Contents
- 1 How to convert PostGIS geometry to St asraster?
- 2 What is the function St _ 3ddistance in PostGIS?
- 3 How are spatial aggregate functions used in PostGIS?
- 4 When to skip the St _ intersection call in PostGIS?
- 5 Which is the enhanced version of PostGIS St Union?
- 6 What is the name of the constraint on a raster column?
How to convert PostGIS geometry to St asraster?
ST_AsRaster — Converts a PostGIS geometry to a PostGIS raster. raster ST_AsRaster( geometry geom, raster ref, text pixeltype, double precision value=1, double precision nodataval=0, boolean touched=false);
What is the function St _ 3ddistance in PostGIS?
ST_3DDistance- For geometry type Returns the 3-dimensional cartesian minimum distance (based on spatial ref) between two geometries in projected units. This method implements the SQL/MM specification. SQL-MM ?
What does St _ buffer-( t ) do in PostGIS?
ST_Buffer- (T) For geometry: Returns a geometry that represents all points whose distance from this Geometry is less than or equal to distance. Calculations are in the Spatial Reference System of this Geometry. For geography: Uses a planar transform wrapper.
How are spatial aggregate functions used in PostGIS?
PostGIS Aggregate Functions The functions given below are spatial aggregate functions provided with PostGIS that can be used just like any other sql aggregate function such as sum, average. ST_3DExtent- an aggregate function that returns the box3D bounding box that bounds rows of geometries.
When to skip the St _ intersection call in PostGIS?
In many situations you know the intersection of 2 geometries without actually computing an intersection. In these cases, you can skip the costly ST_Intersection call. Cases like this: This kind of question comes up a lot: As discussed in stackexchange Acquiring ArcGIS speed in PostGIS
Is there a St reclass function in PostGIS?
This raster question comes up quite a bit on PostGIS mailing lists and stack overflow and the best answer often involves the often forgotten ST_Reclass function that has existed since PostGIS 2.0.
Which is the enhanced version of PostGIS St Union?
Enhanced: 2.1.0 ST_Union (rast) (variant 1) unions all bands of all input rasters. Prior versions of PostGIS assumed the first band. Enhanced: 2.1.0 ST_Union (rast, uniontype) (variant 4) unions all bands of all input rasters.
What is the name of the constraint on a raster column?
Generates constraints on a raster column that are used to display information in the raster_columns raster catalog. The rastschema is the name of the table schema the table resides in.
How do I adjust the size of the raster?
The parameters of the pixel size ( scalex & scaley and skewx & skewy) of the resulting raster will be adjusted to fit the extent of the geometry.