Discussion :

[dragoncino]

Hello,
I'm sorry I cannot write in french, so I hope someone can reply in english.
I have been requested from a french company to develop a Silverlight program that should get maps from the IGN WMS service with these requirements:

- PGN format (with transparency);
- given size (900 x 700 usually);
- possibly in spherical mercator projection (or anyway compatible with Google Maps), but this is an issue I could manage otherwise.

I succeded in getting the token for atuthentication (using http://jeton-api.ign.fr/getToken?key=XXX), and I managed to get some 256x256 tiles in JPG from the WMS-C service, but this is not what I need, and I usually get messages like "HTTP/1.1 400 Mauvaise Requjte".
I'm not able to find examples of using the WMS service in the way I need. Can someone point me to some more documentation, or samples in C#, Java, VB, Delphi or whatelse?

Merci an avance.

[dgrichard]

Hello,
I'm sorry I cannot write in french, so I hope someone can reply in english.

Ok, let's gite it try

I have been requested from a french company to develop a Silverlight program that should get maps from the IGN WMS service with these requirements:

- PGN format (with transparency);
- given size (900 x 700 usually);
- possibly in spherical mercator projection (or anyway compatible with Google Maps), but this is an issue I could manage otherwise.

* there are layers served in png and layers in jpeg (See . service capabilities) ...

* all layers are served through WMS-C : 256x256 images (See this explanations) ...

* that's the key point
+ either you only the fly reproject : for instance a mapserver between the Geoportal's WMS-C and your application : it works but needs power
+ either you consider that both projections are cylindrical and on the same (almost) datum : you then strech the height of each tile for overlaying WMS-C tiles to get them in web mercator

I succeded in getting the token for atuthentication (using http://jeton-api.ign.fr/getToken?key=XXX), and I managed to get some 256x256 tiles in JPG from the WMS-C service, but this is not what I need, and I usually get messages like "HTTP/1.1 400 Mauvaise Requjte".

This means : Bad request (either BBOX is wrong, or SRS is not the right one, or your request is out of service's bounds

I'm not able to find examples of using the WMS service in the way I need. Can someone point me to some more documentation, or samples in C#, Java, VB, Delphi or whatelse

With the above links and advices, you will be on the track

[dragoncino]

Ok, let's gite it try



* there are layers served in png and layers in jpeg (See . service capabilities) ...

* all layers are served through WMS-C : 256x256 images (See this explanations) ...

* that's the key point
+ either you only the fly reproject : for instance a mapserver between the Geoportal's WMS-C and your application : it works but needs power
+ either you consider that both projections are cylindrical and on the same (almost) datum : you then strech the height of each tile for overlaying WMS-C tiles to get them in web mercator



This means : Bad request (either BBOX is wrong, or SRS is not the right one, or your request is out of service's bounds



With the above links and advices, you will be on the track

Merci beacoup, it works!
Thank to you, I was able to make a primitive TileSource derivative for using in Silverlight Bing Maps Control. Now I should convert x,y,zoomlevel values in a BBOX. Any hint?

[dgrichard]

Merci beacoup, it works!
Thank to you, I was able to make a primitive TileSource derivative for using in Silverlight Bing Maps Control. Now I should convert x,y,zoomlevel values in a BBOX. Any hint?

I don't catch your point, but I am trying to explain how the WMS-C works :

1/ all in all, a WMS-C client is 100% a WMS client ...
2/ ... except :
a) the trailing TILED=true parameter and value ;
b) the BBOX parameter must be a tile BBOX : the explanation is in this page (below
Computation of the extent (lower left and upper right corners) chapter's header)
c) because it is a tiles service, each level of the tiles' pyramid corresponds to a resolution (see over there for resolutions). For each resolution, you have the equivalent scale;
d) finally, in the same page (below
Examples of WMS-C requests for getting tiles covering the (2°28'44.1", 48°48'20.3") location : you will find how to compute the BBOX for a given location and scale