Working with large files

[JarrodBWong]

"Once this tileset is generated it can be turned into a GDAL Virtual Raster dataset for creating the next zoom level down (e.g. level 17). Repeating this process until the lowest zoom level is created means that the resampling is much more efficient (e.g. level 0 would be created from a VRT representation of level 1). Because terrain tiles are not a format supported by VRT datasets you will need to perform this process in order to create tiles in a GDAL DEM format as an intermediate step. VRT representations of these intermediate tilesets can then be used to create the final terrain tile output."

I do not understand what I am supposed to be doing for the intermediate step when processing level by level. After I create the first level of terrain tiles how or what do I point to for the next level?

[JarrodBWong]

I think this might be ctb-export command? When I try to load my zoom level 15 i get the error "argument list too long".

[liberostelios]

I had a similar issue and here is what i did:

1. Construct the terrain of level 18 from the original tiff: ctb-tile --output-dir ./whatever --start-level 18 --end-level 18 original.tif
2. Create the GDAL tileset for the same level: ctb-tile --output-format GTiff --output-dir ./whatever-tiff --start-level 18 --end-level 18 original.tif
3. Build the VRT for this level: gdalbuildvrt level18.vrt ./whatever-tiff/18/*/*.tif
4. Construct the terrain of level 17 from the new VRT: ctb-tile --output-dir ./whatever --start-level 17 --end-level 17 level18.vrt

Now, repeat steps 2 to 4 for each additional level. I guess it helps if you can make a bash script for the whole process.

Keep in mind that you can avoid repeating this process for all levels, though. You can find the last level that does not "break", create that level's tileset and VRT (steps 2 and 3) and then create the rest of the levels from that VRT. For instance, i got errors on level 8, so i ran steps 2 and 3 for level 9 and, finally, ran a ctb-tile --output-dir ./whatever --start-level 8 --end-level 0 level9.vrt.

[gongzk]

@liberostelios Thanks, it is work! But in step 3, it is gdalbuildvrt level18.vrt ./whatever-tiff/18/*/*.tif

[ibreathebsb]

I had a similar issue and here is what i did:

1. Construct the terrain of level 18 from the original tiff: ctb-tile --output-dir ./whatever --start-level 18 --end-level 18 original.tif
2. Create the GDAL tileset for the same level: ctb-tile --output-format GTiff --output-dir ./whatever-tiff --start-level 18 --end-level 18 original.tif
3. Build the VRT for this level: gdalbuildvrt level18.vrt ./whatever-tiff/18/*/*.tif
4. Construct the terrain of level 17 from the new VRT: ctb-tile --output-dir ./whatever --start-level 17 --end-level 17 level18.vrt

Now, repeat steps 2 to 4 for each additional level. I guess it helps if you can make a bash script for the whole process.

Keep in mind that you can avoid repeating this process for all levels, though. You can find the last level that does not "break", create that level's tileset and VRT (steps 2 and 3) and then create the rest of the levels from that VRT. For instance, i got errors on level 8, so i ran steps 2 and 3 for level 9 and, finally, ran a ctb-tile --output-dir ./whatever --start-level 8 --end-level 0 level9.vrt.

hi it's been a long time,but how do i deal with mulitple tif input files?