[GRASSLIST:5063] image alignment

GRASS GRASS user
1

I have a set of images, all of which are relatively of the same area, though
the images are all slightly offset. I need to either align all of the images
to a reference image or or be able to batch process the images to a set of
known ground coordinates.

Within each image, there are markers that have known xy coordinates. I
understand that I could use i.points and i.rectify for each individual image.
That would take quite a while as I have hundreds of images.

Is there a way to automatically align(and in some cases rescale) the images
automatically or in some batch process, or am I stuck with rectifying each
individual image?...or is there a better way to do this task altoghether?

Thanks in advance,

Mike

--
Michael W. Sears, Ph.D.
Department of Life Science
Indiana State University
Terre Haute, IN 47809

812-237-9638

2

On Mon, Nov 25, 2002 at 04:55:41PM -0800, Mike Sears wrote:

I have a set of images, all of which are relatively of the same area, though
the images are all slightly offset. I need to either align all of the images
to a reference image or or be able to batch process the images to a set of
known ground coordinates.

Within each image, there are markers that have known xy coordinates. I
understand that I could use i.points and i.rectify for each individual image.
That would take quite a while as I have hundreds of images.

Is there a way to automatically align(and in some cases rescale) the images
automatically or in some batch process, or am I stuck with rectifying each
individual image?...or is there a better way to do this task altoghether?

If you can script writing out the registration points for each image,
then use can bypass i.points and just run i.rectify. Also, i.rectify
works for image groups...

The registration points file format is a simple text file mapping image
coordinates to the target coordinate system.

--
"...the plural of anecdote is [not?] data." - attrib. to George Stigler

3

First you need that all images have the same region and area
You can do it with r.resample

Then, you can use the i.group command.
You create a group with the set of images and use i.rectify for the group.
Furthermore you need the i.target command

Camilo

----- Original Message -----
From: "Mike Sears" <msears@mama.indstate.edu>
To: <GRASSLIST@baylor.edu>
Sent: Monday, November 25, 2002 7:55 PM
Subject: [GRASSLIST:5063] image alignment

I have a set of images, all of which are relatively of the same area,

though

the images are all slightly offset. I need to either align all of the

images

to a reference image or or be able to batch process the images to a set of
known ground coordinates.

Within each image, there are markers that have known xy coordinates. I
understand that I could use i.points and i.rectify for each individual

image.

That would take quite a while as I have hundreds of images.

Is there a way to automatically align(and in some cases rescale) the

images

automatically or in some batch process, or am I stuck with rectifying each
individual image?...or is there a better way to do this task altoghether?

Thanks in advance,

Mike

--
Michael W. Sears, Ph.D.
Department of Life Science
Indiana State University
Terre Haute, IN 47809

812-237-9638