Hi Daniel,
you are right, SIZE is equivalent to WIDTH/HEIGHT in WMS. And EXTENT is
equivalent to BBOX.
Are you able to send us some screendumps of what you are experiencing?
Or put them on a website and send the links?
Best regards,
Bart
Daniel Goetz wrote:
Hi Bart,
thank you again for your help.
I am sorry, but I think because of my limited skills in writing in english you
have misunderstood what I wanted to say. Sorry for that.
I meant in my last email that the EXTENT in a mode=browse ("normal" mapserver CGI request) is the
equivalent to the BBOX-values in the WMS-GetMap-request. And that SIZE in "normal" mapserver
request is equivalent to WIDTH/HEIGHT in WMS-GetMap-requests. Am I right? And the EXTENT-values and the
BBOX-values did not alter; neither in the WMS-request nor in the "normal" mode=browse CGI
mapserver-request. Same with SIZE and WIDTH/HEIGHT. And nevertheless these values did not alter in the two
different requests, the returened reprojected maps differ (stretching).
I think the stretching behaviour (non square pixels) is specific to WMS
and won't happen in Mapserver CGI mode.
It is the map of the "normal" mode=browse mapserver-request that seems to be
stretched compared to the not reprojected map. The reprojected map of the
WMS-GetMap-request looks similar/equal to the not reprojected map.
But isn't it quiet normal that reprocetion causes some kind of stretching and
distortion? Please correct me if I am wrong.
So thank you for your reply. And sorry for my bad english/description of my
problems. Thank you for furhter support in advance.
regards
Daniel
-------- Original-Nachricht --------
Datum: Fri, 28 Jul 2006 10:52:39 +0200
Von: "Bart van den Eijnden (OSGIS)" <[EMAIL PROTECTED]>
An: Daniel Goetz <[EMAIL PROTECTED]>
Betreff: Re: [UMN_MAPSERVER-USERS] WMS and SRS
Hi Daniel,
I think the stretching behaviour (non square pixels) is specific to WMS
and won't happen in Mapserver CGI mode.
For WMS, the SIZE and EXTENT of the MAP file don't matter, since they
are specified in the request.
The easiest is to test with a square image. So eg 400 x 400 pixels.
Then make sure that MAXX-MINX equals MAXY-MINY (BBOX=MINX,MINY,MAXX,MAXY).
Best regards,
Bart
Daniel Goetz wrote:
Hi Bart,
thank you for your reply.
But the extent in the mapfile is the same as the BBOX-values in the
WMS-request. And the SIZE in the MAP-object of the mapfile is the same as in
WIDTH+HEIGHT in the WMS-request. And nevertheless the two "reprojected" maps
differ in appearance (distortion).
But you are right. I should check that the BBOX and the
WIDTH/HEIGHT-values have the same proportion. Do I also have to check wheter
SIZE and EXTENT
in the MAP-object have the same proportions as well? And how can I measure
the distance between the vertices of my EXTENT and the distance between
the vertices of my BBOX? Any suggestion?
Thank you for your help and hopefully your further ideas. Thank you.
regards
Daniel
-------- Original-Nachricht --------
Datum: Fri, 28 Jul 2006 10:26:38 +0200
Von: "Bart van den Eijnden (OSGIS)" <[EMAIL PROTECTED]>
An: Daniel Goetz <[EMAIL PROTECTED]>
Betreff: Re: [UMN_MAPSERVER-USERS] WMS and SRS
Hi Daniel,
please remember that if the ratio of your bbox and the ratio of your
width versus height in pixels, differs, the map will be stretched. That
could explain some of the behaviour. You need to make sure that the
values in your WMS request have the same ratio. I don't know if this is
the problem, but it could be a cause.
Proj.4 has a utility to reproject. The proj utilities also come with
MS4W. See also:
http://proj.maptools.org/man_cs2cs.html
Best regards,
Bart
Daniel Goetz wrote:
Hi,
thank you Frank, Trond and Ed for your help. I tried to use reporjected
coordinates as BBOX-values in my "new" WMS-GetMap-request
(SRS=WPSG:4326)
and it works now. I got the new reprojected coordinates out of the
GetCapabilities document (I took them out of the LatLonBoundingBox
paragraph in the
GetCapabilities document):
<Layer queryable="1" opaque="0" cascaded="0">
<Name>VIEW_RWG_TBS</Name>
<Title>RWG_TM_NR</Title>
<SRS>EPSG:31468</SRS>
<SRS>EPSG:4326</SRS>
<LatLonBoundingBox minx="10.9905" miny="49.3319" maxx="11.2852"
maxy="49.5441" />
<BoundingBox SRS="EPSG:31468"
minx="4.42695e+006" miny="5.46647e+006"
maxx="4.44806e+006" maxy="5.48982e+006" />
<Style>
<Name>default</Name>
<Title>default</Title>
<LegendURL width="20" height="10">
<Format>image/png</Format>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink";
xlink:type="simple"
xlink:href="http://10.65.112.50/cgi-bin/mapserv.exe?map=/ms4w/apache/htdocs/WMS/WMS_BRWK.map&version=1.1.1&service=WMS&request=GetLegendGraphic&layer=VIEW_RWG_TBS&format=image/png"/>
</LegendURL>
</Style>
</Layer>
But I have two further questions:
When I do a WMS-GetMap-request in the "new" SRS (EPSG:4326) the map
maserver sends back does not vary form the map mapserver generates when
sending
a GetMap-request in the "original" SRS (EPSG:31468). I mean there is no
deformation/distortion noticeable. But when I do a "normal" mapserver
mode=browse-request in my simple pan and zoom template and tell
mapserver to
reproject the data in EPSG:4326 (I do that by putting the
PROJECTION-object in
the MAP-object of the .map-file to "init=epsg:4326" while the
PROJECTION-objects in the LAYER-objects are still in the "origninal"
"init=epsg:31468"
projection. Of course I change the EXTENT-parameters in the .map-file
too. Am
I doing right?) the returned map looks different >from the map
genereated
using the "original" projection. I mean that the reprojected map using
mode=browse looks deformed/distorted compared to the "original" not
reprojected
map.
The question is now: Why do the two maps (the reprojected one I get
from
the WMS-GetMap-request and the reprojected map I get by a mode=browse
request) differ in their appearence (distortion) although I tell
mapserver in
both cases to reproject the map to "epsg:4326"?
The secoond question is: As mentioned I got the "new" reprojeted
coordinates for BBOX-values out of the GetCapabilities document. But is
there a
program that could do coordinate transformation for me, so that I am
able to
transform "epsg:31468" coordinates to "epsg:4326" coordinates?
OK, that's it. Thak you again for your helpful hints. And would be very
nice of you if you could help me further on with my problems/questions
elucidated in this email. Thank you so much.
regards
Daniel
-------- Original-Nachricht --------
Datum: Thu, 27 Jul 2006 09:22:21 -0400
Von: Ed McNierney <[EMAIL PROTECTED]>
An: [email protected]
Betreff: Re: [UMN_MAPSERVER-USERS] WMS and SRS
Daniel -
I think Frank's theory is likely to be correct, and that there is a
problem with the BBOX coordinates used in your new request. It sounds
like the
changes you made are fine, although I think it is not necessary to add
all
supported SRS systems to the metadata for each layer - just the
MAP-level
metadata should be all you need to do.
Can you post the SRS= and BBOX= parameters you are using in your
original
epsg:31468 request and in the new epsg:4326 requests?
- Ed
Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA 01863
[EMAIL PROTECTED]
(978) 251-4242
-----Original Message-----
From: UMN MapServer Users List [mailto:[EMAIL PROTECTED]
On
Behalf Of Daniel Goetz
Sent: Thursday, July 27, 2006 3:05 AM
To: [email protected]
Subject: [UMN_MAPSERVER-USERS] WMS and SRS
Hi coummunity,
I built up a littel WMS-server with umn-mapserver (local installation;
ms4w 2.1). The "original" projection of the single Layers is alway
epsg:31468
(these are cartesian Gauß-Krüger-coordiantes). So I set the
PORJECTION-object of each LAYER and in the MAP-object to
"init=epsg:31468". In the
METADATA of the MAP-object as well as in the single LAYER-objects I
defined
"wms_srs" as "EPSG:31468" as well. For testing purpose I did some
WMS-GetMap-Requests with "SRS=EPSG:31468" and everything went fine.
But now I want to make my WMS-service more interchangeable, so I want
to
define some more SRSs in that the WMS should be able to be displayed.
I
want
to make it possible to "transform" (don't know the exact word in
english)
the WMS from its original Projection to another SRS (e.g. WGS 84;
EPSG:4326). In my opinion this should be possible by adding another
epsg-code to the
METADATA. So my METADATA (both in the MAP and in the LAYERs-objects)
look
like this: "wms_srs" "EPSG:31468 EPSG:4326".
But now every time I change the SRS block in my WMS-GetMap-request
from
"SRS=EPSG:31468" to "SRS=EPSG:4326" mapserver returns a blank image. I
even
tried to set the BBOX to latlon-coordinates when using "SRS=EPSG:4326"
but
even this failed. I also testes other SRSs (both geographic ones and
real
projections) but with no success.
Could anybody please give me some help or hints what to do and what
went
wrong and why did this happen? I would be very glad and thankful.
Thank
you
so much.
regards
Daniel
--
Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer
--
Bart van den Eijnden
OSGIS, Open Source GIS
http://www.osgis.nl
--
Bart van den Eijnden
OSGIS, Open Source GIS
http://www.osgis.nl
--
Bart van den Eijnden
OSGIS, Open Source GIS
http://www.osgis.nl
