Hi, I do not believe that the size of BBOX and HEIGHT/WIDTH has any effect at all. The mathematics for finding the coordinates of the selected pixel is always the same. Server does not ever render that image if you are thinking about that.
One thing you would probably know about Geoserver is that I just learned that it is applying a buffer to the coordinates and by default it is three image pixel wide. Otherwise it would be practically impossible to find any points or linear features. You can control that with Geoserver vendor parameter "buffer". -Jukka Rahkonen- Gis Mage wrote: > > Thanks, guys! > > I'm just looking for a way to reduce the length of a request, because > I'm requesting a lot of layers at once. > Layer group is not an option, because the list of the layers is being > formed programatically. > > WFS GetFeature is cool, but I guess it requires proxy - I have to > investigate that. > > So the smaller the BBOX and HEIGHT/WIDTH, the faster a client gets a > response, right? > > > 2011/11/11 Ian Turton <[email protected]>: > > On 11 November 2011 09:07, Rahkonen Jukka > <[email protected]> wrote: > >> Hi, > >> > >> That all comes from WMS standard and it is rather well > written there > http://portal.opengeospatial.org/files/?artifact_id=1081&versi > on=1&format=pdf > >> > >> Logic goes somehow in opposite direction than what you > planning to do. It assumes that user has made a GetMap > request and sees a map on a screen. It is just an image and > does not include any information about georeferencing. If use > is clicking on a map the client software can only record > which pixel was clicked. However, the georeferencing can be > computed on the WMS server side if the WMS GetMap request > with BBOX and image size is known. > >> > >> LAYERS just need to be in the request because standard > says so but QUERY_LAYERS is the one used for selecting layers > to be queried. They do not need to be the same. > > > > LAYERS is there because in theory you can just change the > request from > > getmap to getfeatureinfo and concatenate the click location > and query > > layer and send it back. This meant that back in the early > days before > > JavaScript became popular you could create a WMS client > with some cgi > > shell scripts and a submit button in ah HTML form. > > > >> > >> For creating GetFeatureInfo requests from a scratch you > will need to do some calculation. The the centre point, > decide some image size in WIDTH and HEIGHT and compute BBOX > according to those. > > > > If you find that you are having to do that sort of calculation then > > you should probably be using a WFS getFeature request > instead of a WMS > > getFeatureInfo. > > > > Ian > > > ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Geoserver-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geoserver-users
