Re: Geometric computation software
Re: Geometric computation software
- Subject: Re: Geometric computation software
- From: "Philip D Riggs" <email@hidden>
- Date: Tue, 27 May 2003 15:17:50 -0600
Thanks Brock and Oscar for the help!
The GPC looks like exactly what I wanted.
Brock, if you don't mind me asking, how do you handle floating point
accuracy in
your applications? Also, in the software package I use for map analysis,
a fuzzy tolerance limit is used to help prevent small, sliver polygons that
can
arise. For example, if a vertex is within a specified distance of another
vertex, they
are joined together. Because our map data can often have up to 4 meters
location
error I would like to be able to specify that any 2 vertices within 2 (or
whatever)
meters of each other are joined to form one single vertex. Have you done or
seen anything like this implemented, and would it greatly slow down
processing?
----------------------------------------------------------------------------
----
Philip D. Riggs
GIS Specialist / Laboratory Manager
Environmental Health Advanced Systems Laboratory
Colorado State University
Fort Collins, Colorado
http://ehasl.cvmbs.colostate.edu/
----- Original Message -----
From: "Brock Brandenberg" <email@hidden>
To: <email@hidden>; <email@hidden>
Sent: Monday, May 26, 2003 11:27 AM
Subject: Re: Geometric computation software
>
Hi Philip.
>
>
> Has anybody used a geometric computation toolset for such things as
polygon
>
> intersection, distance between points, and other vector graphics
operations? I
>
> have found a package called Magic Software. Has anybody used this in a
>
> project, and if so how did it go? Was it easy to integrate?
>
>
We use GPC (general polygon clipper) in a Cocoa, rule-based publishing app
>
that positions objects based on their geometry, so GPC is at the heart of
>
the geometry engine that manipulates and calculates intersections for the
>
object shapes. GPC is a tiny C library and is extremely fast and robust.
>
Because it's C and is so small, it was relatively easy to integrate and
use.
>
>
http://www.cs.man.ac.uk/aig/staff/alan/software/
>
>
We have had zero problems with GPC. The only issue we run into is the
usual
>
floating point accuracy issues that are inherent to geometric computation
>
and are no fault of the library.
>
>
Brock Brandenberg
>
>
----- industrial design @ www.bergdesign.com ------
_______________________________________________
cocoa-dev mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/cocoa-dev
Do not post admin requests to the list. They will be ignored.