[GRASS-dev] Filter STDS by spatial index

[Paulo van Breugel]

On December 14, 2022 15:24:28 Stefan Blumentrath 
<Stefan.Blumentrath at gmx.de> wrote:

> Hei,
>
> I do have a use case where I would like to filter maps in a STRDS by 
> spatial extent before e.g. t.rast.univar processes all registered maps.
> In particular, I want to process only maps from a STRDS that intersect with 
> the current computational region.
>
> The reason is that the maps registered in the STRDS are collections of 
> single scenes of satellite images or collections of smaller mosaics that 
> cover only parts of the total extent of the STRDS.
>
> Currently, that does not seem to be supported by TGIS, and I see two 
> options to address that:
>    a) patch the scenes together with a given granularity (e.g. daily mosaics), 
>    leave GRASS GIS functions untouched and hope that there is some coverage 
>    for reasonable region settings. or:
>    b) add a spatial filter to the "get_registered_maps"[1] function in 
>    abstract_space_time_dataset.py, and then subsequently flags to relevant 
>    modules that make use modified function...
>
> For b) I would think that the most efficient way to handle it would be to 
> add a where clause like it was done for the semantic labels? In that case, 
> it may make sense to add an index for north, south, east, and west too, no? 
> Maybe also top and bottom...
>
> My main question, however is if my case is just a corner case, or does some 
> sort of spatial filteing possibility make sense in general / more broadly...

It seems a bit of a corner case, but in fact something I could use, of I 
understand it right.

>
> Any feedback is much appreciated, esp. before I evtl. start working on b).
>
> Kind regards,
> Stefan
>
> 1) 
> https://github.com/OSGeo/grass/blob/main/python/grass/temporal/abstract_space_time_dataset.py#L1604
>
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