[mapserver-dev] RFC 94: Shape Smoothing

Stephen Woodbridge woodbri at swoodbridge.com
Sat Mar 30 09:20:10 PDT 2013

On 3/30/2013 11:26 AM, Alan Boudreault wrote:
> Hi devs,
> I'd like to request some review on a pending RFC regarding support for
> shape smoothing.
> Please see http://mapserver.org/development/rfc/ms-rfc-94.html
> It's a first draft, we might have to correct/improve some points.

Overall, it is a very nice RFC and explains the problem well along with 
your proposed solution. Thanks.


You mentioned that there are a lot of pathological cases and ways to 
work around them. I think that the reality will be that in a single file 
we will probably have some of all the bad cases so how can we deal with 
this likely case?

Is there an easy (fast) way to guess what cases we are dealing with? 
Then set the parameters for that case?

For example:

* check if the start and end are the same: likely loops and apply the 
angle case

* compute the average deviation from the smoothing average and ...
* compute num_pnts/length over your window or your window+2 points and ...

Maybe this is covered in the paper you referenced, I did not read it, 
but it seems that if we know some condition will generate bad results, 
the we should be able to also detect or guess that condition is in play 
for a given segment then apply the fix, maybe this is called the 
"auto_adjust" options.

Regardless, good work on this, and identifying the issues is half the 
problem of solving them.

-Steve W

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