Hi Ric,
AFAIK, there is no way with mapnik (currently) to dynamically add
points to a map.
I think what you are after is the correct way to read in a point
datasource of gps points and symbolize them.
I'd use gdal or gpsbabel to convert your data to gpx then shp.
Then I would modify one of the basic mapnik xml tutorial stylesheets
to use a PointSymbolizer, like:
<Style name="pnts">
<Rule>
<PointSymbolizer file = "symbols/your_graphic.png" type="png"
width="10" height="10" />
</Rule>
</Style>
<Layer name="points" status="on">
<StyleName>pnts</StyleName>
<Datasource>
<Parameter name="type">shape</Parameter>
<Parameter name="file">shapefile_of_gps_points</Parameter>
</Datasource>
</Layer>
You'll need to create and link to a graphic you want to use for the
point symbol.
Tutorials using xml can be found here: http://trac.mapnik.org/
But mapnik.org is currently down so you can also fetch them from here:
http://code.google.com/p/mapnik-utils/source/browse/trunk/tutorials/
Hope that helps,
Dane
On Aug 7, 2008, at 2:15 AM, Ric S wrote:
> Hi folks,
>
> I have successfully setup mapnik. Generating a map already works.
> Now I would like to draw gps points into the map, I was searching the
> net for a few hours to get some info, unfortunately
> I still have now clue yet how this can be done with mapnik.
> I assume I have to create a layer and add points to it. I could not
> find
> an example how to draw points.
>
> I would like to set gps points in my map. Could you please show me
> how to
> add a single gps point to this map/layer. The code from generate_image
> which I used:
> ...
> z = 10
> imgx = 100 * z
> imgy = 100 * z
>
> m = Map(imgx,imgy)
> load_map(m,mapfile)
> prj = Projection("+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0
> +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m [EMAIL PROTECTED] +no_defs
> +over")
> c0 = prj.forward(Coord(ll[0],ll[1]))
> c1 = prj.forward(Coord(ll[2],ll[3]))
> bbox = Envelope(c0.x,c0.y,c1.x,c1.y)
> m.zoom_to_box(bbox)
> im = Image(imgx,imgy)
> render(m, im)
> view = im.view(0,0,imgx,imgy) # x,y,width,height
> view.save(map_uri,'png')
> ...
>
> Thanks in advance, Richard
>
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