[mapserver-users] RE: Dynamically draw different sized ellipses on map

[Fawcett, David (MPCA)]

I think that others will be able to answer this far better than I can.  There are likely many ways to do this, it might help if you gave us a little bit more info about what you are doing.  

It sounds like the coordinates and area of the polys are determined on the client side and then need to be passed to the server for rendering? 

I do see an example in the comments to Matt's post where someone uses MapServer MapScript (in place of a CGI call) to build the data and add it to a dynamic map.  It looks like they are writing out a shapefile and then using the shapefile as the source for a layer.  I wonder if this might lead to unexpected results unless you can guarantee unique shapefile names for each map request.  

I believe that if you went the mapscript route, you could just build the poly features dynamically and use them in your layer without writing the features out to disk.  

I think that optimization will depend on your requirements.  If a user starts a session, a data set is built, and then the client requests thousands of tiles based on those same features, there will likely be value in writing the features out to a shapefile or database.  On the other hand, if the user hits a page and only one static map will be drawn based on the new unique features, there is likely no need to serialize the features.

David.


-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of stoli
Sent: Wednesday, September 08, 2010 11:11 AM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] RE: Dynamically draw different sized ellipses on map


Thanks David.

Those are excellent references. I hadn't seen Matt Perry's site before. The
Tissot Indicatrix certainly shows the distortion that I need to deal with
due to map projection. I think I can work out the geometry of the ellipses.

Assuming that the application needs to be capable of rendering up to 100 of
these ellipses at varying locations at any given time, would you say the
most efficient way to do this is to program the app to dynamically build a
shape file and add it as a map layer each time a user requests the page, or
create them as symbols (in which case I think I would need a different layer
for each ellipse). I suppose I might run into URL length limits with the
latter. Is there another possibility that I am missing?
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