[Qgis-user] Re: vector affine transformation

[Agustin Lobo]

The problem with "Capture From Map Canvas" is
that you need 2 canvas, unless both the original and the reference 
objects are
be very close. The Georeferencer plugin opens the raster to be
processed in a special window, but that window does not
let you display a vector. Perhaps that would be enough, a window
such as the one in Georeferencer but for vectors.

By now, I'm going to try using Coordinate capture twice, once for the
vector to be warped and the other for the reference object. Then
input both sets of coordinates into R and calculate
the affine transformation matrix there. Then I can either
go on with the actual transformation in R (package spatstat)
and then export to QGIS (this is comfortably done thanks to
manageR) or use your plugin.

Agus

Maurício de Paulo wrote:
> Hum... you mean like georreferencing the vectors?
> While reading your mail I thought about a "Capture From Map Canvas" for 
> the two translation coordinates.
> Well, I don't know how the georreferencer is written, but I can try to 
> think about reusing it's code. I'm going to take a look at it.
> Thanks for the tip.
> Best regards,
> Mauricio de Paulo
> 
> On Fri, Nov 27, 2009 at 9:36 AM, Agustin Lobo <aloboaleu at gmail.com 
> <mailto:aloboaleu at gmail.com>> wrote:
> 
>     Hi!
> 
>     It's often the case in which you actually don't know
>     the values for the affine transformation for
>     plugin qgsAffine but just some pairs of corresponding coordinates.
>     I understand that including a facility such as the one for raster
>     georeference would be very useful but quite a work, thus I wonder
>     if the raster georeference plugin could actually output this
>     information which could then be fed to qgsAffine?
> 
>     Agus
>     -- 
>     Dr. Agustin Lobo
>     Institut de Ciencies de la Terra "Jaume Almera" (CSIC)
>     LLuis Sole Sabaris s/n
>     08028 Barcelona
>     Spain
>     Tel. 34 934095410
>     Fax. 34 934110012
>     email: Agustin.Lobo at ija.csic.es <mailto:Agustin.Lobo at ija.csic.es>
>     http://www.ija.csic.es/gt/obster
> 
>