Display terrain (elevation, geometric height, DTM): mountains, etc.
Visualize 3D terrain instead of the sphere only.
Note: this involves preparing and hosting of a separate tileset which will represent the geometric height by the values of pixels (greyscale). Triangles in the WebGL Earth can be then adjusted by the relevant height (pixel value) loaded from the texture (tile) at given lat/lon position.
Possible datasets to use:
- GTOPO30: global digital elevation model (DEM) ~ 1km x 1km - http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info
- SRTM3: Shuttle Radar Topography Mission ~ 90m x 90m - http://www2.jpl.nasa.gov/srtm/
- CGIAR: 90m
- ASTER GDEM: Aster Global Digital Elevation Model ~ 30m x 30m -
Rendering of such tiles can be done with GDAL / GDAL2Tiles / MapTiler / MapTiler Cluster. Ideally into spherical mercator tiles with 16bit grayscale PNG.
Such functionality is not going to be supported by every graphic card, because WebGL vertex shader needs to read a texture:
"The WebGL specification says that you can query WebGL to see how many vertex textures are supported - and the answer can legally be (and often is) zero...in which case you don't have vertex textures and you have to figure another way around the problem."
n = gl.getParameter(MAX_VERTEX_TEXTURE_IMAGE_UNITS);
Demo of similar terrain LoD streaming:
matt wilkie commented
+10 if I could. Lack of 3rd party terrain sources is our oldest and bigget complaint with Google Earth. I have a better elevation model for all of Northern Canada than GE provides, and in spite of several attempts to give it to them it remains in storage (http://www.maphew.com/Projects/Canada_50k_Digital_Elevation_Model). I'm positively excited at the prospect of an alternative, that can operate disconnected from the 'net, and an open source one at that is just ... *delightful*.
Bjørn Sandvik commented
Would be nice if you could add your own DEM tiles as well as image tiles.
A source of pretiled terrain data is NASA WorldWind servers. It contains SRTM + Aster terrains.