ALRIGHT !! It was a noob mistake indeed, I did not specify UNITS in the MAP object. In fact I thought Mapserver could know it from the shapefile.
Thank you very much, it works fine now :) Faldor 2008/5/29 Fawcett, David <[EMAIL PROTECTED]>: > MapServer should do the conversion on the fly, my point was just that > MapServer needs to know what SRS (and units) that the data is in, so it can > make the translation. > > Can you post the text of your map file? > > David. > > -----Original Message----- > *From:* Pierre-Benoit Besse [mailto:[EMAIL PROTECTED] > *Sent:* Thursday, May 29, 2008 2:51 AM > *To:* Fawcett, David > *Cc:* [email protected] > *Subject:* Re: [MAPSERVER-USERS] Displaying population density with > Mapserver > > Hi David, > > I tried WGS84 yesterday after a little research on projection, but it > didn't change anything. > I tried re-generating the shapefile with WGS84 projection but it's still > the same. > In fact, my data comes from GPW v3 ( > http://sedac.ciesin.columbia.edu/gpw/global.jsp) but I didn't find any > clue on the projection used, I suppose there is none as you say. > > When you speak about translating ground units, do you mean I have to > translate my shapefile from degrees to, say, kilometers before I can use > SIZEUNITS kilometers ? I thought it could be done dynamically by MapServer. > I found a tutorial about this, I will try it anyway (assuming my data is > WGS84) and give you the outcome :) > > I attached my mapfile this time, just in case I made a noob mistake > somewhere... > > thank you very much ! > > Faldor > > 2008/5/28 Fawcett, David <[EMAIL PROTECTED]>: > >> Faldor, >> >> When you have point coordinates stored in a text file, there really is >> no way to encode/attach the projection definition. Even if you could, >> it doesn't sound like you really know what spatial reference system >> (SRS) or projection that it is in. The key to projecting to another SRS >> or translating ground units to another measure (from degrees to meters) >> is knowing what the current SRS of the data is. >> >> Since your data is worldwide and it is unprojected (lat/lon), a good >> first guess would be to assume that it is unprojected with using the >> WGS84. >> >> Try defining your layer projection by including this block in your layer >> definition. >> >> PROJECTION >> "init=epsg:4326" >> END >> >> David. >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> Pierre-Benoit Besse >> Sent: Wednesday, May 28, 2008 4:11 AM >> To: Fawcett, David >> Cc: [email protected] >> Subject: Re: [MAPSERVER-USERS] Displaying population density with >> Mapserver >> >> >> Well, I confess, I'm new to GIS applications and I do not know a lot >> about projections. >> I understand I have to tell MapServer what is the projection of each >> layer I use in the mapfile, but using ogrinfo on my shapefiles tells me >> that : >> >> Layer name: pop_density >> Geometry: Point >> Feature Count: 249937 >> Extent: (-180.000000, -56.000000) - (179.750000, 83.500000) >> Layer SRS WKT: >> (unknown) >> latitude: Real (24.15) >> longitude: Real (24.15) >> densite: Real (24.15) >> >> I generated this shapefile from a CSV file with 3 columns : latitude, >> longitude, density_value. >> Did I have to define a projection then ? How do I do that ? >> >> Best regards, >> >> Faldor >> >> >> 2008/5/27 Fawcett, David <[EMAIL PROTECTED]>: >> >> Have you defined an output projection for your map and input projections >> for each of your layers? It is likely that MapServer needs to know what >> the input projection/SRS is before it can translate to different units. >> >> David. >> -----Original Message----- >> From: Pierre-Benoit Besse [mailto:[EMAIL PROTECTED] >> Sent: Tuesday, May 27, 2008 11:26 AM >> To: Fawcett, David >> Cc: Ritesh Ambastha; [email protected] >> Subject: Re: [MAPSERVER-USERS] Displaying population density with >> Mapserver >> >> >> Ha, well, I prefer that :) I would need a lot of layer definitions to >> obtain something ok... >> >> But I just tried the "ground units" stuff, I tried with a 50 kilometers >> wide square and it drew squares the size of ASIA !! oO >> I had to define a 1 feet wide square to obtain something more or less >> ok... >> Does anybody know why ? >> >> Aside from that It seems to work, thank you ! >> >> I will try the scalesymbol stuff tomorrow. >> >> Regards >> >> >> >> 2008/5/27 Fawcett, David <[EMAIL PROTECTED]>: >> >> Before you create lots of different layers to simulate symbol scaling, >> you may want to try something else. It has been a long time since I >> have played with scaled symbols, but give it a try. >> >> You should be able to scale the symbols by setting a SYMBOLSCALE in the >> LAYER object. This is the scale at which you want the symbol to appear >> at the SIZE stated in the map file. >> >> You may want to modify STYLE MAXSIZE if you think that you will want >> your symbols to be larger than 50 pixels. >> >> Another completely different approach that just came to my mind would be >> to use ground units (e.g. meters) to set the size of your symbol. To do >> this, set LAYER SIZEUNITS to meters. Calculate the size of a symbol in >> meters on the ground that will touch adjacent symbols, or give you the >> desired amount of space between the symbols. That way, the symbols >> should scale consistently. >> >> David. >> >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> >> [mailto:[EMAIL PROTECTED] On Behalf Of Ritesh >> Ambastha >> Sent: Tuesday, May 27, 2008 10:16 AM >> To: [email protected] >> Subject: Re: [MAPSERVER-USERS] Displaying population density with >> Mapserver >> >> >> >> Dear Faldor, >> >> Robert is absolutely right. You will have to make different LAYERS for >> the same POINT layer. But, define MAX/MINSCALE for each Layer. Change >> STYLE -> SIZE values in each of the layer. You are done !! >> >> Cheers ! >> Ambastha >> >> >> Faldor wrote: >> > >> > Yes, but I need them to adapt for different extents. >> > >> > For example, When I zoom out enough to see the world, I need them 1 >> > pixel wide (it's ugly otherwise), but when I zoom in I will need then >> > 2 or 5 or even 30 pixels wide to cover all space. >> > >> > 2008/5/27 Ritesh Ambastha <[EMAIL PROTECTED]>: >> > >> >> >> >> Dear Faldor, >> >> >> >> <snip>What I need is to have the points grow to cover all space >> >> available when I zoom in.</snip> >> >> >> >> Do you mean that the size of points should grow? It can be done >> >> easily by setting proper SIZE in the STYLE tag. >> >> >> >> >> >> Regards, >> >> Ambastha >> >> >> >> >> >> >> >> Faldor wrote: >> >> > >> >> > Hi, >> >> > >> >> > Sorry for my first empty message. >> >> > >> >> > My problem is, I need to display population density with Mapserver. >> >> >> > The data comes from GPWv3 and has a resolution of 15'. I converted >> >> > it to a POINT Shapefile using ogr2ogr. >> >> > >> >> > At first when I display it on a world map it shows nicely. But when >> >> >> > I >> >> zoom >> >> > in it begins to show separated points for each value in the >> >> > shapefile. What I need is to have the points grow to cover all >> >> > space available >> >> when >> >> I >> >> > zoom in. >> >> > >> >> > Is there any mean to do it with Mapserver ? I did not find it in >> >> > the mapfile reference. >> >> > >> >> > I don't know if I explained it well (I'm not english speaking). If >> >> > you >> >> do >> >> > not understand something, please ask. >> >> > >> >> > Cordialy, >> >> > >> >> > Faldor >> >> > >> >> > >> >> > >> >> >> >> -- >> >> View this message in context: >> >> http://www.nabble.com/Displaying-population-density-with-Mapserver-tp >> >> 17492210p17492387.html >> >> Sent from the Mapserver - User mailing list archive at Nabble.com. >> >> >> >> _______________________________________________ >> >> mapserver-users mailing list >> >> [email protected] >> >> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> >> >> > >> > _______________________________________________ >> > mapserver-users mailing list >> > [email protected] >> > http://lists.osgeo.org/mailman/listinfo/mapserver-users >> > >> > >> >> -- >> View this message in context: >> http://www.nabble.com/Displaying-population-density-with-Mapserver-tp174 >> >> 92210p17492783.html >> >> Sent from the Mapserver - User mailing list archive at Nabble.com. >> >> _______________________________________________ >> mapserver-users mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> _______________________________________________ >> mapserver-users mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> > >
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