[Qgis-user] Prompt for projection when importing raster - QGIS 2.6

Thu Nov 27 21:01:47 PST 2014

Hi Brett,

Nicolas, is right I'm afraid.

If you can send some of the suspects (or put somewhere accessible) I'm happy to help find a work around / file bug / find a solution. 

-ramon.

> On 28 Nov 2014, at 11:44, Nicolas Cadieux <nicolas.cadieux at archeotec.ca> wrote:
> 
> Qgis will only ask for a projection if it is not embedded in the tif and you have selected the "ask for CSR" if its not specified.  If it is specified, (but wrong) then I am not sure how to force it.  I think you can specify a CSR when you right click on a layer name. I have seen this option go by but never used it and I am not sure what it does.
> 
> My first reaction would be to try the "assign projection" that uses gdal_warp.  You seem to have had a bit of an issue with that :(  It would be nice to try and replicate this problem so we could do a bug report. (Did you use the same directory to open and save the file?) I have never seen this one before.
> 
> My second option would probably be to use a linear algorithm in the georeferencing module in order to see if you could create a world file that could then be modified with a text editor but this is a guess.  I think you can also specify a wold file and a new projection in the "save as" but I am far from a box now so I can't check.
> 
> Well it seem you have found the problem with the wrong CRS so I am happy for you and I wish you the best.
> 
> Nicolas Cadieux M.Sc.
> Les Entreprises Archéotec inc. 
> 8548, rue Saint-Denis Montréal H2P 2H2
> Téléphone: 514.381.5112  Fax: 514.381.4995
> 
> Le 2014-11-27 20:51, "Brett Adams-2 [via OSGeo.org]" <[hidden email]> a écrit :
> How do I force QGIS to ask for a projection?    None of the options under Settings>>Options>>CRS enforce this.     QGIS sees the tif has a projection, doesn’t recognise it, then assigns it with unrecognised WGS84 based projection.
> 
>  
> 
> Tried running raster/ projection/ assign projection in batch mode.  It deleted all of the tif images!  That’ll have to be a separate thread but I guess it’s not a common problem.
> 
>  
> 
> I was able to trace the projection problem back to the original gridded image used to create the tif.   The grid used GDA94 / MGA51S instead of GDA94/ MGA51.  Image processing accepted 51S but when it wrote the tiff it wasn’t able to assign a sensible projection.     So QGIS got it right
> 
>  
> 
> brett
> 
>  
> 
> From: Nicolas Cadieux [mailto:[hidden email]] 
> Sent: Thursday, 27 November 2014 10:01 PM
> To: Brett Adams
> Subject: RE: [Qgis-user] [QGIS-user] Prompt for projection when importing raster - QGIS 2.6
> 
>  
> 
> Hi
> 
> When you open a file and then Qgis asks for a projection, where does the file end up? Is it at the right coordinate but in the wrong CRS or is it near 0,0?
> 
> If its near 0,0 then it's not georeferenced.  If it's in the right coordinates but in the wrong place, then the EPGS code is not in the .tif
> 
> If you use gdalinfo (raster \ Miscellaneous \ information), do you see  the line "authority ["EPSG...] Under  the line " unit"?  Can you see the code of your projection?
> 
> In MapInfo, the projection may be in a .tab file (or an other text file) or in the workspace so isolate the file in a folder and try opening it in blank workspace.  If it is not is the right spot, then MapInfo is not getting the information from the .tif
> 
> I just checked and you can use raster/ projection/ assign projection in batch mode. No need for Processing. 
> 
> Nicolas Cadieux M.Sc.
> Les Entreprises Archéotec inc. 
> 8548, rue Saint-Denis Montréal H2P 2H2
> Téléphone: 514.381.5112  Fax: 514.381.4995
> 
> Le 2014-11-27 02:17, Brett Adams <[hidden email]> a écrit :
> 
> Nicolas,
> 
>  
> 
> Tried setting  "use project CRS" when CRS is not specified.  However I’m guessing there is a difference between unrecognised and not set.  So this didn’t help.
> 
>  
> 
> The TIF files are georeferenced. They load into Mapinfo with the correct projection so I’m confident the information is there.
> 
>  
> 
> I’ll need to read up on the processing plugin, its not something I’ve ever used.
> 
>  
> 
> I thought there was an option such that all imported raster data had to be defined on import?
> 
>  
> 
> BA
> 
>  
> 
> From: [hidden email] [[hidden email]] On Behalf Of Nicolas Cadieux
> Sent: Thursday, 27 November 2014 10:16 AM
> To: [hidden email]
> Subject: Re: [Qgis-user] [QGIS-user] Prompt for projection when importing raster - QGIS 2.6
> 
>  
> 
> Hi,
> In your default CSR options, set "use project CRS" when CRS is not specified.  The CSR may not be included in the .tif files even if it is georeferenced. You can probably use the processing plugin to batch that.
> 
> Nicolas Cadieux M.Sc.
> Les Entreprises Archéotec inc. 
> 8548, rue Saint-Denis Montréal H2P 2H2
> Téléphone: 514.381.5112  Fax: 514.381.4995
> 
> Le 2014-11-26 20:45, "Brett Adams-2 [via OSGeo.org]" <[hidden email]> a écrit :
> 
> Hi Folks,
> 
>  
> 
> How do I set QGIS 2.6 to prompt for projection when importing a raster file with a projection it doesn’t recognise?
> 
>  
> 
> The TIF images are GDA94/MGA zone51 but for some reason it doesn’t always recognise the projection.    I know they can be reset later, but when theirs 20 images that gets a bit laborious.
> 
>  
> 
> Thanks
> 
> Brett
> 
> 
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