The shift from classic 2D maps to 3D makes some analysis and phenomenons explicits : slope, exposition, some hydrologic phenomenons becomes directly viewable... As an example, a scalar or vectorial field (geology, atmosphere, etc ..) is difficult to present in 2D. Using 3D, it's possible to shift from the classic 'cutting plane' to the 'cutting box'. The use of Virtual Reality expends this and leads to new representations, and new tools for the exploration of geographic data..
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As an example of this concept, you'll find below what intervisibility analysis may be using 3D ...
First, what's available in 2D (or is it 2.5 D ?) : point to point intervisibility analysis using MapInfo tm and Vertical Mapper tm.
An altimetric model (shaded), is used to compute the regions viewable by an observer.. Clutters are hard to find, their strength are unknown, the viewing angle isn't reported. It's very hard to derive from this simple map what the intervisibility is if the user or a sought object is free to change it's altitude. |
An alternative representation in 3D:
Intervisibility analysis between a point and a path (for example, the path can be the path of the user, moving freely in the scene, or a GPS gathered data, or a path define in a GIS for mission planning). The surface is drawn in real time.
Another exemple of explicit intervisibility between N moving points :