Hi Rob,Points in a regular interval have always been a pain to create in postgis. I hope someone will write a decent linear_reference code for this some time soon.
Here's a way to do it:1) make a line out of your points (ST_SetSrid(ST_MakeLine(pointa, pointb), 27700))
2) add an M value to your line (ST_AddMeasure(geom, start, end))3) generate_series of intervals generate_series(0,floor(ST_Length(geom)/25.0)) < please check how to deal with that last segment smaller than 25 meter! 4) now you know how many points you need in every line you can use (ST_Line_Interpolate_Point(geom, (N*25)/St_Length(geom))
when N being the numbers you got from generate series in 3).Make sure not to put dimensional restrictions to your tables since ST_AddMeasure will want to add that extra M dimension.
Good luck!
Tom
On 25-7-2012 12:50, uk52rob wrote:
Hi,I have two point geometry tables, with which I need to compare a single point from the left table to all points in the right table.I need to extract X and Y co-ordinates (EPSG: 27700 OSGB36/British National Grid) every 25m along a fictitious line between the points in order to build a 'profile' of the land from a database containing height data.Does anyone have any 'best practise' or experience with this sort of project?Many thanks, Rob _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
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