How can I extend an existing terrain set?

[greuff]

Say I have an existing terrain directory which was generated using ctb-tile and a few source DEMs. How can I cover more area with ctb-tile by adding the information from additional DEM files? The only way I figured out to do this is to recalculate everything with all source DEMs, which of course takes a very long time. I also tried the -R switch to not overwrite existing files, but then I get holes in the terrain at the tile borders. I hope there is a way to do so.

[raycrummey]

I have the same question as well. I am using a VRT. I think one option is to create a VRT with just the new data (VRTnew) and create a VRT with all the data (VRTall).

Run ctb-tile on the VRTnew and output it to the same directory. Now, run ctb-tile with the -l option on VRTall to create your new layer description file to include all the tiles.

This should work well if your VRTnew is adding tiles to the border of your original dataset.