Isochrones maps with Mapserver

[Stephen Woodbridge]

R Baud wrote:
> I all,
> I'm searching a way to do some isochrone maps with mapserver. I believe 
> that no capabilities were implemented in mapserver to do that yet. So I 
> suppose use mapserver and my web page only for the request and for 
> drawing the result (am I wrong?). What must be done between, 
> calculations, requests and polygons drawing should be done by another 
> program. Perhaps with PhP & Mapscript or with special CGI routine or 
> perhaps anything else ??
> My datas contain many informations such as speed, vehicles, 
> weight limitations etc... For this development the environment must be 
> able to do database queriing and also spacial queriing (into shape 
> files, etc..)
> I know that a firm created a application with mapserver to do that, but 
> they didn't explain a little how.
> Do someone experienced a little in this subject? Any hint would be very 
> appreciated!

You can do it but it requires you to pre-calculate the data and then use 
mapserver to render it. I have a drive time analysis that displays 
isochrone maps you can see it here http://imaptools.com/demos1/?tab=3

This works by computing the isochrones and writing a shapefile with 
nested overlapping polygons. Each polygon has an attribute that is then 
used as a CLASSITEM in the mapfile to render it, and I use PHP in this 
demo to glue everything together.

There is some prototype support for color ramps being added to mapserver 
that would make it easier to define the isochrone color ramps in the 
mapfile. Do a search on the archives for COLORRAMP should reveal more on 
that.

Hope this helps,
   -Steve W.