[GRASS-dev] [GRASS GIS] #2336: Vector map shifted in the map display

#2336: Vector map shifted in the map display
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Reporter: hcho | Owner: grass-dev@…
     Type: enhancement | Status: new
Priority: normal | Milestone: 7.1.0
Component: Display | Version: svn-trunk
Keywords: d.rast.arrow | Platform: All
      Cpu: All |
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I don't have this problem until I draw flow arrows (Add raster flow
arrows). When I click this menu, I'm asked to change the display
resolution. If I click No, the resolution looks very high (I think it's 1
arrow per pixel) and everything is just green (the default arrow color).
If I click Yes as recommended, raster cells in the display become
perfectly aligned with the display borders and arrows are drawn as
expected. So far, so good.

Now, if I add a polygon vector map representing cell boundaries, the lines
don't perfectly match with the raster cells (shown in the attached
screenshot). IMO, if I choose to align raster cells with the display
borders, vector coordinates have to be transformed such that they are also
snapped to the nearest cell vertices... Hmm... in some case, we may not
want this.

OR can we not change the display resolution at all and display arrows
correctly (one arrow per cell, not one arrow per pixel)?

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2336&gt;
GRASS GIS <http://grass.osgeo.org>

#2336: Vector map shifted in the map display
--------------------------+-------------------------------------------------
  Reporter: hcho | Owner: grass-dev@…
      Type: enhancement | Status: closed
  Priority: normal | Milestone: 7.1.0
Component: Display | Version: svn-trunk
Resolution: invalid | Keywords: d.rast.arrow
  Platform: All | Cpu: All
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Changes (by hcho):

  * status: new => closed
  * resolution: => invalid

Comment:

Ah! Now, I remember I added the -a flag just for this purpose. IMHO, it's
better to use -a by default without constraining the display resolution to
computational settings.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2336#comment:1&gt;
GRASS GIS <http://grass.osgeo.org>

#2336: Vector map shifted in the map display
--------------------------+-------------------------------------------------
  Reporter: hcho | Owner: grass-dev@…
      Type: enhancement | Status: reopened
  Priority: normal | Milestone: 7.1.0
Component: Display | Version: svn-trunk
Resolution: | Keywords: d.rast.arrow
  Platform: All | Cpu: All
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Changes (by hcho):

  * status: closed => reopened
  * resolution: invalid =>

Comment:

IMO, aligning vector lines and cell boundaries is still a valid point.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2336#comment:2&gt;
GRASS GIS <http://grass.osgeo.org>