WCS sampling error

[Norman Barker]

-----Original Message-----
From: Frank Warmerdam [mailto:fwarmerdam at gmail.com]
Sent: Thursday, May 12, 2005 3:33 PM
To: Norman Barker
Cc: MAPSERVER-USERS at lists.umn.edu
Subject: Re: [UMN_MAPSERVER-USERS] WCS sampling error


On 5/12/05, Norman Barker <nbarker at rsinc.com> wrote:
> Hi,
> 
> I am using the WCS to serve geotiff files, it seems that if the values of RESX and RESY are not equal to the base
> resolution of the tiff image in the getCoverage request then the request fails with a black image being returned to the
> user.
> 
> So, if resx, resy are 1.125 say then it works fine, but then another file having a resolution value of 1.21211211.. reported by the geotiff file (so resolution to a few more than 2 decimal places) causes the resampling to occur and the image to be blank.
> 
> Do I have to truncate my values of resx, resy when I export to geotiff to put the files in the WCS?  This resampling will
> happen when I make other requests, will it also fail (I remember making reprojection requests with DEMs and this happened),
> any advice would be appreciated.

Norman, 

I think this is the same as the following bug, which I have been meaning
to revisit.  your note gives me a big clue as to what is going wrong. 

  http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1183

Best regards,
-- 

Hi Frank, 

thanks for the reply, is there any work around for this at the moment, or can you give me an indication of how we could fix it?  I will fix my files to have a fixed number of decimal points but
eventually it would be cool to be able to make requests at different resolutions.

Many thanks,

Norman Barker