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https://github.com/icholy/postgis-raster-examples
https://github.com/icholy/postgis-raster-examples
Last synced: 1 day ago
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- Host: GitHub
- URL: https://github.com/icholy/postgis-raster-examples
- Owner: icholy
- Created: 2014-03-10T16:37:22.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2014-03-10T17:09:03.000Z (over 10 years ago)
- Last Synced: 2024-04-15T14:25:38.367Z (6 months ago)
- Size: 160 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
Postgis Raster Examples
=======================
## Create Raster
* [ST_MakeEmptyRaster](http://postgis.net/docs/RT_ST_MakeEmptyRaster.html)
``` sql
SELECT ST_MakeEmptyRaster(
3, 3, -- width, height
0, 0, -- origin (top-left corner)
1, -1, -- scalex, scaley (pixel size, negative pixel size?)
0, 0, -- skewx, skewy
0 -- srid coordinate system (0 = None)
)
```
| st_makeemptyraster |
| -------------------|
| 0100000000000000000000F03F000000000000F0BF00000000000000000000000000000000000000000000000000000000000000000000000003000300 |
* [ST_MetaData](http://postgis.net/docs/RT_ST_MetaData.html)
``` sql
SELECT * FROM
ST_MetaData(
ST_MakeEmptyRaster(3, 3, 0, 0, 1, -1, 0, 0, 0) -- raster
)
```
upperleftx | upperlefty | width | height | scalex | scaley | skewx | skewy | srid | numbands
-----------|------------|-------|--------|--------|--------|-------|-------|------|----------
0 | 0 | 3 | 3 | 1 | -1 | 0 | 0 | 0 | 0
* [ST_PixelAsPolygons](http://postgis.net/docs/RT_ST_PixelAsPolygons.html)
``` sql
SELECT x, y, ST_AsEWKT(geom)
FROM
ST_PixelAsPolygons(
ST_MakeEmptyRaster(3, 3, 0, 0, 1, -1, 0, 0, 0) -- raster
)
```
x | y | st_askewkt
---|---|---------------------------------------
1 | 1 | POLYGON((0 0,1 0,1 -1,0 -1,0 0))
1 | 2 | POLYGON((0 -1,1 -1,1 -2,0 -2,0 -1))
1 | 3 | POLYGON((0 -2,1 -2,1 -3,0 -3,0 -2))
2 | 1 | POLYGON((1 0,2 0,2 -1,1 -1,1 0))
2 | 2 | POLYGON((1 -1,2 -1,2 -2,1 -2,1 -1))
2 | 3 | POLYGON((1 -2,2 -2,2 -3,1 -3,1 -2))
3 | 1 | POLYGON((2 0,3 0,3 -1,2 -1,2 0))
3 | 2 | POLYGON((2 -1,3 -1,3 -2,2 -2,2 -1))
3 | 3 | POLYGON((2 -2,3 -2,3 -3,2 -3,2 -2))
## Add Band to Raster
* [ST_AddBand](http://postgis.net/docs/RT_ST_AddBand.html)
* [Don't know what a band is?](http://edndoc.esri.com/arcsde/9.2/concepts/rasters/entities/rasterbands.htm)
``` sql
SELECT ST_AddBand(
ST_MakeEmptyRaster(3, 3, 0, 0, 1, -1, 0, 0, 0), -- the raster
'4BUI'::text, -- pixel type (http://postgis.net/docs/RT_ST_BandPixelType.html)
5, -- initial value
NULL -- nodata value (could be 0)
)
```
| st_addband |
|------------|
| 0100000100000000000000F03F000000000000F0BF000000000000000000000000000000000000000000000000000000000000000000000000030003000200050505050505050505 |
``` sql
SELECT *
FROM
ST_MetaData(
ST_AddBand(
ST_MakeEmptyRaster(3, 3, 0, 0, 1, -1, 0, 0, 0),
'4BUI'::text, 5, NULL
)
)
```
upperleftx | upperlefty | width | height | scalex | scaley | skewx | skewy | srid | numbands
-----------|------------|-------|--------|--------|--------|-------|-------|------|----------
0 | 0 | 3 | 3 | 1 | -1 | 0 | 0 | 0 | 1
``` sql
SELECT x, y, val
FROM
ST_PixelAsPolygons(
ST_AddBand(
ST_MakeEmptyRaster(3, 3, 0, 0, 1, -1, 0, 0, 0),
'4BUI'::text, 5, NULL
)
)
```
x | y | val
---|---|-----
1 | 1 | 5
1 | 2 | 5
1 | 3 | 5
2 | 1 | 5
2 | 2 | 5
2 | 3 | 5
3 | 1 | 5
3 | 2 | 5
3 | 3 | 5