[R] off-topic: affine transformation matrix
Prof Brian Ripley
ripley at stats.ox.ac.uk
Tue May 29 00:18:51 CEST 2007
Isn't this just a regression (hopefully with a near-zero error).
coef(lm(cbind(xnew, ynew) ~ xold + yold))
should do what I think you are asking for. (I am not clear which
direction you want the transformation, so choose 'old' and 'new'
On Mon, 28 May 2007, Dylan Beaudette wrote:
> This may sound like a very naive question, but...
> give two lists of coordinate pairs (x,y - Cartesian space) is there any
> simple way to compute the affine transformation matrix in R.
> I have a set of data which is offset from where i know it should be. I have
> coordinates of the current data, and matching coordinates of where the data
> should be. I need to compute the composition of the affine transformation
> matrix, so that I can apply an affine transform the entire dataset.
> any ideas?
> thanks in advance!
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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