[postgis-devel] wktraster ST_ConvexHull

[Pierre Racine]

>> One problem I see is that people see the result of ST_Dump as simple polygons when the result of
>ST_AsPolygon is not necessarily simple polygons. You get simple polygons only when you add the
>'CONTIGUOUS' keyword to the function (ST_AsPolygon(raster, integer, 'CONTIGUOUS')).
>>
>
>Then, the 'CONTIGUOUS' keyword is used only when you want single
>polygons in the output geometry (I suppose this terminology, with
>CONTIGUOUS word, comes from any GIS field...). I think this could be a
>problem, because GDALPolygonize allways generates standard WKB
>polygons. I've used this function for st_aswktpolygon. So, the
>function always works as if 'CONTIGUOUS' option is specified. Should
>we codify our own polygonize function? We had this discussion some
>months ago...

If GDAL is producing only contiguous polygon then our (new) ST_Dump function should do the same and forget about the 'CONTIGUOUS' variant.

>>>Getting to names -- ST_AsWKTPolygon should not start with an ST_ if it is
>>>not intended for end user use.
>>
>> Jorge, could we rename ST_AsWKTPolygon to RasterAsWKTPolygon?
>>
>
>Of course. We should avoid "ST" in functions not intended for end-user
>use. But, do we all agree on that name? Seems Regina prefer a name
>like "ExtractAsWKTPolygons". I personally like this name. Or
>"RasterAsWKTPolygons"...

Probably more something like DumpAsWKTPolygon(s)() (and ST_DumpAsPolygon(s)()). We still have to settle the "s" issue.

Pierre