential to exist as a digital node of equal value to historical plaques, public libraries, or large commissioned public artworks. This shift, argues Merrill (385) allows for street art and graffiti to be viewed as a form of alternative heritage to urban environments and cultural movements within specific locations. For MacDowell (476), graffiti may be viewed as a form of folk art, subject to new-found romanticism within the context of this “post-graffiti” turn. That is, as a form of alternative heritage, graffiti and street art signify historically situated sociocultural movements and the roots of the practice itself. Games such as Ingress, then, not only legitimate street art as a form of cultural heritage via their inclusion in a non-hierarchical network alongside longstanding institutionalised buildings and artworks but also allow players to participate in an archiving of street art through interactive cartography. The practice of playing Ingress, then, is not only a means of viewing and exploring existing street art but also a direct process in achieving and curating historically situated works of art. Fig. 2: Portal information illustrating possible actions, portal level, and resonator information. Urban Play and “the New Curatorship”Having considered the role of graffiti or street art within urban play as a form of cultural heritage, as a means of linking to the roots of the practice itself and signifying a struggle over the urban environment as a space of predetermined functions, the question then is: what role does the practice of curatorship have within this mesh of interconnected practices? For Bennett and Beudel, the work of the curator, as a caretaker of cultural heritage, is often institutionalised. Within the context of the city, such institutionalisation is itself a symptom of the city as a spectacle. The authors argue that there is the potential for art to be present on a range of surfaces within the urban environment, and call into question the role of the curator within this process.As Groys notes, since Duchamp, the ontological division between the labour of making art and displaying art has collapsed. Public urban spaces, as designed spaces regulated by institutional bodies, are subject to the changing practice of audiences. That is, those who inhabit and experience the urban environment itself now have the possibility to participate or subvert traditional curatorial structures. Drawing on the etymology of the word “curate” as related to “cure,” Groys (53) suggests that the exhibition practice is thus a cure to the powerlessness of the image—a contextualisation of the image within new institutionalised frameworks for a viewing public. Who, then, in the network of relations that is urban play, constitutes this public? Ingress players function as one faction of a public who view, inhabit, move through, and experience the urban environment and any subsequent street art within. As such, they have the potential to take on a curatorial role within the organisation of street art—recontextualising such artworks and generating a new shared understanding of the sociocultural and material conditions which contribute to a broad understanding of the urban and urban play. As such, these forms of digitally mediated urban play blur boundaries between production, consumption, and play. Players, regardless of whether they had a hand in submitting portals to the game’s developers, are articulating a collectively organised database of public art. The practice of curation, as described by Potter, is essential for contemporary digital gaming practices. Players are constantly participating in transmedia landscapes, articulating their literacies through the practice of arranging, assembling, cataloguing, collecting, distributing, and disassembling digital media (Apperley “Glitch” 240; Potter 175). Within Apperley’s example of Minecraft, play unites creativity and the curatorial as one activity. Within the context of Ingress, the practice of play brings together the practice of cartography and of the curatorial. Players, as individuals and as larger localised or global factions, participate in a global mapping of material space, expanding Google’s already extensive collection of cartographic data. Players are more concerned with exploring and territorialising within the context of local spaces, at the level of the national or regional. Such practices are an articulation of localised bodies of knowledge and often of local histories and contexts. Street art forms an integral part of this sociocultural and material fabric which underscores the practice of play. Thus, urban spaces are not subject to a transformative process, but rather to a collective curatorship whereby street art, and its embedded cultural heritage, form a key foundation of how play is performed within urban environments. Through the practice of arranging, assembling, cataloguing, collecting, distributing, and disassembling, the practices of urban play may be thought of as what Potter terms “new curatorship.” Potter’s notion of curatorship is grounded in the identity formation of young children through their use of social media and articulation of digital literacy practices. With playful urban practices such as Ingress, this practice is an articulation of urban literacies: of understanding the rich cultural heritage of specific locations, and of constituting the player’s identity as tied to these specific locations. Players no longer perform merely as an audience for existing forms of urban or street art. Alongside the technological infrastructures put in place by the game’s developers, Niantic Labs and Google, players may be viewed as actively participating in a curatorial process. Players, in their articulation of complex systems and archives of street art, through the ability to constantly update, document, and construct urban narratives with street art at their core, may be viewed as co-curating urban environments. Working together with developers, street artists, and urban planners, players are constantly re-developing and sharing a new shared understanding of urban environments and the complex network of relations which constitutes the urban environment and the practice of urban play.Fig. 3: Players may vote on and contribute new photographs to maintain accurate records of art.Conclusion To play Ingress is to participate in a situated practice of play. Here, play is grounded in material and sociocultural circumstance, with street art and graffiti representing just one of many practices which inform contemporary urban play. Within the context of Ingress, street art is played with as an object within the game (a portal), but it also occupies a similar liminal space. Both urban games and street art have been subject to ongoing debates about the functionality of urban spaces and appropriate behaviour within these spaces. Ingress also taps into street art as a form of cultural heritage; it represents shifts in power dynamics, local histories, and a range of other significant local histories. To play with street art is to acknowledge its roots, both on an international and local level. With the ability to digitally archive these histories and locations, as well as engage in the cartographic practice of urban play, Ingress players can thus be thought of as curators of the city. Through the lens of new curatorship, urban play can be thought of as a form of re-reading of urban environments, as a process of exhibiting a new-found shared understanding of specific locations and public artworks. Street art and graffiti are just one of many sociocultural and material circumstances which inform the practice of urban play. During play, there is a critical reflection on the role street art has, not only during the current context of play but also more broadly as a key component of contemporary urban landscapes. Street art functions as a form of cultural heritage, as an element of urban exploration, and as a point of reference for navigating city spaces. Ingress brings together these interrelated forms of organising and sharing experiences of urban environments, through the practice of curation. Such practices are reflexively intertwined with playing urban mobile games as such Ingress. As such, the act of playing Ingress is, in essence, a form of urban literacy, as a practice of understanding the rich and complex sociocultural conditions which contribute to our understanding of urban environments. It is a practice of collecting, assembling, and exhibiting a range of locations. The practice of playing Ingress is a collective curation of city spaces on a global scale.References Apperley, Thomas. “Glitch Sorting: Minecraft, Curation, and the Post Digital.” Postdigital Aesthetics: Art, Computation and Design. Ed. David M. Berry and Michael Dieter. London: Palgrave Macmillan, 2015. 232–44.———. “Video Games in Australia.” The Video Game Explosion: A History from PONG to Playstation and Beyond. Ed. Mark J.P. Wolf. USA: Greenwood P, 2008. 22–29.———. Gaming Rhythms: Play and Counterplay from the Situated to the Global. Amsterdam: Institute of Network Cultures, 2009.Bennett, Jill, and Saskia Beudel. Curating Sydney: Imagining the City’s Future. Sydney: UNSW P, 2014.De Souza e Silva, Adriana, and Larissa Hjorth. “Playful Urban Spaces: A Historical Approach to Mobile Games.” Simulation & Gaming 40.5 (2009): 602–25. Dourish, Paul. “What We Talk about When We Talk about Context.” Personal Ubiquitous Computing 8.1 (2004): 19–30.Flanagan, Mary. Critical Play: Radical Game Design. Cambridge, MA: MIT P, 2009.———. “Locating Play and Politics: Real World Games & Activism.” Leonardo Electronic Almanac 16.2–3 (2008). 5 June 2015 ‹http://www.leonardo.info/LEA/perthDAC/MFlanagan_LEA160203.pdf›.Groys, Boris. Going Public. Ed. Julieta Aranda, Brian Kuan Wood, and Anton Vidokle. Berlin: Sternberg Press, 2010.Google. “Candidate Portal Criteria.” 2015. 5 June 2015 ‹https://support.google.com/ingress/answer/3066197?hl=en›. ———. “New Portal Submissions.” 2015. 5 June 2015 ‹https://support.google.com/ingress/answer/2808254?hl=en›. Lave, Jean, and Etienne Wenger. Situated Learning: Legitimate Peripheral Participation. Cambridge: Cambridge UP, 1991.MacDowall, Lachlan. “In Praise of 70K: Cultural Heritage and Graffiti Style.” Continuum 20.4 (2006): 471–84.Merrill, Samuel. “Keeping It Real? Subcultural Graffiti, Street Art, Heritage and Authenticity.” International Journal of Heritage Studies 21.4 (2015): 369–89.Niantic Labs. Ingress. Android Mobile Application. 2012.Potter, John. Digital Media and Learner Identity: The New Curatorship. New York: Palgrave Macmillan, 2012.Stenros, Jaakko, Markus Montola, and Frans Mäyrä. “Pervasive Games in Media Culture.” Pervasive Games: Theory and Design. Eds. Markus Montola, Jakko Stenros, and Annika Waern. Amsterdam: CRC P, 2009.Stevens, Quentin. The Ludic City: Exploring the Potential of Public Spaces. New York: Routledge, 2007.Suchman, Lucy. Human-Machine Reconfigurations: Plans and Situated Actions. 2nd ed. Cambridge: Cambridge UP, 2006.———. Plans and Situated Actions: The Problem of Human-Machine Communication. Cambridge: Cambridge UP, 1987.Yates, Simeon J., and Karen Littleton. “Understanding Computer Game Cultures: A Situated Approach.” Information, Communication & Society 2.4 (1999): 566–83.

As I round the corner from Church Street onto Vesey, I am abruptly met with the façade of St. Paul’s Chapel and by the sudden memory of two things, both of which have not yet happened. I think about how, in a couple of decades, the area surrounding me will be burnt to the ground. I also recall how, just after the turn of the twenty-first century, the area will again crumble onto itself. It is 1759, and I—via my avatar—am wandering through downtown New York City in the videogame space of Assassin’s Creed: Rogue (AC:R). These spatial and temporal memories stem from the fact that I have previously (that is, earlier in my life) played an AC game set in New York City during the War for Independence (later in history), wherein the city’s lower west side burns at the hands of the British. Years before that (in my biographical timeline, though much later in history) I watched from twenty-something blocks north of here as flames erupted from the twin towers of the World Trade Center. Complicating the situation further, Michel de Certeau strolls with me in spirit, pondering observations he will make from almost this exact location (though roughly 1,100 feet higher up) 220 years from now, around the time I am being born. Perhaps the oddest aspect of this convoluted and temporally layered experience is the fact that I am not actually at the corner of Church and Vesey in 1759 at all, but rather on a couch, in Virginia, now. This particular type of sudden arrival at a space is only possible when it is not planned. Prior to the moment described above, I had finished a “mission” in the game that involved my coming to the city, so I decided I would just walk around a bit in the newly discovered digital New York of 1759. I wanted to take it in. I wanted to wander. Truly Being-in-a-place means attending to the interconnected Being-ness and Being-with-ness of all of the things that make up that place (Heidegger; Haraway). Conversely, to travel to or through a place entails a type of focused directionality toward a place that you are not currently Being in. Wandering, however, demands eschewing both, neither driven by an incessant goal, nor stuck in place by introspective ruminations. Instead, wandering is perhaps best described as a sort of mobile openness. A wanderer is not quite Benjamin’s flâneur, characterised by an “idle yet assertive negotiation of the street” (Coates 28), but also, I would argue, not quite de Certeau’s “Wandersmünner, whose bodies follow the thicks and thins of an urban ‘text’ they write without being able to read it” (de Certeau 93). Wandering requires a concerted effort at non-intentionality. That description may seem to fold in on itself, to be sure, but as the spaces around us are increasingly “canalized” (Rabinow and Foucault) and designed with specific trajectories and narratives in mind, inaction leads to the unconscious enacting of an externally derived intention; whereas any attempt to subvert that design is itself a wholly intentional act. This is why wandering is so difficult. It requires shedding layers. It takes practice, like meditation.In what follows, I will explore the possibility of revelatory moments enabled by the shedding of these layers of intention through my own experience in digital space (maybe the most designed and canalized spaces we inhabit). I come to recognise, as I disavow the designed narrative of game space, that it takes on other meanings, becomes another space. I find myself Being-there in a way that transcends the digital as we understand it, experiencing space that reaches into the past and future, into memory and fiction. Indeed, wandering is liminal, betwixt fixed points, spaces, and times, and the text you are reading will wander in this fashion—between the digital and the physical, between memory and experience, and among multiple pasts and the present—to arrive at a multilayered subjective sense of space, a palimpsest of placemaking.Before charging fully into digital time travel, however, we must attend to the business of context. In this case, this means addressing why I am talking about videogame space in Certaudian terms. Beginning as early as 1995, videogame theorists have employed de Certeau’s notion of “spatial stories” in their assertions that games allow players to construct the game’s narrative by travelling through and “colonizing” the space (Fuller and Jenkins). Most of the scholarship involving de Certeau and videogames, however, has been relegated to the concepts of “map/tour” in looking at digital embodiment within game space as experiential representatives of the place/space binary. Maps verbalise spatial experience in place terms, such as “it’s at the corner of this and that street”, whereas tours express the same in terms of movement through space, as in “turn right at the red house”. Videogames complicate this because “mapping is combined with touring when moving through the game-space” (Lammes).In Games as Inhabited Spaces, Bernadette Flynn moves beyond the map/tour dichotomy to argue that spatial theories can approach videogaming in a way no other viewpoint can, because neither narrative nor mechanics of play can speak to the “space” of a game. Thus, Flynn’s work is “focused on completely reconceiving gameplay as fundamentally configured with spatial practice” (59) through de Certeau’s concepts of “strategic” and “tactical” spatial use. Flynn explains:The ability to forge personal directions from a closed simulation links to de Certeau’s notion of tactics, where users can create their own trajectories from the formal organizations of space. For de Certeau, tactics are related to how people individualise trajectories of movement to create meaning and transformations of space. Strategies on the other hand, are more akin to the game designer’s particular matrix of formal structures, arrangements of time and space which operate to control and constrain gameplay. (59)Flynn takes much of her reading of de Certeau from Lev Manovich, who argues that a game designer “uses strategies to impose a particular matrix of space, time, experience, and meaning on his viewers; they, in turn, use ‘tactics’ to create their own trajectories […] within this matrix” (267). Manovich believes de Certeau’s theories offer a salient model for thinking about “the ways in which computer users navigate through computer spaces they did not design” (267). In Flynn’s and Manovich’s estimation, simply moving through digital space is a tactic, a subversion of its strategic and linear design.The views of game space as tactical have historically (and paradoxically) treated the subject of videogames from a strategic perspective, as a configurable space to be “navigated through”, as a way of attaining a certain goal. Dan Golding takes up this problem, distancing our engagement from the design and calling for a de Certeaudian treatment of videogame space “from below”, where “the spatial diegesis of the videogame is affordance based and constituted by the skills of the player”, including those accrued outside the game space (Golding 118). Similarly, Darshana Jayemanne adds a temporal element with the idea that these spatial constructions are happening alongside a “complexity” and “proliferation of temporal schemes” (Jayemanne 1, 4; see also Nikolchina). Building from Golding and Jayemanne, I illustrate here a space wherein the player, not the game, is at the fulcrum of both spatial and temporal complexity, by adding the notion that—along with skill and experience—players bring space and time with them into the game.Viewed with the above understanding of strategies, tactics, skill, and temporality, the act of wandering in a videogame seems inherently subversive: on one hand, by undergoing a destination-less exploration of game space, I am rejecting the game’s spatial narrative trajectory; on the other, I am eschewing both skill accrual and temporal insistence to attempt a sense of pure Being-in-the-game. Such rebellious freedom, however, is part of the design of this particular game space. AC:R is a “sand box” game, which means it involves a large environment that can be traversed in a non-linear fashion, allowing, supposedly, for more freedom and exploration. Indeed, much of the gameplay involves slowly making more space available for investigation in an outward—rather than unidirectional—course. A player opens up these new spaces by “synchronising a viewpoint”, which can only be done by climbing to the top of specific landmarks. One of the fundamental elements of the AC franchise is an acrobatic, free-running, parkour style of engagement with a player’s surroundings, “where practitioners weave through urban environments, hopping over barricades, debris, and other obstacles” (Laviolette 242), climbing walls and traversing rooftops in a way unthinkable (and probably illegal) in our everyday lives. People scaling buildings in major metropolitan areas outside of videogame space tend to get arrested, if they survive the climb. Possibly, these renegade climbers are seeking what de Certeau describes as the “voluptuous pleasure […] of ‘seeing the whole,’ of looking down on, totalizing the most immoderate of human texts” (92)—what he experienced, looking down from the top of the World Trade Center in the late 1970s.***On digital ground level, back in 1759, I look up to the top of St. Paul’s bell tower and crave that pleasure, so I climb. As I make my way up, Non-Player Characters (NPCs)—the townspeople and trader avatars who make up the interactive human scenery of the game—shout things such as “You’ll hurt yourself” and “I say! What on earth is he doing?” This is the game’s way of convincing me that I am enacting agency and writing my own spatial story. I seem to be deploying “tricky and stubborn procedures that elude discipline without being outside the field in which it is exercised” (de Certeau 96), when I am actually following the program the way I am supposed to. If I were not meant to climb the tower, I simply would not be able to. The fact that game developers go to the extent of recording dialogue to shout at me when I do this proves that they expect my transgression. This is part of the game’s “semi-social system”: a collection of in-game social norms that—to an extent—reflect the cultural understandings of outside non-digital society (Atkinson and Willis). These norms are enforced through social pressures and expectations in the game such that “these relative imperatives and influences, appearing to present players with ‘unlimited’ choices, [frame] them within the parameters of synthetic worlds whose social structure and assumptions are distinctly skewed in particular ways” (408). By using these semi-social systems, games communicate to players that performing a particular act is seen as wrong or scandalous by the in-game society (and therefore subversive), even when the action is necessary for the continuation of the spatial story.When I reach the top of the bell tower, I am able to “synchronise the viewpoint”—that is, unlock the map of this area of the city. Previously, I did not have access to an overhead view of the area, but now that I have indulged in de Certeau’s pleasure of “seeing the whole”, I can see not only the tactical view from the street, but also the strategic bird’s-eye view from above. From the top, looking out over the city—now The City, a conceivable whole rather than a collection of streets—it is difficult to picture the neighbourhood engulfed in flames. The stair-step Dutch-inspired rooflines still recall the very recent change from New Amsterdam to New York, but in thirty years’ time, they will all be torched and rebuilt, replaced with colonial Tudor boxes. I imagine myself as an eighteenth-century de Certeau, surveying pre-ruination New York City. I wonder how his thoughts would have changed if his viewpoint were coloured with knowledge of the future. Standing atop the very symbol of global power and wealth—a duo-lith that would exist for less than three decades—would his pleasure have been less “voluptuous”? While de Certeau considers the viewer from above like Icarus, whose “elevation transfigures him into a voyeur” (92), I identify more with Daedalus, preoccupied with impending disaster. I swan-dive from the tower into a hay cart, returning to the bustle of the street below.As I wander amongst the people of digital 1759 New York, the game continuously makes phatic advances at me. I bump into others on the street and they drop boxes they are carrying, or stumble to the side. Partial overheard conversations going on between townspeople—“… what with all these new taxes …”, “… but we’ve got a fine regiment here …”—both underscore the historical context of the game and imply that this is a world that exists even when I am not there. These characters and their conversations are as much a part of the strategic makeup of the city as the buildings are. They are the text, not the writers nor the readers. I am the only writer of this text, but I am merely transcribing a pre-programmed narrative. So, I am not an author, but rather a stenographer. For this short moment, though, I am allowed by the game to believe that I am making the choice not to transcribe; there are missions to complete, and I am ignoring them. I am taking in the city, forgetting—just as the design intends—that I am the only one here, the only person in the entire world, indeed, the person for whom this world exists.While wandering, I also experience conflicts and mergers between what Maurice Halbwachs has called historical, autobiographical, and collective memory types: respectively, these are memories created according to historical record, through one’s own life experience, and by the way a society tends to culturally frame and recall “important” events. De Certeau describes a memorable place as a “palimpsest, [where] subjectivity is already linked to the absence that structures it as existence” (109). Wandering through AC:R’s virtual representation of 1759 downtown New York, I am experiencing this palimpsest in multiple layers, activating my Halbwachsian memories and influencing one another in the creation of my subjectivity. This is the “absence” de Certeau speaks of. My visions of Revolutionary New York ablaze tug at me from beneath a veneer of peaceful Dutch architecture: two warring historical memory constructs. Simultaneously, this old world is painted on top of my autobiographical memories as a New Yorker for thirteen years, loudly ordering corned beef with Russian dressing at the deli that will be on this corner. Somewhere sandwiched between these layers hides a portrait of September 11th, 2001, painted either by collective memory or autobiographical memory, or, more likely, a collage of both. A plane entering a building. Fire. Seen by my eyes, and then re-seen countless times through the same televised imagery that the rest of the world outside our small downtown village saw it. Which images are from media, and which from memory?Above, as if presiding over the scene, Michel de Certeau hangs in the air at the collision site, suspended a 1000 feet above the North Pool of the 9/11 Memorial, rapt in “voluptuous pleasure”. And below, amid the colonists in their tricorns and waistcoats, people in grey ash-covered suits—ambulatory statues; golems—slowly and silently march ever uptown-wards. Dutch and Tudor town homes stretch skyward and transform into art-deco and glass monoliths. These multiform strata, like so many superimposed transparent maps, ground me in the idea of New York, creating the “fragmentary and inward-turning histories” (de Certeau 108) that give place to my subjectivity, allowing me to Be-there—even though, technically, I am not.My conscious decision to ignore the game’s narrative and wander has made this moment possible. While I understand that this is entirely part of the intended gameplay, I also know that the design cannot possibly account for the particular way in which I experience the space. And this is the fundamental point I am asserting here: that—along with the strategies and temporal complexities of the design and the tactics and skills of those on the ground—we bring into digital space our own temporal and experiential constructions that allow us to Be-in-the-game in ways not anticipated by its strategic design. Non-digital virtuality—in the tangled forms of autobiographical, historic, and collective memory—reaches into digital space, transforming the experience. Further, this changed game-experience becomes a part of my autobiographical “prosthetic memory” that I carry with me (Landsberg). When I visit New York in the future, and I inevitably find myself abruptly met with the façade of St Paul’s Chapel as I round the corner of Church Street and Vesey, I will be brought back to this moment. Will I continue to wander, or will I—if just for a second—entertain the urge to climb?***After the recent near destruction by fire of Notre-Dame, a different game in the AC franchise was offered as a free download, because it is set in revolutionary Paris and includes a very detailed and interactive version of the cathedral. Perhaps right now, on sundry couches in various geographical locations, people are wandering there: strolling along the Siene, re-experiencing time they once spent there; overhearing tense conversations about regime change along the Champs-Élysées that sound disturbingly familiar; or scaling the bell tower of the Notre-Dame Cathedral itself—site of revolution, desecration, destruction, and future rebuilding—to reach the pleasure of seeing the strategic whole at the top. And maybe, while they are up there, they will glance south-southwest to the 15th arrondissement, where de Certeau lies, enjoying some voluptuous Icarian viewpoint as-yet unimagined.ReferencesAtkinson, Rowland, and Paul Willis. “Transparent Cities: Re‐Shaping the Urban Experience through Interactive Video Game Simulation.” City 13.4 (2009): 403–417. DOI: 10.1080/13604810903298458.Benjamin, Walter. The Arcades Project. Trans. Howard Eiland and Kevin McLaughlin. Ed. Rolf Tiedmann. Cambridge, Mass.: Belknap Press, 2002. Coates, Jamie. “Key Figure of Mobility: The Flâneur.” Social Anthropology 25.1 (2017): 28–41. DOI: 10.1111/1469-8676.12381.De Certeau, Michel. The Practice of Everyday Life. Translated by Steven Rendall. Berkeley: University of California Press, 1984.Flynn, Bernadette. “Games as Inhabited Spaces.” Media International Australia, Incorporating Culture and Policy 110 (2004): 52–61. DOI: 10.1177/1329878X0411000108.Fuller, Mary, and Henry Jenkins. “‘Nintendo and New World Travel Writing: A Dialogue’ [in] CyberSociety: Computer-Mediated Communication and Community.” CyberSociety: Computer-Mediated Communication and Community. Ed. Steve Jones. Thousand Oaks: Sage, 1994. 57–72. <https://contentstore.cla.co.uk/secure/link?id=7dc700b8-cb87-e611-80c6-005056af4099>.Golding, Daniel. “Putting the Player Back in Their Place: Spatial Analysis from Below.” Journal of Gaming & Virtual Worlds 5.2 (2013): 117–30. DOI: 10.1386/jgvw.5.2.117_1.Halbwachs, Maurice. The Collective Memory. New York: Harper & Row, 1980.Haraway, Donna. Staying with the Trouble: Making Kin in the Chthulucene. Durham: Duke University Press Books, 2016.Heidegger, Martin. Existence and Being. Chicago: Henry Regnery Company, 1949.Jayemanne, Darshana. “Chronotypology: A Comparative Method for Analyzing Game Time.” Games and Culture (2019): 1–16. DOI: 10.1177/1555412019845593.Lammes, Sybille. “Playing the World: Computer Games, Cartography and Spatial Stories.” Aether: The Journal of Media Geography 3 (2008): 84–96. DOI: 10.1080/10402659908426297.Landsberg, Alison. Prosthetic Memory: The Transformation of American Remembrance in the Age of Mass Culture. New York: Columbia University Press, 2004.Laviolette, Patrick. “The Neo-Flâneur amongst Irresistible Decay.” Playgrounds and Battlefields: Critical Perspectives of Social Engagement. Eds. Martínez Jüristo and Klemen Slabina. Tallinn: Tallinn University Press, 2014. 243–71.Manovich, Lev. The Language of New Media. Cambridge, Massachusetts: MIT Press, 2002.Nikolchina, Miglena. “Time in Video Games: Repetitions of the New.” Differences 28.3 (2017): 19–43. DOI: 10.1215/10407391-4260519.Rabinow, Paul, and Michel Foucault. “Interview with Michel Foucault on Space, Knowledge and Power.” Skyline (March 1982): 17–20.