[GRASS-dev] Re: [GRASS GIS] #663: Zooming in too far causes vector weirdness

[GRASS GIS]

#663: Zooming in too far causes vector weirdness
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  Reporter:  epatton  |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect   |      Status:  new                      
  Priority:  normal   |   Milestone:  6.4.0                    
 Component:  wxGUI    |     Version:  svn-develbranch6         
Resolution:           |    Keywords:                           
  Platform:  Linux    |         Cpu:  x86-64                   
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Comment (by hamish):

 this is a very, very, very, very old bug. Try filled polygons for more
 weirdness. (I had a quick look on the old RT bug system but didn't see an
 open ticket, anyway it dates back at least before 5.0.0) The real question
 is if it is still present in the new GRASS 7 display library.

 > I can't determine at what scale this seems to occur, as the map
 > scale isn't displaying correctly either (it only shows 1:0 at
 > all zoom levels, even when zoomed to full extent of map).

 FWIW a 1:x map scale is fairly useless/wrong on a monitor. It's
 only really of use on a printed page of fixed size. To calculate it
 correctly you need to know the exact dpi and dimensions of the monitor,
 and X-Windows (if available) only gives you an untrusted guess at that.
 The GIMP provides a calibration GUI where you put a ruler up to the scale
 on the screen and you type in the number of millimeters between the marks
 on the screen. While it is somewhat useful for giving you a quick idea of
 the map extent, it presents the user with a misleading sense of precision,
 and I find shipping known-bad data to be unpleasant. Also for lat/lon I
 expect the x and y axes being of different scales away from the equator
 makes the concept even more absurd.


 better to follow the changing coordinate values as you move the mouse
 around.



 Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/663#comment:2>
GRASS GIS <http://grass.osgeo.org>