[GRASS-dev] [GRASS GIS] #845: r.proj[.seg]: new flag to show reprojected bounds and exit

[GRASS GIS]

#845: r.proj[.seg]: new flag to show reprojected bounds and exit
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 Reporter:  hamish       |       Owner:  grass-dev at lists.osgeo.org
     Type:  enhancement  |      Status:  new                      
 Priority:  normal       |   Milestone:  6.5.0                    
Component:  Raster       |     Version:  svn-develbranch6         
 Keywords:  r.proj       |    Platform:  All                      
      Cpu:  All          |  
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 Hi,

 the current v.in.region + v.proj method for finding/setting the output
 region prior to running r.proj successfully is a time wasting pain in the
 neck. the attached patch adds two flags to r.proj (-p and -g) to display
 the bounds of the input map reprojected into the present location's
 projection.
 if it gets rotated along the way I'm not sure if these numbers will be at
 the far corners or in the middle of the source box.

 patch is vs. 6.5svn's raster/r.proj.seg/main.c but applies to trunk's
 r.proj ok.


 another idea is to have another new flag to automatically adjust the
 output map's region like the r.in.* modules would. But then resolution
 will typically be broken and you still have to fix that by hand, so I'm
 not sure how much that gains you. IIRC i.rectify has some code for
 figuring out the output resolution based on the input, but IIRC that is
 simplistic based on number of rows and columns and so it's buggy if there
 is much north-rotation between the two locations. IIRC the ticket for that
 bug is in the old RT bug tracking system, and a possible solution is to
 multiply ew,ns resolution by the cosine of the convergence angle. So for
 now I prefer to set the output resolution by hand.


 comments?

 Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/845>
GRASS GIS <http://grass.osgeo.org>