[mkgmap-dev] [PATCH v4] contours

Fri Jul 10 18:01:24 BST 2009

Dear Clinton,

Clinton Gladstone schrieb:
> I was able to successfully compile a small area using ASTER tiles. The
> resulting map looked correct.
>
> However, I was not able to compile a larger area. I tried
> Rheinland-Pfalz as downloaded from Geofabrik. If I understood the
> error message and the coding correctly, this is because
> Rheinland-Pfalz crosses the 1x1 ASTER tile boundaries: a map tile
> compiled with your patch apparently must lie completely in the 1x1
> ASTER boundary.
>
> Is this correct?
>   
yes, corrently the code has this restriction.
> If so, this would be an unfortunate limitation. It would require maps
> to be split at exactly the 1 degree lat/long boundaries.
>
> Or is this something that can be eventually coded around? I suppose
> that this is less of an issue with the 5 degree CGIAR data.
>   
There are several possibilities to "code around" this:
- generate the contours separately for each DEM-tile (easy to implement, 
but wouldn't be nice at the border)
- load DEM data from more than one DEM tile (nice contours, but more 
complicated to implement)
- write a little utility to paste GeoTIFF files together

This is actually one of the reasons I added support for CGIAR.

Best wishes
Christian