[Mapserver-users] Display polygon layer as circle layer

[Eric Bridger]

Stefan,
As far as I know there is no simple way to accomplish this.  But I do
think your approach is the way to go, i.e. create a point layer which
corresponds to your polygon layer. But I would create a separate
shapefile. Then you could display the boundaries or the points as
needed. I have done this many times. But the problem is to find an
appropriate centroid for a given polygon.  Perhaps you could find an
existing shapefile of national capitols and use those as your points.

Eric


On Mon, 2003-07-14 at 13:38, Stefan Schwarzer wrote:
> Dear all,
> 
> I have some (polygon) layers containing national statistics (for example 
> GDP or Population Density). They are nicely displayed in five categories, 
> represented by different colors. Now, I would like to place another, 
> geospatial (e.g. land cover, DEM) layer under it. I can change the 
> transparency of the statistical layer, but the result is not very nice. It 
> is too difficult to recognize the correct category, as the two layers are 
> becoming too blurry.
> 
> Now I thought perhaps it would be more meaningful if I would overlay the 
> geospatial/background image with a "circle-layer", instead of a 
> "polygon-layer". The size or the color of the circles would represent then 
> the value of the country. This would leave enough space to see the 
> background image, but one could still recognize the different categories of 
> the statistical layer.
> 
> Is there a simple way to accomplish this? Do I have to create from the 
> polygon shapefile a point shapefile on-the-fly, before then displaying the 
> latter?
> 
> Thanks for any help,
> 
> Stefan
> 
> 
> 
>          _______________________________________
> 
>          Stefan Schwarzer
>          Consultant on GEO
> 
>          UNEP/DEWA/GRID-Geneva
>          Chemin des Anemones 11
>          CH - 1219 Chatelaine
>          Switzerland
> 
>          Tel: (+41) 22.917.83.49
>          Fax: (+41) 22.917.80.29
> 
>          Email: stefan.schwarzer at grid.unep.ch
>          Internet: http://geodata.grid.unep.ch/
>          _______________________________________