The only reason I can think why QGIS and DBeaver would show something different
is how they are projecting.
I’m guessing they are both projecting to Web Mercator or some such thing to
overlay your geometry on the map, and their assumptions about SRID 28992 are
different.
I’d try transforming both your geometries to 4326
ST_Transform( ST_Polygon(…), 4326)
I’m guessing whatever spatial projecting they do from 4326 should be consistent.
Alternatively ditch the map overlay and then maybe they won’t try to reproject.
From: Eloi Ribeiro <m...@eloiribeiro.eu>
Sent: Thursday, March 21, 2024 11:47 AM
To: PostGIS Users Discussion <postgis-users@lists.osgeo.org>
Subject: RE: How to properly rotate a raster
Hi Regina and all,
I' seeing different things depending on what application I use. On QGIS the
rotated raster appears smaller in width and height. On DBeaver, both rotate,
although in different directions.
-- Create raster from polygon (black line)
DROP TABLE IF EXISTS public.rast_not_rotated;
CREATE TABLE public.rast_not_rotated AS
SELECT ST_AsRaster(t.geom,1000,1000,'8BUI',1,0) AS rast
FROM (SELECT ST_GeomFromText('POLYGON((166989.36462303242
505764.77048559673,
166996.25788353998 505576.476318614,
167265.54134611748 505585.94966528506,
167258.67088940175 505774.2438322678,
166989.36462303242
505764.77048559673))',28992) geom) t;
ALTER TABLE public.rast_not_rotated ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_not_rotated_rast_gist ON public.rast_not_rotated USING gist
(st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_not_rotated'::name,'rast'::name);
-- rotate previous raster (blue)
DROP TABLE IF EXISTS public.rast_rotated_from_raster;
CREATE TABLE public.rast_rotated_from_raster AS SELECT ST_SetRotation(rast,
-0.5) rast FROM public.rast_not_rotated;
ALTER TABLE public.rast_rotated_from_raster ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_rotated_from_raster_rast_gist ON
public.rast_rotated_from_raster USING gist (st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_rotated_from_raster'::name,'rast'::name);
-- rotate polygon and then save as raster (red)
DROP TABLE IF EXISTS public.rast_rotated_from_vector;
CREATE TABLE public.rast_rotated_from_vector AS
SELECT ST_AsRaster(t.geom,1000,1000,'8BUI',1,0) AS rast
FROM (SELECT ST_Rotate(
ST_GeomFromText('POLYGON((166989.36462303242
505764.77048559673,
166996.25788353998 505576.476318614,
167265.54134611748 505585.94966528506,
167258.67088940175 505774.2438322678,
166989.36462303242
505764.77048559673))',28992)
,-0.5, 166989.36462303242,
505764.77048559673) geom) t;
ALTER TABLE public.rast_rotated_from_vector ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_rotated_from_vector_rast_gist ON
public.rast_rotated_from_vector USING gist (st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_rotated_from_vector'::name,'rast'::name);
On QGIS.
black line - raster from polygon
red - the rotated polygon and then converted to raster
blue - rotated raster, different from how it is displayed in DBeaver.
On DBeaver this is how it shows the rotated raster.
On DBeaver this is how it shows the rotated polygon and then converted to
raster.
On Tuesday, March 19th, 2024 at 14:58, Regina Obe <l...@pcorp.us
<mailto:l...@pcorp.us> > wrote:
An easier way to compare what is happening is to look at the ST_Polygon output
of the two. https://postgis.net/docs/en/RT_ST_Polygon.html
I’m thinking the confusion (which I had thought myself) is that the width and
height is measured against the X y axis, but now I think about it, I think it’s
measured along the skew so width and height would remain the same in both
cases. In the case of your polygon you rotate and then save as raster, the new
raster is axis aligned and so there you do see the width and height change.
So when I run this query:
SELECT ST_Polygon(r1.rast) AS orig_geom_rast, ST_Polygon(r2.rast) AS
rotated_geom_rast, ST_Width(r1.rast) AS orig_width, ST_Width(r2.rast) AS
rotated_width
FROM (SELECT rast FROM rast_not_rotated) AS r1,
(SELECT ST_SetRotation(rast, -0.5 ) AS rast FROM rast_not_rotated) AS r2;
The dashed polygon is the original polygon and the filled in one is after you
rotate the raster. In both cases the ST_Width and ST_Height do not change so
that’s not a good measure of what is going on.
From: Eloi Ribeiro <m...@eloiribeiro.eu <mailto:m...@eloiribeiro.eu> >
Sent: Tuesday, March 19, 2024 6:56 AM
To: PostGIS Users Discussion <postgis-users@lists.osgeo.org
<mailto:postgis-users@lists.osgeo.org> >
Subject: RE: How to properly rotate a raster
Hi all,
Here an example with the code.
If you compare rast_rotated_from_raster with rast_rotated_from_vector, the
latest is rotated as expected and the first is not.
I guess, I must be doing something wrong when creating rast_rotated_from_raster.
Any guess?
-- non rotated raster
DROP TABLE IF EXISTS public.rast_not_rotated;
CREATE TABLE public.rast_not_rotated AS
SELECT ST_AsRaster(t.geom,1000,1000,'8BUI',1,0) AS rast
FROM (SELECT ST_GeomFromText('POLYGON((166989.36462303242
505764.77048559673,
166996.25788353998 505576.476318614,
167265.54134611748 505585.94966528506,
167258.67088940175 505774.2438322678,
166989.36462303242
505764.77048559673))',28992) geom) t;
ALTER TABLE public.rast_not_rotated ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_not_rotated_rast_gist ON public.rast_not_rotated USING gist
(st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_not_rotated'::name,'rast'::name);
-- rotate previous raster
DROP TABLE IF EXISTS public.rast_rotated_from_raster;
CREATE TABLE public.rast_rotated_from_raster AS SELECT ST_SetRotation(rast,
-0.035162353342492736) rast FROM public.rast_not_rotated;
ALTER TABLE public.rast_rotated_from_raster ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_rotated_from_raster_rast_gist ON
public.rast_rotated_from_raster USING gist (st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_rotated_from_raster'::name,'rast'::name);
-- rotate polygon and then save as raster
DROP TABLE IF EXISTS public.rast_rotated_from_vector;
CREATE TABLE public.rast_rotated_from_vector AS
SELECT ST_AsRaster(t.geom,1000,1000,'8BUI',1,0) AS rast
FROM (SELECT ST_Rotate(
ST_GeomFromText('POLYGON((166989.36462303242
505764.77048559673,
166996.25788353998 505576.476318614,
167265.54134611748 505585.94966528506,
167258.67088940175 505774.2438322678,
166989.36462303242
505764.77048559673))',28992)
,-0.035162353342492736, 166989.36462303242,
505764.77048559673) geom) t;
ALTER TABLE public.rast_rotated_from_vector ADD COLUMN rid SERIAL PRIMARY KEY;
CREATE INDEX rast_rotated_from_vector_rast_gist ON
public.rast_rotated_from_vector USING gist (st_convexhull(rast));
SELECT AddRasterConstraints('public'::name,
'rast_rotated_from_vector'::name,'rast'::name);
Eloi
On Monday, March 18th, 2024 at 19:11, Eloi Ribeiro <m...@eloiribeiro.eu
<mailto:m...@eloiribeiro.eu> > wrote:
Hi Regina and all,
Elaborating a bit more. I have a vector layer consisting of a rectangle (farm
plot), and this rectangle is subdivided into several (polygons) stripes
parallel to the outer edge of the rectangle. I want to produce a raster where
the rectangle and stripes long edges are parallel to the latitude line.
Using ST_Rotate(geom, -0.035, x, y) in all vector layers together with
ST_AsRaster(), I managed to get what I want. Good.
Nevertheless, if I first produce the raster and then try to rotated it using
ST_SetRotation(rast, -0.035), I barely see any rotation. In this step, I must
be doing something wrong.
I would like to first rasterize vector and then rotate the raster. Instead of
rasterize non rotated vector and then, again rasterize rotated vector.
The change in size (width and height), I mentioned in my first message, was
while testing with 0.5 rad, not with -0.035 rad.
-- input raster
SELECT ST_Width(rast), ST_Height(rast), ST_SkewX(rast) FROM plot_3;
-- st_width | st_height | st_skewx
-- ----------+-----------+----------
-- 1000 | 1000 | 0
-- output raster of ST_SetRotation(rast, -0.035162353342492736)
SELECT ST_Width(rast), ST_Height(rast), ST_SkewX(rast) FROM
plot_3_rotated_from_raster;
-- st_width | st_height | st_skewx
-- ----------+-----------+----------------------
-- 1000 | 1000 | 0.006952538312005269
-- output raster of ST_SetRotation(rast, -0.035162353342492736)
SELECT ST_Width(rast), ST_Height(rast), ST_SkewX(rast) FROM
plot_3_rotated_from_vect;
-- st_width | st_height | st_skewx
-- ----------+-----------+----------
-- 977 | 964 | 0
-- output raster of ST_SetRotation(rast, -0.5)
SELECT ST_Width(rast), ST_Height(rast), ST_SkewX(rast) FROM
plot_3_rotated_from_raster_05;
-- st_width | st_height | st_skewx
-- ----------+-----------+---------------------
-- 1000 | 1000 | 0.09481479675190897
Cheers,
Eloi
On Monday, March 18th, 2024 at 14:01, Regina Obe <l...@pcorp.us
<mailto:l...@pcorp.us> > wrote:
By size, what do you mean exactly? It would change the width and height.
What are you expecting rotation to do. Perhaps you can give example out of the
below and some sample
ST_Width, ST_Height, ST_SkewX before and after and what you were expecting.
https://postgis.net/docs/en/RT_ST_SetRotation.html
From: Eloi Ribeiro <m...@eloiribeiro.eu <mailto:m...@eloiribeiro.eu> >
Sent: Monday, March 18, 2024 4:57 AM
To: PostGIS Users Discussion <postgis-users@lists.osgeo.org
<mailto:postgis-users@lists.osgeo.org> >
Subject: How to properly rotate a raster
Hi all,
I need to rotate a raster, for that I'm using the function ST_SetRotation, like
so:
CREATE TABLE plot_3_rotated AS
SELECT ST_SetRotation(rast, 0.03516235334249185) rast
FROM plot_3;
But I see that is not producing the expected results and is changing size of
the raster. What am I doing wrong?
Cheers,
Eloi
