True non-projected 3D grid world modeling

Question

I did a search on this but I did not find anything much relevant yet. I was wondering how come there is no GIS software that would take a sufficiently accurate 3D surface model of the world (such as based on SRTM's) and put geographic features on it instead of a simplified spheroid.

This would obviate the need for flattening the world using projections, hence remove all distortions, enabling us to make much more accurate measurements. We then wouldn't need to use different projections for different purposes or for different regions of the world.

I'd imagine when we look at the interface of this software, we'd be looking at a curved map, flattened only at the screen. When we zoomed out enough, we could see the entire world as a globe (as an option). The major problem with this approach would be the relatively large size of the 3D surface grid, demanding computation power and a need for developing new libraries for computations.

I think the most of these issues could be solved by getting only the portion of the grid necessary for one's mapping needs.

Answer 1

It is true that data in a global 3D cartesian coordinate system will allow you to do distortion-free calculations of 3D distances and angles. And if users are happy with perspective views of the 3D world then fine. But the advantages stop there.

Much of geographical analysis and civil engineering needs to consider the world as existing in three useful dimensions: a 2D horizontal surface and a 1D vertical direction. Distances and angles are most useful when horizontal. When required, vertical distances exist as elevations. Current GIS data and software cater to such demands via horizontal and vertical coordinates with respect to appropriate horizontal and vertical reference datums.

Answer 2

A high-precision, global 3D Cartesian coordinate system is quite useful to the aerospace industry, where satellites orbit the Earth at large enough distances that understanding the true geometry becomes critical. A high-precision understanding of time is also needed, as some spacecraft orbit upwards of 8km/sec.

For communications with Earth-bound objects on an ocean or on a flat plain, the actual shape of terrain is not as important as the geometry of the Earth Ellipsoid and the spacecraft's orbital path in 3D. Of course terrain does come into play when objects of interest are in a valley or up in the mountains: Terrain can block signals from one satellite, while allowing another. For non-Geostationary spacecraft, as time passes some will appear above the terrain and others will become obscured.

CesiumJS (disclaimer, I'm a contributor) uses a format called Quantized Mesh for streaming 3D terrain to thin web clients. Typically Cesium does not perform these terrain obscuration calculations directly, as this kind of heavy-lifting is better done on the server. So, Quantized Mesh is tuned for visualizing the results in 3D, with the goal of providing the user with a clearer understanding of the moving parts.