Scientific and appropriate visualizations increase the effectiveness and readability of disaster information. However, existing fusion visualization methods for disaster scenes have some deficiencies, such as the low efficiency of scene visualization and difficulties with disaster information recognition and sharing. In this paper, a fusion visualization method for disaster information, based on self-explanatory symbols and photorealistic scene cooperation, was proposed. The self-explanatory symbol and photorealistic scene cooperation method, the construction of spatial semantic rules, and fusion visualization with spatial semantic constraints were discussed in detail. Finally, a debris flow disaster was selected for experimental analysis. The experimental results show that the proposed method can effectively realize the fusion visualization of disaster information, effectively express disaster information, maintain high-efficiency visualization, and provide decision-making information support to users involved in the disaster process.

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Emergency risk assessment of debris flows in residential areas is of great significance for disaster prevention and reduction, but the assessment has disadvantages, such as a low numerical simulation efficiency and poor capabilities of risk assessment and geographic knowledge sharing. Thus, this paper focuses on the construction of a VGE (virtual geographic environment) system that provides an efficient tool to support the rapid risk analysis of debris flow disasters. The numerical simulation, risk analysis, and 3D (three-dimensional) dynamic visualization of debris flow disasters were tightly integrated into the VGE system. Key technologies, including quantitative risk assessment, multiscale parallel optimization, and visual representation of disaster information, were discussed in detail. The Qipan gully in Wenchuan County, Sichuan Province, China, was selected as the case area, and a prototype system was developed. According to the multiscale parallel optimization experiments, a suitable scale was chosen for the numerical simulation of debris flow disasters. The computational efficiency of one simulation step was 5 ms (milliseconds), and the rendering efficiency was approximately 40 fps (frames per second). Information about the risk area, risk population, and risk roads under different conditions can be quickly obtained. The experimental results show that our approach can support real-time interactive analyses and can be used to share and publish geographic knowledge.

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Geographic modeling and simulation is now regarded as a fundamental approach to geographic process mining and complex geographic problems, such as dam-break floods. With the rapid development of web services and network technologies in the context of GIS, it is possible to offer a new generation of geographic analysis tools that are based on new types of Web and computer-based geographic environments that are built for understanding geographic processes and problem solving. This paper focuses on the visual analysis and simulation of dam-break flood spatiotemporal process in a network environment. The simulations were implemented with HTML5, WebGL, Ajax and Web Service and other technologies and also included the rapid computation of spatiotemporal process models, B/S network architecture construction, three-dimensional scene rendering optimization and dynamic interaction analysis. Finally, a prototype system was constructed, and an experiment was conducted to analyze dam-break flood spatiotemporal process visually in a case study region in a network simulation. The experimental results show that the scheme addressed in this paper can be used to publish spatiotemporal process information, online impact analyses and three-dimensional visualization representations in a network environment that is suitable for browsing, querying and analysis. This scheme can be used efficiently to understand dam-break flood process and support dam-break risk management.