[GRASS-dev] problem with GridModule

Pietro peter.zamb at gmail.com
Thu Nov 19 00:16:26 PST 2015

Hi Anna,

soory for the delay...

On Mon, Nov 16, 2015 at 3:23 PM, Anna Petrášová <kratochanna at gmail.com> wrote:
> On Mon, Nov 16, 2015 at 8:28 AM, Markus Neteler <neteler at osgeo.org> wrote:
>> On Tue, Nov 10, 2015 at 7:58 PM, Anna Petrášová <kratochanna at gmail.com>
>> wrote:
>> > Maybe some bug in the pygrass raster library?
>> Looks like a race condition?
> I don't understand why would that happen, the patching done with pygrass
> raster library is not running in parallel.

Yes I have to investigate more on this to understand what it is not working...

> A workaround I currently use is to patch the rasters using r.patch, which is
> in the case of viewsheds OK (the overlaps are the same), however in other
> cases such as interpolation, the overlaps are different and r.patch won't
> patch the rasters as desired, that's why the GridModule is using pygrass
> raster library I assume.

I've modified r.tile to split and merge using an optional parameter
for the overlap (perhaps I should create just a new module r.untile
instead of adding a new flag in r.tile...).
The approach it is much faster than the actual implementation of
r.patch because minimize reading disk operations since we are not
merging general raster maps with undefined bboxes but  well known
Unfortunately the implementation still experimental and has some
problems. I will not able to work on this before next year... maybe I
can put the modified version of r.tile in the sandbox repo.

Let me know.


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