[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? -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Dynamically-draw-different-sized-ellipses-on-map-tp5508425p5511294.html Sent from the Mapserver - User mailing list archive at Nabble.com. ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
[mapserver-users] RE: Dynamically draw different sized ellipses on map
To better understand what I am doing, consider this as an example (perhaps not very realistic, but close enough): Let’s assume you have a site that allows the user to analyze cell phone coverage. Your database has the location of all the towers. Each tower contains various antenna types, each antenna type with a different range. Occasionally, new towers are added to the database, old towers are removed, and antenna types are changed. The user selects the antenna type, submits the request to the server, and the server generates the ellipses that represent each antenna’s coverage. Those ellipses are overlaid on the map and the image is returned to the user. The map image processing is all done server side via cgi requests. Sounds like the best way to do this might be to write out a unique shapefile for each user session. Certain user inputs (like a change in antenna type) will require their shapefile to be updated (rewritten), while other inputs (like zooming, panning, etc.) will not. Thanks again. If anyone knows of a better way to accomplish this, I'm all ears. -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Dynamically-draw-different-sized-ellipses-on-map-tp5508425p5514639.html Sent from the Mapserver - User mailing list archive at Nabble.com. ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
RE: [mapserver-users] RE: Dynamically draw different sized ellipses on map
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-boun...@lists.osgeo.org [mailto:mapserver-users-boun...@lists.osgeo.org] On Behalf Of stoli Sent: Wednesday, September 08, 2010 11:11 AM To: mapserver-users@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? -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Dynamically-draw-different-sized-ellipses-on-map-tp5508425p5511294.html Sent from the Mapserver - User mailing list archive at Nabble.com. ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] RE: Dynamically draw different sized ellipses on map
On Sep 9, 2010, at 4:26 PM, ext stoli wrote: > > > To better understand what I am doing, consider this as an example (perhaps > not very realistic, but close enough): > > Let’s assume you have a site that allows the user to analyze cell phone > coverage. Your database has the location of all the towers. Each tower > contains various antenna types, each antenna type with a different range. > Occasionally, new towers are added to the database, old towers are removed, > and antenna types are changed. The user selects the antenna type, submits > the request to the server, and the server generates the ellipses that > represent each antenna’s coverage. Those ellipses are overlaid on the map > and the image is returned to the user. > > The map image processing is all done server side via cgi requests. Sounds > like the best way to do this might be to write out a unique shapefile for > each user session. Certain user inputs (like a change in antenna type) will > require their shapefile to be updated (rewritten), while other inputs (like > zooming, panning, etc.) will not. If you can generate the features on the server side, you don't need a shapefile, I don't think. Just transform the data into GeoJSON features, and deliver them to the client. The client will maintain these features until they close their page/navigate away. I have been limited on internet access, so I have missed some earlier emails, but if you are just generating shapes on the server, loading them in the map is just as simple as turning them into vector features that you can read and reading them in the client. -- Chris ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
