I try to display elevation data using the triple Geoserver/Openlayer3/Cesium. It seems I have the same problem than http://stackoverflow.com/questions/25936968 and for now, I can not get a working solution!
I have done nearly the same gdal processing to obtain my picture pyramid and whatever the GeoserverTerrainProvider solution I use (BIL or with SLD) I get sharp cut elevation at tile edges (see:http://postimg.org/image/wy0j1ijnp/)
In the geoserver layer preview, my elevation image as bad tile border in ‘Tiling: Tiled’ mode (see: http://postimg.org/image/8sff9lw71/) but is ok in ‘Single tile’ mode. is GeoserverTerrainProvider requesting tiles from geoserver in a bad way? I must have missed something in the parameters I use!
Hello,
for me you don't need to use gdal_merge and should directly convert your asc files with gdal_translate. Moreover, you don't need to use a level of compression of 9 for gdal_translate because it generates temporary files for retile. You will win somme process time. For my conversions, I didn't use block size neither
Hi,
I have checked the man of gdal_translate how to use a set of asc files as input and sadly I did not found the good option but I tried with your suggestions: I removed the tile size and compression parameters without any enhancement!
I put it here http://pastebin.com/9b3izMDz
the first info is for the main-fullsize image created from all the asc files and the 2 last ones are from the 2 first tiles of the pyramid at level 1.
I do not think this is a gdal problem as I pushed my single “big” tiff as a layer in geoserver and the result is quite the same: I have got sharp cuts in elevation at tile edges. So it seems to be a geoserver tile serving problem or a bad request from the GeoserverTerrainProvider to geoserver.
Now, I think GeoserverTerrainProvider is the culprit as I tested my geoserver elevation layer in this application https://github.com/parkerabercrombie/worldwind-examples and it is displayed correctly… still searching for a solution!
Ok one last test: could you use GeotiffTranslate on your big tif and then make a pyramid from result in order to save the translated pyramid in geoserver and test again with the plugin?
Is it possible to have your source (asc file) from France?
Dans ce cas je testerai et je reviendrai vers toi. (If possible, I'll test and make a return)
Hello, after somme work, I found that with the following process, it seems to work well:
1°) convert your asc into geotiff and change the source srs to EPSG:4326 with an interpolation better than bilinear. If you move all your asc files in a folder and your console is in this folder then the command is:
gdalwarp -ot Int16 -s_srs "EPSG:2154" -t_srs "EPSG:4326" -dstnodata -32762 -r cubicspline -multi -co "TILED=YES" -co "COMPRESS=DEFLATE" -co "ZLEVEL=6" *.asc outFolder/gray.tif
2°) you should have a gray.tif which weights 110 Mio; Now you can make your pyramid from this tif:
gdal_retile.py -v -r bilinear -levels 3 -ps 2048 2048 -ot Int16 -co "TILED=YES" -co "COMPRESS=DEFLATE" -co "ZLEVEL=6" -targetDir pyramidFolder outFolder/gray.tif
But I do not understand why this gdal script corrects the problem or what in my previous script generates the glitches at tile edges.
I still have bad elevation data at the edges the elevation map (I only have the elevation for France) (see: http://postimg.org/image/6i5fwzs8t/ ). May be you have a solution for this problem?
My presumptions:
* Cesium doesn't work with Lambert 93 (only EPSG 4326 and web mercator)also some conversions must be made by geoserver => big risk of integrity during these operations
* Maybe each asc use same reference but there is no smoothing operation between tile with your method. I forced the smoothing by generate one sole tif file with cubicspline interpolation