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: mapserver-users@lists.osgeo.org > 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; mapserver-users@lists.osgeo.org > 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: mapserver-users@lists.osgeo.org > 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 > >> 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 > > > > > > -- > 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 > 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 >
test.map
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