Hi Philippe, I'd agree it seems strange this isn't consistent. There is a lot of code in the MapServer codebase to handle data crossing the antemeridian, so I guess there is an oversight somewhere (and fixing it is likely to be tricky). I think this should be added as an issue, with the examples you provided.
Seth -- web:https://geographika.net & https://mapserverstudio.net mastodon: @[email protected] On Fri, Sep 19, 2025, at 4:13 PM, Philippe Ghesquiere via MapServer-users wrote: > Dear all, > > I noticed a weird behaviour with a WMS request based on EPSG:4326, when the > BBOX exeeds the [-180 ; +180] longitude intervalle. > We bump into this problem when we try to display images over the antimeridian > line. > > I could observe this problem with the "MapServer Demonstration Server". > > *_Observed _*Mapserver response is not consistent whether the BBOX overlaps eastward or westward : > 1) Westward > BBOX=-90,-200,90,100 > The image is clipped on both east and west sides, that is in the [-180° ; > +100°] longitude intervalle. > On the west side, pixels in the [-200° ; -180°] longitude intervalle are > transparent. > > The complete request URL is : > https://demo.mapserver.org/cgi-bin/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=-90,-200,90,100&CRS=EPSG:4326&WIDTH=953&HEIGHT=480&LAYERS=bluemarble&STYLES=&FORMAT=image/png&TRANSPARENT=true&STYLES= > > 2) Eastward > BBOX=-90,-100,90,200 > The image is clipped on the west side, which is OK. > On the east side, pixels in the [+180°; +200°] longitude intervalle are not > correct. > > The complete request URL is : > https://demo.mapserver.org/cgi-bin/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=-90,-100,90,200&CRS=EPSG:4326&WIDTH=953&HEIGHT=480&LAYERS=bluemarble&STYLES=&FORMAT=image/png&TRANSPARENT=true&STYLES= > > > *_Expected _*At least, I would expect to have the same behaviour on both sides of the antimeridian. > > Furthermore, couldn't we get the "repeated world" on the [-200° ; -180°] > (respectively [+180° ; +200°]) longitude intervalle ? > > Thanks for your help > Philippe > The information in this e-mail is confidential. The contents may not be > disclosed or used by anyone other than the addressee. Access to this e-mail > by anyone else is unauthorised. > If you are not the intended recipient, please notify Airbus immediately and > delete this e-mail. > Airbus cannot accept any responsibility for the accuracy or completeness of > this e-mail as it has been sent over public networks. If you have any > concerns over the content of this message or its Accuracy or Integrity, > please contact Airbus immediately. > All outgoing e-mails from Airbus are checked using regularly updated virus > scanning software but you should take whatever measures you deem to be > appropriate to ensure that this message and any attachments are virus free. > _______________________________________________ > MapServer-users mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/mapserver-users >
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