[mapserver-users] abutters lists....

[woodbri at swoodbridge.com]

The buffering algorithm is tricky, but an interesting problem. 
Growing the vectors from the centriod only works for convex polygons, 
it will fail for concave polygons like:

      +---------+       +---------+
       |          |        |          |
       |          +------+          |
       |                              |
       +----------------------------+

The right way to do this, I think, is to walk around the polygon and 
construct offsets, then interest the offsets and re-chain the 
segments into a new polygon, you also have to eliminate loops on the 
new polygon caused by the fact that the offset can eliminate some 
features from the new polygon. For example with a large enough offset 
the notch in the above would be eliminated from the topology of the 
new offset polygon changing it from 6 vertices to 4 vertices.

-Steve W.

On 19 Nov 2002 at 15:14, Steve Lime wrote:

> Ed: Hey, it was worth a shot. Everything is square here.
> 
> I see two needs. One for a buffering algorithm (I've looked and
> haven't found much of anything.)
> 
> The other is for a process to compute the distance between arbitrary
> shapes. The point to vector code already exists.
> 
> Anyone want to help?
> 
> Steve
> 
> Stephen Lime
> Data & Applications Manager
> 
> Minnesota DNR
> 500 Lafayette Road
> St. Paul, MN 55155
> 651-297-2937
> 
> >>> kevinflanders at rcn.com 11/19/02 11:40AM >>>
> It's great to see so many reactions to this abutters list need....and
> buffering seems to be the way to go.  I totally agree with Ed that
> "close" is not going to be enough....especially for legal abutter's
> lists that are subject to questions.
> 
> How would we go about addressing the code to open the door to this
> functionality?
> 
> 
> 
> Kevin
> 
> 
>