L3DT Users' Community

I searched the forums, but didn't find any suggestions..


If I want to crop a Heightfield, is there a preferred way to do so?

For example, if I want to import real-world terrain to Torque using this tutorial: http://www.bundysoft.com/wiki/doku.php? ... :l3dt:srtm

But, instead of a 6001x6001 pixel heightmap, I'd like to crop it to 2048x2048. Photoshop editing the GeoTIF doesn't keep all of the metadata, so I need another way to crop. I can make a selection within L3DT, but don't seem to be able to crop it to that selection.

Any suggestions on tool/processes to edit GeoTIFs?

Also, if we resize a GeoTIF (ie from 6001 to 2048), should it also resize the Horizontal Scale? (ie, from 92.69 to 31.63)?

Thanks always for great tools!

Hi BigYak,

If you have the latest developmental build of L3DT, there is a fairly straightforward way to crop the heightfield:

• Use the select area mouse tool to select the desired area of the heightfield, or use the 'Edit->Select area...' to exactly specify the coordinates (remember: coordinate origin is at bottom-left of screen).
• Select 'Edit->Copy'.
• Select 'Edit->Paste as new layer'.
• When prompted for the layer name, enter "HF" to overwrite the current heightfield.

If you are not using the latest version of L3DT, you can do a similar trick, except that instead of copying and pasting, you need to export the selected area as a heightfield file, then re-import it as the heightfield. This approach may loose some of the metadata (not sure about this).

Also, if we resize a GeoTIF (ie from 6001 to 2048), should it also resize the Horizontal Scale? (ie, from 92.69 to 31.63)?

If you resize a heightfield from 6001x6001 to 2048x2048, the horizontal scale must increase by a factor of 2.93 for it to cover the same geographic area. The 'Operations->Heightfield->Resize heightfield' menu option will calculate and apply the correct horizontal scale for you.

Cheerio,
Aaron.

As always, Thanks Aaron!