[gdal-dev] Support for Terrain-RGB

[Lars Ahlzen]

On 05/01/2026 21:42, Even Rouault wrote:
>
> Le 05/01/2026 à 22:27, Lars Ahlzen a écrit :
>> Hi Even,
>>
>> On 05/01/2026 14:50, Even Rouault wrote:
>>> I would rather see that as a standalone TerrainRGB raster driver, 
>>> leveraging the PNG driver underneath.
>>
>> That was my original thought as well. Then, after thinking about 
>> different use cases I thought adding a gdaldem mode would allow for a 
>> wider range of workflows.
>>
>> That said, you probably have a better idea of what would work best 
>> for GDAL as a whole, so I can look in that direction.
>
> The rationale behind suggesting a driver rather than a new mode to 
> gdaldem is that gdaldem modes are agnostic of the output format. Here 
> it is really a file format issue. 

Being format agnostic might actually be an advantage though. While the 
encoding is commonly used with PNG tiles, other RGB raster formats 
should work as well and may even be advantageous. For example, I've used 
a terrain-RGB encoded GeoTIFF as an intermediary format, from which 
tiles were later generated using gdal2tiles.

- Lars