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In my practice I use a lot WMS and WFS in Geoserver. I have not found a document describing the concept of a bounding box(bbox). ArcGIS has map extent properties to identify map boundary. Google Map/Bing map has getbound() method to identify the map view. However, when defines a bounding box in WMS or WFS, it seems to involve projections parameters and map view extent. The parameters in an HTTP GetMap request looks confusing to me since if I use different projection systems the units in the bounding box varies significantly, and the incorrect setup of bbox would cause rendering fail So, could anyone point me to the document explaining the bbox?
Thank you!

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up vote 7 down vote accepted

Bounding Boxes are usually a request to the 'geo' server in the projection you are using or requesting.

bbox: The bounding box is automatically determined by taking the union of the bounds of the specified layers. In essence, it determines the extent of the map. By default, if you do not specify bbox, it will show you everything. If you have one layer of Los Angeles, and another of New York, it show you most of the United States. The bounding box, automatically set or specified, also determines the aspect ratio of the map. If you only specify one of width or height, the other will be determined based on the aspect ratio of the bounding box.

.. Warning:: If you specify height, width and bounding box there are zero degrees of freedom, and if the aspect ratios do not match your image will be warped.

Example for WGS84 Lat/Lng:

http://localhost:8080/geoserver/wms?service=WMS&request=GetMap&version=1.1.1&format=application/openlayers&width=800&height=600&srs=EPSG:4326&layers=topp:states&styles=population&bbox=-180,0,0,90

http://docs.geoserver.org/2.1.0/user/_sources/tutorials/wmsreflector.txt

INSIDE Geoserver you can set the maximum bounding box in either Native SRS or the Projection for the output SRS (named Declared SRS in Geoserver): The bounding box determines the extent of a layer. The Native Bounding Box are the bounds of the data projected in the Native SRS. You can generate these bounds by clicking the Compute from data link. The Lat/Long Bounding Box computes the bounds based on the standard lat/long. These bounds can be generated by clicking the Compute from native bounds link.

Bounding Box Settings in Geoserver

More information: http://docs.geoserver.org/latest/en/user/webadmin/data/layers.html#bounding-boxes

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So if the projection is EPSG:900913, the bbox should reflect the boundary of this projected coordinate system right? –  Seen Jun 7 '11 at 14:53
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@seen you are correct –  Mapperz Jun 7 '11 at 16:42
    
Thank you very much! –  Seen Jun 7 '11 at 17:15
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