[GRASS-dev] a suggestion for v.transform

There has been a thread about how v.transform functions and Glynn pointed
out that part of the problem is that the short description does not really
describe what it does, at least from a GIS perspective:

" Transforms a vector map layer from one coordinate system into another
coordinate system."

I'm working on wxgrass menus at the moment and trying to come up with useful
menu entries. A better short description for v.transform might be:

"Reposition (shift and rotate) vector file in coordinate space"

Thoughts?

Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

v.transform: perform affine transformation (translate and rotate) a
vector file.

See affine transformation in wikipedia.

John

Indeed. I recently did some stuff with v.transform / affine transformation.
perhaps I can summarize it, and include a helpful figure in the man page.

http://casoilresource.lawr.ucdavis.edu/drupal/node/433

specifically the shifted grid example:
http://casoilresource.lawr.ucdavis.edu/drupal/node/435

cheers,

On Thursday 14 June 2007 07:40, John Gillette wrote:

v.transform: perform affine transformation (translate and rotate) a
vector file.

See affine transformation in wikipedia.

John

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--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

Michael Barton wrote:

There has been a thread about how v.transform functions and Glynn pointed
out that part of the problem is that the short description does not really
describe what it does, at least from a GIS perspective:

" Transforms a vector map layer from one coordinate system into another
coordinate system."

I'm working on wxgrass menus at the moment and trying to come up with useful
menu entries. A better short description for v.transform might be:

"Reposition (shift and rotate) vector file in coordinate space"

Thoughts?

It can also scale.

--
Glynn Clements <glynn@gclements.plus.com>

On Thursday 14 June 2007 12:15, Glynn Clements wrote:

Michael Barton wrote:
> There has been a thread about how v.transform functions and Glynn pointed
> out that part of the problem is that the short description does not
> really describe what it does, at least from a GIS perspective:
>
> " Transforms a vector map layer from one coordinate system into another
> coordinate system."
>
> I'm working on wxgrass menus at the moment and trying to come up with
> useful menu entries. A better short description for v.transform might be:
>
> "Reposition (shift and rotate) vector file in coordinate space"
>
> Thoughts?

It can also scale.

... and to be complete, it can also shear.

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341

Dylan Beaudette wrote:

> > There has been a thread about how v.transform functions and Glynn pointed
> > out that part of the problem is that the short description does not
> > really describe what it does, at least from a GIS perspective:
> >
> > " Transforms a vector map layer from one coordinate system into another
> > coordinate system."
> >
> > I'm working on wxgrass menus at the moment and trying to come up with
> > useful menu entries. A better short description for v.transform might be:
> >
> > "Reposition (shift and rotate) vector file in coordinate space"
> >
> > Thoughts?
>
> It can also scale.

... and to be complete, it can also shear.

Only when using the pointsfile= option; there isn't any direct way to
specify a transformation which includes shear.

--
Glynn Clements <glynn@gclements.plus.com>

On 6/15/07, Glynn Clements <glynn@gclements.plus.com> wrote:

Dylan Beaudette wrote:

> > > There has been a thread about how v.transform functions and Glynn pointed
> > > out that part of the problem is that the short description does not
> > > really describe what it does, at least from a GIS perspective:
> > >
> > > " Transforms a vector map layer from one coordinate system into another
> > > coordinate system."
> > >
> > > I'm working on wxgrass menus at the moment and trying to come up with
> > > useful menu entries. A better short description for v.transform might be:
> > >
> > > "Reposition (shift and rotate) vector file in coordinate space"
> > >
> > > Thoughts?
> >
> > It can also scale.
>
> ... and to be complete, it can also shear.

Only when using the pointsfile= option; there isn't any direct way to
specify a transformation which includes shear.

Yes, good (point) . It would be an interesting add-on, to manually
specify the components of the affine transformation matrix. perhaps in
addition to the existing manual adjustments. Maybe I will have a try
at this.

cheers,

dylan

John Gillette wrote:

v.transform: perform affine transformation (translate and rotate) a
vector file.

See affine transformation in wikipedia.

John

I have update the one line description of the module. It would be good
to get the description.html extended, too.

Markus
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