View Full Version : Elevation Data as Texture?
07-05-2007, 05:40 AM
Is there a way to get the Elevation Tiles that are used a the source for the Elevation Model to show up as TextureTiles? For example could you rig up a TiledImageLayer with the SRTM bil things as a source? Specifically, I would want the Elevation tiles to show up in a texture tile that I could then use for rendering. I assume they would be 16bit values, but they could be packed in one of several texture formats if the data was available.
07-05-2007, 08:59 AM
I dont think there is a straightforward way to accomplish this.
You could probably setup a special Retreiver class for such a layer. It would then have to process the appropriate SRTM data to create texture tiles on the fly - as if they would have been read from the cache or downloaded.
Please, let us know if you do any progress in that direction :rolleyes:
07-05-2007, 09:02 AM
this feature has already been developped for .net ww.
the thread is here : http://forum.worldwindcentral.com/showthread.php?t=3523
I think it will be possible to developp such plugin for ww java.
the conversion between 16bit data to color map is not a difficult, moreover, data are not between 0 and 65536 but more 0 and 7000 if i remember.
I have not a lot a time but i will be interresting to follow the development of a kind of this plugin.
07-05-2007, 09:26 AM
Salut Pierrick !
It is not very clear from the refered thread what you managed to do... and it dates back two years. Could you post an update and some precisions ?
BTW: elevation data for Earth range from -11000m to +8850m (see globes.EarthElevationModel)
07-05-2007, 09:43 AM
ok, let's me explain ;)
I don't remember that this thread is so old :)
At this time, i have made a java program to convert .bil tile to .jpg tile.
Fortyfive had setup a server to people have these tiles. This previous plugin so just add a serveur to image.xml to have view srtm colored data.
I don't know if the fortyfive serveur is ever up, but if yes, it will be possible to get theses tiles.
I remember also that srtm data set had been renewed in the time.
However, as my convert code was in java, it will be possible to had it with a lot of modification in ww java.
Don't hesitate to mp me for more informations :)
07-05-2007, 05:27 PM
Actually, let me restate to be clear. The elevation data is already on the client java side, in the elevation model code for WW. Its being used by the stuff to tesselate the mesh. What I want to do is 2 things. First, use the already present level of tesselation, but grab it as either raw bits, which I would make into a texture, and Second, once the first part works, be able to request other levels of tesselation for those bits. This 16bit pseudogray level texture thing would be useful for things like rendering with coloring based on elevation. It is completely unnecessary and kind of wasteful to impose a jpeg intermediary step. It is however possible that because of the tile subdivision system in place, it would be complicated to render this way without generating seam like effects in the output, because texture pixels on tile borders would not have correct averaging. In reading about the .net version on line, they seem to have handled this, so Im wondering where the java version is in this respect.
07-05-2007, 07:15 PM
You can do the texture generation from the retreiver.
Elevation data from SRTM can be accessed simply by Globe.getElevation(lat, lon).
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