[GRASS-user] Best workflow

[patrick s.]

Paul, a short comment.

Depending on the information you need to process it might be enough to match the rasterdata to the centroid of the polyons, which is not having issues of overlaps with multiple tiles.

Regards,
Patrick

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Message: 1
Date: Fri, 24 Jun 2016 11:34:47 +0200
From: Paul Meems<bontepaarden at gmail.com>
To: GRASS user list<grass-user at lists.osgeo.org>
Subject: Re: [GRASS-user] Best workflow
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	<CAHNf2YScObkXgB1KrBiJnL4YaagU5QdvfnmzRungsCOQyG4Akw at mail.gmail.com>
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Thanks Stefan,

I didn't thought of gdalbuildvrt. I'll try that option.
The polygons do not overlap and I'm not sure about the height data. Perhaps
they overlap a bit.

What I need to do in GRASS is:

    - call r.slope.aspect to calculate the slope and aspect. I had planned
    doing this for every polygon but when I'm going to use gdalbuildvrt I can
    do it for the whole dataset in one time.
    Is that a good choice? The height data spans The Netherlands and has
    0.5m resolution. Can GRASS handle such a big dataset?
    - Next command is r.mapcalc. This can be done on a subset or on the
    whole dataset at once.
    - Then I need to call r.to.vect. I think it is best to do this for a
    subset because I only need the part within the polygon. I think I can set
    the region to the polygon and then call r.to.vect to speed this up, right?
    - Then I need to clip with the border and export this vector dataset to
    PostGIS.

With the above workflow I don't think I need to convert the polygons to
raster first, right?
I'm readinghttps://grasswiki.osgeo.org/wiki/PostGIS  and I'm using GRASS v7
so if I understand it correctly I can link a PostGIS table using v.external
Can I then loop through each feature and perform the above workflow and
also update a field in PostGIS called something like 'processed' and set it
to True?
And am I right I can do this all using Python? I'm running Ubuntu server so
no GUI available.

Thanks

Paul