[GRASS-user] v.external, postgis materialized views and projection

[Stefan Blumentrath]

Hi Donovan,

Did you try the suggestion from the error message to use the -o flag?
That overwrites the projection check and should link the data assuming the projection of your GRASS mapset.

Cheers
Stefan

From: grass-user <grass-user-bounces at lists.osgeo.org> On Behalf Of Donovan Cameron
Sent: tirsdag 17. august 2021 07:06
To: grass-user at lists.osgeo.org
Subject: Re: [GRASS-user] v.external, postgis materialized views and projection

On 2021-08-16 12:18 p.m., Phillip Allen wrote:
I am not sure about GRASS's quirks in respect to this problem but I do see in QGIS that in my views I often have to specifically CAST my geometries so QGIS can see the Z & M values:

example: SELECT b. sample_id, b. au_ppm, b. as_ppm, b. cu_ppm, ST_TRANSFORM(b.geom, 32718 )::geometry(LineStringZM,32718) FROM bore_hole b;

Tested on a new set of polygons and casted but it didn't make a difference. GRASS doesn't like ST_Transform on materialized views it looks like.

All the views are opening in QGIS fine and with their correct projection and geometry type (with and without casting to a specific type).


On Mon, Aug 16, 2021 at 1:10 PM Saulteau Don <sault.don at gmail.com<mailto:sault.don at gmail.com>> wrote:
When I use v.external to load a postgis materialized view it says the projection mismatches the Location but they are actually the same.

% v.external input="PG:host=localhost dbname=database" layer=table_1 output=t
ERROR: Projection of dataset does not appear to match current location.

      Location PROJ_INFO is:
      name: NAD83 / UTM zone 10N
      datum: nad83
      ellps: grs80
      proj: utm
      zone: 10
      no_defs: defined
      init: EPSG:26910

      Dataset PROJ_INFO is:
      name: NAD83 / BC Albers
      datum: nad83
      ellps: grs80
      proj: aea
      lat_0: 45
      lon_0: -126
      lat_1: 50
      lat_2: 58.5
      x_0: 1000000
      y_0: 0
      no_defs: defined

      Difference in: proj

      In case of no significant differences in the projection definitions,
      use the -o flag to ignore them and use current location definition.
      Consider generating a new location from the input dataset using the
      'location' parameter.

It looks like GRASS sees the projection from the source table used for the materialized view instead of the materialized views projection that was set in postgis using ST_Transform().

Is this normal for grass to see materialized views like this?




Donovan
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