A Procedural Construction Method for Interactive Map Symbols Used for Disasters and Emergency Response

The timely and accurate mapping of dynamic disasters and emergencies is an important task that is necessary for supporting the decision-making that can improve the efficiency of rescue and response efforts. The existing emergency symbol libraries are primarily composed of point symbols and simple line symbols, focusing on the representation of disasters, related facilities, and operations. However, various existing response factors (e.g., the distribution and types of emergency forces) are also important for further decision-making and emergency responses; there is a need to design complex and diverse symbols to represent this rich information. Moreover, traditional mapping systems only provide static map symbols that cannot be easily edited after creation, making it difficult to support interactive editing after the symbols are mapped, thus hindering the representation of dynamic disasters and response factors. This article targets a solution of the above issues by proposing a procedural construction method of interactive map symbols for dynamic disasters and emergency responses. There are two primary research points. First, an emergency response and decision symbol library was classified and integrated into the existing attachments to form a richer symbol library for comprehensively representing disasters and emergencies. Second, an interactive map symbol procedural construction method was designed based on (1) primitive geometric compositions and geometric graphics algorithms to construct the map symbol graphics; (2) an interactive graphics control and drawing attributes configuration method to support user interactive editing of the visual variables of the mapped symbols; (3) and a dynamic updating and drawing strategy to support the real-time refreshing of the changing visual variables. The experiment was conducted using the Wenchuan earthquake as a case study, and the results demonstrate a powerful capacity of the produced interactive map symbols, which will contribute to the improvement of the mapping efficiency and representation capability of disasters and emergency response

A web-based strategy to reuse grids in geographic modeling

Grids are essential for the production of geospatial data and environmental modeling. Over many years of research, numerous grids have been designed and developed. Reusing grids can reduce usage costs. However, there are still factors that impede grid reusability. Gridding algorithms are difficult to share and reuse on another device because most gridding algorithms have certain requirements for the devices’ operating system (Windows or Linux) and runtime environment (Python, C++, or C#). Additionally, grid data are organized into various formats by the gridding algorithms, and parsing schemes need to be customized prior to using the data based on the rules governing the data organization. However, data customization tasks are difficult to replicate. This article presents a web-based grids reusability strategy to mitigate the problems encountered when reusing gridding algorithms and grid data. To reuse gridding algorithms, a service-oriented gridding algorithm encapsulation method is studied. Based on this encapsulation method, heterogeneous gridding algorithm programs can be invoked as standard web services regardless of a device’s operating environment. Moreover, a grid data wrapping method is also studied in this strategy to assists algorithm users with parsing grid data in a unified manner and more easily access grid data on the web. Finally, a web-based prototype system is established to demonstrate the strategy’s effectiveness and viability reusability

A model-service deployment strategy for collaboratively sharing geo-analysis models in an open web environment

Geo-analysis models can be shared and reused via model-services to support more effective responses to risks and help to build a sustainable world. The deployment of model-services typically requires significant effort, primarily because of the complexity and disciplinary specifics of geo-analysis models. Various modelling participants engage in the collaborative modelling process: geo-analysis model resources are provided by model providers, computational resources are provided by computational resource providers, and the published model-services are accessed by model users. This paper primarily focuses on model-service deployment, with the basic goal of providing a collaboration-oriented method for modelling participants to conveniently work together and make full use of modelling and computational resources across an open web environment. For model resource providers, a model-deployment description method is studied to help build model-deployment packages; for computational resource providers, a computational resource description method is studied to help build model-service containers and connectors. An experimental system for sharing and reusing geo-analysis models is built to verify the capability and feasibility of the proposed methods. Through this strategy, modellers from dispersed regions can work together more easily, thus providing dynamic and reliable geospatial information for Future Earth studies

A Representation Method for Complex Road Networks in Virtual Geographic Environments

Road networks are important for modelling the urban geographic environment. It is necessary to determine the spatial relationships of road intersections when using maps to help researchers conduct virtual urban geographic experiments (because a road intersection might occur as a connected cross or as an unconnected bridge overpass). Based on the concept of using different map layers to organize the render order of each road segment, three methods (manual, semi-automatic and mask-based automatic) are available to help map designers arrange the rendering order. However, significant efforts are still needed, and rendering efficiency remains problematic with these methods. This paper considers the Discrete, Crossing, Overpass, Underpass, Conjunction, Up-overlap and Down-overlap spatial relationships of road intersections. An automatic method is proposed to represent these spatial relationships when drawing road networks on a map. The data-layer organization method (reflecting road grade and elevation-level information) and the symbol-layer decomposition method (reflecting road covering order in the vertical direction) are designed to determine the rendering order of each road element when rendering a map. In addition, an “auxiliary-drawing-action” (for drawing road segments belonging to different grades and elevations) is proposed to adjust the rendering sequences automatically. Two experiments are conducted to demonstrate the feasibility and efficiency of the method, and the results demonstrate that it can effectively handle spatial relationships of road networks in map representations. Using the proposed method, the difficulty of rendering complex road networks can be reduced

ReinterpretedTexture_Prototype

This is a web prototype system about a vector point symbol rendering method based on the texture structure. The rendering context is WebGL2, and the base map is presented by Mapbox GL js. A texel in the texture is a piece of vertex information in the size of 4 Bytes. It contains a pair of coordinates and a color index of one of the vertex of a vector point symbol (organized by one triangle strip). GPU Instancing is used to launch the rendering pipeline. All different symbols can be rendered in one draw call by specifying their layout information about where they lie in the texture. With the help of the built-in variable gl_VertexID and textures' random access feature, vertices can be decoded from the symbol texture. By using thie method, both the quality of the vector style and the performance of the raster style can be taken to improve the point symbol drawing on maps.</p

Performance analysis of global HYCOM flow field using Argo profiles

Flow field data generated by ocean models are important for simulating ocean currents and circulation patterns, which are essential components in digital Earth construction. To evaluate the accuracy of model-simulated flow fields, Array for Real-time Geostrophic Oceanography (Argo) float observations can be considered benchmarks. In this study, a novel method for comparing Argo profiles with 3-dimensional trajectories obtained by simulating Argo floats in Hybrid Coordinate Ocean Model (HYCOM)-provided flow fields was proposed. Surface and subsurface trajectories were calculated, and their spatial matching characteristics were analyzed. The results demonstrated that (1) the HYCOM surface and subsurface flow fields generally conform to the basic characteristics and trends of ocean currents; (2) the HYCOM sea surface current field error pattern exhibits a symmetrical distribution centered on the equator in the Northern and Southern Hemispheres and increases with increasing latitude; and (3) the HYCOM subsurface flow field exhibits regional differences, with the largest differences in the Gulf Stream, North Atlantic Warm Current, and Westerly Wind Drift region. Through analysis of the disparities between HYCOM and Argo data, the effectiveness of using model simulation data can be enhanced, and the accuracy and dependability of ocean models can be improved

A loosely integrated data configuration strategy for web-based participatory modeling

Participatory modeling is an important approach for solving complex geo-problems from a comprehensive and holistic viewpoint, and it brings together stakeholders from multiple disciplines to provide diverse resources, including modeling, data fields and computational assets. Data configuration work (e.g., preparing appropriate input data for model execution, connecting a model’s output to the input data of another model) is important for constructing and executing a participatory modeling task. Most current data configuration methods depend on the model integration logic, which presents a challenge when adding new modeling resources into a model to dynamically create and execute new modeling tasks. To support the construction of participatory modeling tasks in a web environment, this article proposes a loosely integrated data configuration strategy for decoupling data configuration work from the execution process of a participatory modeling task. A model service controller is designed for model input/output (I/O) configuration, and a data service controller is designed for data access configuration. These two controllers can help modelers link the data I/O demands of a model-service with the appropriate data-services; thus, different modeling instances can be dynamically joined to a participatory modeling task and executed without reconstructing the original data configuration settings. A prototype participatory modeling system is proposed to demonstrate the flexibility and feasibility of the proposed method using an experimental modeling case. The results show that the proposed data configuration strategy supports the integration of different model-services based on the data dependency relationships and that the complexity and difficulty in configuring data for a participatory modeling tasks in the web environment are minimized

A framework on task configuration and execution for distributed geographical simulation

Geographical simulation is a popular method in geographical and environmental research. Many models developed to address geographic and environmental issues are distributed worldwide. However, due to the lack of portals, these models are still difficult to invoke for geographical simulations in open web environments. This study designs and develops a framework to assemble service-oriented models from volunteers distributed worldwide for geographical simulations on the web. The framework consists of three layers (task layer, data exchange layer, and model execution layer) that establish a network of service-oriented locally shared models and simulation tasks for user configurations. With the help of such a framework, users can configure simulation tasks and invoke suitable models shared worldwide for geographical simulations. This article provides an application of the distributed simulation of gross primary production (GPP) by the Biome-BioGeochemical Cycles (BGC) model in China. This application shows that the framework can be beneficial for model assembly from volunteers' computers and distributed simulation tasks that are run for geographical and environmental issues, which can be applied to Digital Earth initiatives