WCS and Reprojection with TileItem

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WCS and Reprojection with TileItem

Jérôme Martin-4
Hi,

I'm using mapserv like WMS and now, I would like use the WCS service to get DEM, from DTED files.

To do this, i used gdaltindex software to create a shapefile to have only one entry on my mapfile with the "TILEITEM" keyword.

I precise my dted file are LatLon, in EPSG:4326.

So when i did a request Getmap from the server, i had the result i wanted for, in lat-lon.
But my problem was when i tried to send the request, but with CRS=epsg:32631 (UTM Zone N31) by example (BBOX in 32631 too), nothing work and the server send me a file with the good boundingbox envelloppe, but with no data, only 0.

When I tried to do a resquest with CRS=epsg:4326 (BBOX in 4326)  and RESPONSE_CRS=epsg:32631, i have the same empty 0 file, and the server doesn't warn me any error. Just a file with 0m data elevation.

I'm really surprised, because the OGC documents about the WCS Service tell the response_crs can be used to have a reprojection, and the how-to user case from the mapserver website tell this option can be used.

So when i try to put only one file with the DATA keyword, i was really surprised to see a request in another crs gave me the good reprojection and the right results, so the reprojection works on only one file, but not in shapefile tileitem. So Did I do something wrong, or this is it a bug from mapserv ?

Moreover, i am already using mapserver with the WMS service, and i have only shapefile tileitem entries on my wms mapfile : the reprojection works perfectly ! (the shapefile are created from the gdaltindex tool).

I can't put each file on my mapfile, because i thousands files and this will be affect the performances of mapserv (moreover, i think it exist a limitation of the maximum number of layers in a mapfile).

So do you would have any idea about this problem, or do you know an easy exemple of a wcs service server who delivers DEM data in differents reprojections ?

thanks you for the help,

sincerly,

Jérôme Martin




J'ai donc configuré un server wcs, et j'ai également crée un fichier shp via gdaltindex afin de n'avoir qu'une seule entrée dans le mapfile regroupant plusieurs fichiers DTED.

Je précise que les fichiers sont en latlon EPSG:4326

En faisant une requête avec CRS=epsg:4326, j'ai donc le résultat attendu, soit un fichier tiff (ce que je voulais) en latlon.
Par contre, lorsque je fais une requête avec CRS=epsg:32631 (UTM zone N31) par exemple, là, tout se complique puisque la réponse que me renvoye le server semble bonne au niveau des dimensions, mais je n'ai uniquement que des 0, les données d'élévation disparaissent.

Je précise que j'ai déjà un server WMS utilisant exclusivement des tileindex (via gdaltindex) et que la reprojection se passe parfaitement. Mais en WCS, rien ne marche plus pour la reprojection.

Par contre, si je prend un fichier seul (fichier.dt1) que je rajoute dans mon mapfile wcs, alors dans ce cas là, la reprojection marche bien et ne pose pas de problème. Je ne peux cependant pas résoudre mon problème comme cela car je ne peux inclure des milliers de fichiers dans mon mapfile, et je ne peux pas non plus modifier les fichiers dted en entrée (d'autant plus que je ne veux pas distinguer séparement chaque fichier dted dnas mes requêtes).

Comment puis-je résoudre mon problème ? quelqu'un a-t-il déjà été confronté à ce type de problème sous WCS ?

cordialement,

Jérôme Modifier/Supprimer le message
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Re: WCS and Reprojection with TileItem

Norman Barker

Hi Jerome,

 

I know Jeremy Morley doesn’t watch these lists too much, but his ICEDS service

 

http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?SERVICE=WCS&REQUEST=DescribeCoverage&Coverage=srtm

 

offers srtm data in different projections.

 

His website also gives full config details for MapServer configuration, a subset of which is on the MapServer website under WCS use cases.

 

Thanks,

 

Norman

 


From: UMN MapServer Users List [mailto:[hidden email]] On Behalf Of Jérôme Martin
Sent: 01 February 2007 01:06
To: [hidden email]
Subject: [UMN_MAPSERVER-USERS] WCS and Reprojection with TileItem

 

Hi,

I'm using mapserv like WMS and now, I would like use the WCS service to get DEM, from DTED files.

To do this, i used gdaltindex software to create a shapefile to have only one entry on my mapfile with the "TILEITEM" keyword.

I precise my dted file are LatLon, in EPSG:4326.

So when i did a request Getmap from the server, i had the result i wanted for, in lat-lon.
But my problem was when i tried to send the request, but with CRS=epsg:32631 (UTM Zone N31) by example (BBOX in 32631 too), nothing work and the server send me a file with the good boundingbox envelloppe, but with no data, only 0.

When I tried to do a resquest with CRS=epsg:4326 (BBOX in 4326)  and RESPONSE_CRS=epsg:32631, i have the same empty 0 file, and the server doesn't warn me any error. Just a file with 0m data elevation.

I'm really surprised, because the OGC documents about the WCS Service tell the response_crs can be used to have a reprojection, and the how-to user case from the mapserver website tell this option can be used.

So when i try to put only one file with the DATA keyword, i was really surprised to see a request in another crs gave me the good reprojection and the right results, so the reprojection works on only one file, but not in shapefile tileitem. So Did I do something wrong, or this is it a bug from mapserv ?

Moreover, i am already using mapserver with the WMS service, and i have only shapefile tileitem entries on my wms mapfile : the reprojection works perfectly ! (the shapefile are created from the gdaltindex tool).

I can't put each file on my mapfile, because i thousands files and this will be affect the performances of mapserv (moreover, i think it exist a limitation of the maximum number of layers in a mapfile).

So do you would have any idea about this problem, or do you know an easy exemple of a wcs service server who delivers DEM data in differents reprojections ?

thanks you for the help,

sincerly,

Jérôme Martin




J'ai donc configuré un server wcs, et j'ai également crée un fichier shp via gdaltindex afin de n'avoir qu'une seule entrée dans le mapfile regroupant plusieurs fichiers DTED.

Je précise que les fichiers sont en latlon EPSG:4326

En faisant une requête avec CRS=epsg:4326, j'ai donc le résultat attendu, soit un fichier tiff (ce que je voulais) en latlon.
Par contre, lorsque je fais une requête avec CRS=epsg:32631 (UTM zone N31) par exemple, là, tout se complique puisque la réponse que me renvoye le server semble bonne au niveau des dimensions, mais je n'ai uniquement que des 0, les données d'élévation disparaissent.

Je précise que j'ai déjà un server WMS utilisant exclusivement des tileindex (via gdaltindex) et que la reprojection se passe parfaitement. Mais en WCS, rien ne marche plus pour la reprojection.

Par contre, si je prend un fichier seul (fichier.dt1) que je rajoute dans mon mapfile wcs, alors dans ce cas là, la reprojection marche bien et ne pose pas de problème. Je ne peux cependant pas résoudre mon problème comme cela car je ne peux inclure des milliers de fichiers dans mon mapfile, et je ne peux pas non plus modifier les fichiers dted en entrée (d'autant plus que je ne veux pas distinguer séparement chaque fichier dted dnas mes requêtes).

Comment puis-je résoudre mon problème ? quelqu'un a-t-il déjà été confronté à ce type de problème sous WCS ?

cordialement,

Jérôme Modifier/Supprimer le message

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Re: WCS and Reprojection with TileItem

Jérôme Martin-4
Hi Norman,

I tried to do a request on his website, but i still have the same problem that i
 already have on my own server.

when i ask a simple resquest on the srtm (thanks for the link), i can see the
data on epsg:4326
http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?VERSION=1.0.0&SERVICE=WCS&REQUEST=GetCoverage&coverage=srtm&width=400&height=400&bbox=2,49,3,50&crs=epsg:4326&FORMAT=geotiff_int16
this links works fine, but they are no reprojection.

Now when i try to convert to the UTM zone on this data (France, north to Paris,
so UTM zone 31N : epsg:32631), i have only this :
http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?VERSION=1.0.0&SERVICE=WCS&REQUEST=GetCoverage&coverage=srtm&width=400&height=400&bbox=425000,5427000,500000,5539000&crs=epsg:32631&FORMAT=geotiff_int16
this links give me the good boundingbox but not the data inside ! only Om data
elevation !

Now if i add on this request : RESPONSE_CRS=epsg:32631, i have the same result,
http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?VERSION=1.0.0&SERVICE=WCS&REQUEST=GetCoverage&coverage=srtm&width=400&height=400&bbox=425000,5427000,500000,5539000&crs=epsg:32631&FORMAT=geotiff_int16&RESPONSE_CRS=epsg:32631

Now if i try the response_crs in 32631 and the crs in 4326 with bbox in 32631, i
have always this same 0m elevation data :
http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?VERSION=1.0.0&SERVICE=WCS&REQUEST=GetCoverage&coverage=srtm&width=400&height=400&bbox=425000,5427000,500000,5539000&crs=epsg:4326&FORMAT=geotiff_int16&RESPONSE_CRS=epsg:32631

So i really don't understand where is the problem.


Thanks for this site.

I will see now the zip we can find on the site to see the mapfile i used to do
this excellent and nice site.

But i'm still convinced mapserv has a bug because theses kinds of requests are
possible in WMS Service !

Cordialy,

Jérôme


Selon Norman Barker <[hidden email]>:

> Hi Jerome,
>
>
>
> I know Jeremy Morley doesn't watch these lists too much, but his ICEDS
> service
>
>
>
>
http://iceds.ge.ucl.ac.uk/cgi-bin/icedswcs?SERVICE=WCS&REQUEST=DescribeCoverage&Coverage=srtm

>
>
>
> offers srtm data in different projections.
>
>
>
> His website also gives full config details for MapServer configuration, a
> subset of which is on the MapServer website under WCS use cases.
>
>
>
> Thanks,
>
>
>
> Norman
>
>
>
> ________________________________
>
> From: UMN MapServer Users List [mailto:[hidden email]] On
> Behalf Of Jérôme Martin
> Sent: 01 February 2007 01:06
> To: [hidden email]
> Subject: [UMN_MAPSERVER-USERS] WCS and Reprojection with TileItem
>
>
>
> Hi,
>
> I'm using mapserv like WMS and now, I would like use the WCS service to get
> DEM, from DTED files.
>
> To do this, i used gdaltindex software to create a shapefile to have only one
> entry on my mapfile with the "TILEITEM" keyword.
>
> I precise my dted file are LatLon, in EPSG:4326.
>
> So when i did a request Getmap from the server, i had the result i wanted
> for, in lat-lon.
> But my problem was when i tried to send the request, but with CRS=epsg:32631
> (UTM Zone N31) by example (BBOX in 32631 too), nothing work and the server
> send me a file with the good boundingbox envelloppe, but with no data, only
> 0.
>
> When I tried to do a resquest with CRS=epsg:4326 (BBOX in 4326)  and
> RESPONSE_CRS=epsg:32631, i have the same empty 0 file, and the server doesn't
> warn me any error. Just a file with 0m data elevation.
>
> I'm really surprised, because the OGC documents about the WCS Service tell
> the response_crs can be used to have a reprojection, and the how-to user case
> from the mapserver website tell this option can be used.
>
> So when i try to put only one file with the DATA keyword, i was really
> surprised to see a request in another crs gave me the good reprojection and
> the right results, so the reprojection works on only one file, but not in
> shapefile tileitem. So Did I do something wrong, or this is it a bug from
> mapserv ?
>
> Moreover, i am already using mapserver with the WMS service, and i have only
> shapefile tileitem entries on my wms mapfile : the reprojection works
> perfectly ! (the shapefile are created from the gdaltindex tool).
>
> I can't put each file on my mapfile, because i thousands files and this will
> be affect the performances of mapserv (moreover, i think it exist a
> limitation of the maximum number of layers in a mapfile).
>
> So do you would have any idea about this problem, or do you know an easy
> exemple of a wcs service server who delivers DEM data in differents
> reprojections ?
>
> thanks you for the help,
>
> sincerly,
>
> Jérôme Martin
>
>
>
>
> J'ai donc configuré un server wcs, et j'ai également crée un fichier shp via
> gdaltindex afin de n'avoir qu'une seule entrée dans le mapfile regroupant
> plusieurs fichiers DTED.
>
> Je précise que les fichiers sont en latlon EPSG:4326
>
> En faisant une requête avec CRS=epsg:4326, j'ai donc le résultat attendu,
> soit un fichier tiff (ce que je voulais) en latlon.
> Par contre, lorsque je fais une requête avec CRS=epsg:32631 (UTM zone N31)
> par exemple, là, tout se complique puisque la réponse que me renvoye le
> server semble bonne au niveau des dimensions, mais je n'ai uniquement que des
> 0, les données d'élévation disparaissent.
>
> Je précise que j'ai déjà un server WMS utilisant exclusivement des tileindex
> (via gdaltindex) et que la reprojection se passe parfaitement. Mais en WCS,
> rien ne marche plus pour la reprojection.
>
> Par contre, si je prend un fichier seul (fichier.dt1) que je rajoute dans mon
> mapfile wcs, alors dans ce cas là, la reprojection marche bien et ne pose pas
> de problème. Je ne peux cependant pas résoudre mon problème comme cela car je
> ne peux inclure des milliers de fichiers dans mon mapfile, et je ne peux pas
> non plus modifier les fichiers dted en entrée (d'autant plus que je ne veux
> pas distinguer séparement chaque fichier dted dnas mes requêtes).
>
> Comment puis-je résoudre mon problème ? quelqu'un a-t-il déjà été confronté à
> ce type de problème sous WCS ?
>
> cordialement,
>
> Jérôme   <http://www.forumsig.org/editpost.php?do=editpost&p=93083>
>
>
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Re: WCS and Reprojection with TileItem

turtlewax
In reply to this post by Jérôme Martin-4
As of 5.6.4 I believe this is still an issue. I'm opening a ticket, but I'd like to document this exhaustively, so it will take some time.

I believe Tamas Szekeres provided a patch for this in 2008.
http://osgeo-org.1803224.n2.nabble.com/WCS-RESPONSE-CRS-and-BBOX-projection-td1974456.html#a1974456

This patch hasn't been committed to trunk. I can't say for certain if it will fix it. Currently, I'm setting up an environment to compile from source.  I'll apply this patch and hopefully report back with good results.



http://osgeo-org.1803224.n2.nabble.com/requestResponseCRSs-td1997820.html#a1997820
http://osgeo-org.1803224.n2.nabble.com/PATCH-WCS-reprojection-problem-fix-td1999146.html#a1999146