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The Secret of Viewshed Analysis: How to See Invisible Corners on a Big Map?
With the advancement of technology, viewshed analysis has become an important tool in geographic information systems (GIS), helping experts find visibility areas in complex terrain. This technology uses a digital elevation model (DEM) to calculate the visible range of a specific location, allowing us to have a deeper understanding of the surrounding environment, especially showing its importance in urban planning and environmental management.
Basic process of viewshed analysis
Viewshed analysis is a computational algorithm used to delineate the area that can be seen from a specific location. The technology helps engineers and planners choose the best locations for construction, such as communications towers or road designs. When performing viewshed analysis, all pixels from the observation point to the target point will be checked to determine whether there is occlusion based on the elevation value.
Viewshed analysis can be calculated from a single point or multiple points as needed, using different variables to adjust the results.
Users can easily perform analysis through various GIS programs, such as ArcGIS Pro, QGIS, and GRASS GIS. During this process, the algorithm considers elevation differences and determines visibility by checking line-of-sight connectivity. If there are other areas with higher elevations blocking the line of sight, the area will not be included in the field of view; conversely, if there is no obstruction, the area will be visible.
Application of viewshed analysis
In addition to siting communications towers, viewshed analysis can be applied to a variety of situations. For example, as a building is added, viewshed analysis can assess the visual impact of that building, revealing which surrounding areas will be obscured or visible. In addition, in the setting of fire observation stations, viewshed analysis helps to place observation points in optimal locations to effectively monitor large areas of forest.
Viewshed analysis can also be used to determine the visibility of historic routes, helping people better understand the landscape as seen by famous pioneers of the West.
For example, the Wyoming Bureau of Land Management conducted a viewshed analysis to determine the visibility of historic trails. Not only are five different visible areas identified, but the changes in each area at different heights and lines of sight are also shown. In these analyses, data show the terrain visible to pioneers in the West as they traveled.
Unique sightshed analysis case
The United States Geological Survey (USGS) also uses viewshed analysis to support NASA's Mars exploration mission. When NASA needs to select an appropriate landing site for a Mars rover, the USGS is responsible for developing maps of the best locations. In this analysis, the viewshed shows the visible area between different landing sites, helping to design more favorable detection scenarios.
This is not only an application on Earth, the concept of horizon analysis also extends to the scope of planetary exploration, demonstrating its rich potential in different fields.
In summary, viewshed analysis is a powerful tool with applications ranging from urban planning to environmental management and even space exploration. As technology advances, more innovative applications may appear in the future, challenging our imagination. As we begin to learn more about these technologies, we may wonder: What unexplored corners are there waiting for us to uncover?
