[postgis-users] Problems with GeomUnion

[Bill Binko]

On Thu, 7 Apr 2005, Martin Davis wrote:

> The large polygon is invalid.  It has a self-intersection in the lower
> left corner at the boundary with the other polygon.  One of the input
> polygons which formed it must be invalid.
> 
> (See attached screenshot)

Thanks for the quick response!  A couple of questions:

1) What tool did you use to find that?
2) Is there a way to test shapes for validity in PostGIS?  Like an 
isvalid() function?

Thanks
Bill