[GRASS-dev] how to reproject a raster map with absolute numbers without losing data

[Moritz Lennert]

On 01/12/16 08:49, Markus Metz wrote:
>
> r.to.vect converts only non-null cells, no mask needed, at least for me
> in trunk.

Weird, I waws convinced that I saw otherwise before, but now I can 
confirm. Sorry for the noise...


>>
>> >2. reproject these vector points to the target location
>>
>> I locally modified v.proj to add a 'Don't build topology' flag.
>>
>> Is there any indication against this ?
>
> No.

Ok, added in trunk with r69960.


>> >
>> >The method options of r.in.xyz <http://r.in.xyz> could be added to
> r.proj for spatial
>> >aggregation, but that would mean that most of the code of r.in.xyz
> <http://r.in.xyz>
>> >would
>> >need to be copied to r.proj, then adapted. That would be an interesting
>> >enhancement, also considering that gdalwarp offers as resampling
>> >methods
>> >near, bilinear, cubic, cubicspline, lanczos, average, mode, max, min,
>> >med,
>> >Q1, Q3.
>>
>> But it doesn't offer sum....
>
> True, but it offers statistical aggregates. And for average, you need to
> have the sum internally anyway, then divide by the cell count (number of
> source cells falling into the current target cell), at least this is how
> I imagine how average would be calculated.

True ;-)

Moritz