[postgis-users] meaning of distance for unprojected data?

[Stephen Woodbridge]

It works fine if you know what you are getting back. The distance is 
calculated using cartesian distance math with the values being in 
degrees. So you are getting back something like the chordal distance 
between points in degrees. It is probably fine for small distances as 
long as you remember what you are getting or only need an approximation, 
but you might get better results with distance_sphere()

-Steve W.

Duana Stanley wrote:
> When I have unprojected data (SRID = -1) I can still perform the spatial
> query distance() on two geoms even though the documentation for the
> distance() function says cartesian distance using projected units.
> 
> Why does it not produce an error when I ask for the distance between two
> geoms with SRID = -1?  Is there a default GCS used when data is
> unprojected?
> 
> Thanks
> Duana.
> 
> 
> 
>