[postgis-devel] ST_GetValues()

[Regina Obe]

> >> How about just overloading the name ST_Force3DZ, ST_Force3DM cause
> >> that's essentially what you are doing here isn't it?
> 
> No, no more overloading, that just makes things less clear.
> 
[Regina Obe] Yah I figured you wouldn't go for that but thought I'd throw it
out there :)

> > How about ST_PopulateZ and ST_PopulateM ?
> 
> I had originally thought something like that. I'm fine w/ those. I think I
had
> ST_CopyZ / ST_CopyM in my notes.
> 
 [Regina Obe] 
NOOO hate those. Populate reminds me too much of our management functions
populate_geometry and is many characters to type.
ST_Copy just feels wrong as it feels like both the source and target should
be the same family of thing.


> > Or even ST_SetZ and ST_SetM.
> 
> Not feeling these ones.
> 
> > For the latter we also have an open ticket requesting to extend the
> > functionality of ST_SetZ/ST_SetM to allow getting the Z/M values from
> > some other computation. In this case the computation would be
> > extracting the value from a Raster, if I Understand correctly.
> >
[Regina Obe] 
I like ST_SetZ and ST_SetM the best.  I think it more follows the other
function naming for setters like ST_SetPoint and friends
(http://postgis.net/docs/manual-dev/ST_SetPoint.html)


> > Or .. don't we have functions that "draw" a raster into a
> > "vector/geometry canvas" ? In that case we could have them accept a
> > non-empty canvas, to "draw into a pre-existing geometry", with some
> > draw operation (multiply/add/replace/subtract..).
> > I've some resemblance of implementing that kind of "drawing"
> > in the CHIP type times...
> >
> > --strk;
> > 
[Regina Obe] We  have a function that burns geometries into a raster - it's
called ST_SetValues -
http://postgis.net/docs/manual-dev/RT_ST_SetValues.html
Then there is ST_DumpAsPolygons which converts a raster to a set of geomvals
(geom, value).   -
http://postgis.net/docs/manual-dev/RT_ST_DumpAsPolygons.html

Paul's new function will largely replace the use of this function.  Common
use case of this function was

ST_DumpAsPolygons(ST_Clip(raster,ref_geom))

And then use the val of the geomvals returned to reconstitute a new geometry
with Z/M (borrowed from the values)