Changes between Version 59 and Version 60 of PostGIS_Raster_SoC_Idea_2012/Distance_Analysis_Tools
- 07/01/12 22:05:25 (12 months ago)
v59 v60 644 644 You pass a raster description based on parameter (similar to ST_AsRaster) or an existing raster and the name of a table (with the schema) and a geometry column (much like in ST_Count but passing a geometry column instead of a raster column) containing the points you want to compute the distance from for every pixels. Those points do not have to be in the raster extent and there can be as many as you want since you will be using the KNN index to find the nearest one.<br> 645 645 Generally you won't want to UPDATE an existing raster but rather create a new one based on an existing raster or even better an existing raster coverage. More something like:<br><br> 646 CREATE TABLE distcoverage AS 647 SELECT rid, ST_MapalgebraFct(rast, 'euclidean_fct(list of parameters including the table name and column name of the geometry table)'::regprocedure) rast 646 CREATE TABLE distcoverage AS 647 SELECT rid, ST_MapalgebraFct(rast, 'euclidean_fct(list of parameters including the table name and column name of the geometry table)'::regprocedure) rast 648 648 FROM myexistingcoveragetable<br><br> 649 649 We should afet encapsulate the ST_Mapalgebra function with a name and parameter list corresponding to a series of ST_EucledianDistance functions (some taking raster creation parameter, some taking a reference raster).