[ale] Interpreting "P" transformation data

[Joe R]

Ok, so "positive" is down and to the right. Got it.

Thanks again!


-j


--- On Mon, 6/15/09, David Hilvert <dhilvert at gmail.com> wrote:

> From: David Hilvert <dhilvert at gmail.com>
> Subject: Re: [ale] Interpreting "P" transformation data
> To: "Joe R" <vinnyjojo at yahoo.com>
> Cc: ale at ventricle.dyndns.org
> Date: Monday, June 15, 2009, 6:15 PM
> On Mon, 15 Jun 2009 14:20:25 -0700
> (PDT)
> Joe R <vinnyjojo at yahoo.com>
> wrote:
> 
> > Hello all,
> > 
> > I'm trying to use ALE to align a series of images and
> I'd like to make sure
> > I'm interpreting the transform output correctly. The
> way it's described, the
> > output for the projective transformation has its
> origin in the top left
> > corner of the image.
> > 
> > Here's the output for two files that are almost, but
> not quite, aligned:
> > P 400.000000 300.000000 -2.000000 -4.812500 -5.250000
> 295.562500 395.312500 300.687500 397.062500 0.687500 
> > 
> > Looking at --hA, the first coordinate after the size
> (-2.000000, -4.812500) is at the top left:
> > P <xmax> <ymax> <tlx> <tly>
> <blx> <bly> <brx> <bry> <trx>
> <try>
> > 
> > Is this the correct interpretation? My impression is
> that it'd lead to a
> > "flipped" image. Thanks!
> 
> The coordinate system has the origin at the top-left, which
> is a fairly common
> placement; hence, it's expected that the top-left
> coordinates in this example
> would be close to zero.
> 
>