[GRASS-dev] [GRASS GIS] #1928: after v.transform v.to.db gives incorrect length

#1928: after v.transform v.to.db gives incorrect length
-------------------------+--------------------------------------------------
Reporter: pertusus | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Keywords: | Platform: Linux
      Cpu: Unspecified |
-------------------------+--------------------------------------------------
I import a dxf without georeferenced information, then scale it with
v.transform. After that the line length obtained through v.to.db is wrong.
If I export the line with v.out.ascii and reimport it, the length is
correct.

A tarball to reproduce is attached.

{{{
tar xzvf bug_grass.tar.gz
cd bug_grass
./reproduce.sh
}}}

The script will show the lengths that are much lower than the correct
length (should be like 3300 for the first line, for instance).

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1928&gt;
GRASS GIS <http://grass.osgeo.org>

#1928: after v.transform v.to.db gives incorrect length
-------------------------+--------------------------------------------------
Reporter: pertusus | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Keywords: | Platform: Linux
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by mmetz):

Replying to [ticket:1928 pertusus]:
> I import a dxf without georeferenced information, then scale it with
v.transform. After that the line length obtained through v.to.db is wrong.

The bug in v.to.db is that it does not use geodesic distance calculations
in latitude-longitude projections. Fixed in trunk r55729.

Markus M

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1928#comment:1&gt;
GRASS GIS <http://grass.osgeo.org>

#1928: after v.transform v.to.db gives incorrect length
-------------------------+--------------------------------------------------
Reporter: pertusus | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Keywords: | Platform: Linux
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by mmetz):

Replying to [comment:1 mmetz]:
> Replying to [ticket:1928 pertusus]:
> > I import a dxf without georeferenced information, then scale it with
v.transform. After that the line length obtained through v.to.db is wrong.
>
> The bug in v.to.db is that it does not use geodesic distance
calculations in latitude-longitude projections.

Applies to 3D vectors only.

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1928#comment:2&gt;
GRASS GIS <http://grass.osgeo.org>

#1928: after v.transform v.to.db gives incorrect length
-------------------------+--------------------------------------------------
Reporter: pertusus | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Keywords: | Platform: Linux
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by pertusus):

It works now. It also affects 6.4.3svn. Do you want that I apply the
changeset patch and test there?

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1928#comment:3&gt;
GRASS GIS <http://grass.osgeo.org>

#1928: after v.transform v.to.db gives incorrect length
-------------------------+--------------------------------------------------
Reporter: pertusus | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Keywords: | Platform: Linux
      Cpu: Unspecified |
-------------------------+--------------------------------------------------

Comment(by mmetz):

Replying to [comment:3 pertusus]:
> It works now. It also affects 6.4.3svn. Do you want that I apply the
changeset patch and test there?

Tested and backported with r55746-7.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1928#comment:4&gt;
GRASS GIS <http://grass.osgeo.org>

#1928: after v.transform v.to.db gives incorrect length
-----------------------+----------------------------------------------------
  Reporter: pertusus | Owner: grass-dev@…
      Type: defect | Status: closed
  Priority: normal | Milestone: 6.4.3
Component: Vector | Version: svn-releasebranch64
Resolution: fixed | Keywords:
  Platform: Linux | Cpu: Unspecified
-----------------------+----------------------------------------------------
Changes (by pertusus):

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

Comment:

Tested too in 6.4.3 svn branch, it works, closing now, thanks.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1928#comment:5&gt;
GRASS GIS <http://grass.osgeo.org>