[postgis-users] Problem with overlay

[Mark Cave-Ayland]

On Sat, 2007-06-30 at 14:05 -0400, Jonathan Aguero wrote:
> Listers
> 
> I got a multilinestringM shape that I loaded into postgis without
> problem (LRS). Then I used the linear referencing functions to create
> the segments and curves tables from the tables (BTW, these linear
> referencing functions rock!!!!). Now, my problem is that when I tried
> to join the information on curves into the segments table using the
> overlay function, it failed to detect several curves. Note that both
> geometries (segments and curves) are generated from the same base
> lines (LRS), therefore all curves should overlay one or more segments.
> I am guessing I encountered a precision problem on GEOS but I wonder
> whether my guess is correct and if there is any solution (maybe
> snaptogrid).  
> 
> Thanks in Advance for your help
> 
> PS:
> 
> OS: Windows XP
> 
> PGSQL: PostgreSQL 8.2.3 on i686-pc-mingw32, compiled by GCC gcc.exe
> (GCC) 3.4.2 (mingw-special)
> 
> Postgis: 1.2
> 
> GEOS: 3.0.0rc4-CAPI-1.3.3
> 
>  
> 
>  
> 
> Jonathan Aguero Valverde
> 
> Research Assistant and Ph.D. Candidate
> 
> Pennsylvania State University
> 
> The Pennsylvania Transportation Institute
> 
> 201 Transportation Research Building
> 
> University Park, PA 16802
> 
> www.personal.psu.edu/jua130


Hi Jonathan,

Not sure about whether I can help you, however we need a concrete test
case to able to determine whether this is a bug or not. Basically an SQL
file containing a couple of tables containing some sample geometries
along with the join you are using would be a great help.


Kind regards,

Mark.

-- 
ILande - Open Source Consultancy
http://www.ilande.co.uk