Re: Image-to-image registration.

On May 21, 9:45 am, aruzinsky <aruzin...@xxxxxxxxxxxxxxxxxxxx> wrote:
On May 21, 8:18 am, Yalin <mjm_v...@xxxxxxxxx> wrote:

Hello:

I am trying to do change detection between to years of a lake, and have had
a hard time getting the two images to  line up accurately.  I have to make
sure that the accuracy of the two images are <0.5 pixels apart.  I was
wondering if anyone can give me some advice or direct me to some
information on the image-to-image registration process.  I was using ILWIS
3.4, but now have IDRISI Amdes 15.0.  Is it essential that I have GCP for
the two images?

Post a link to the two images.

You cannot do rigid alignment of changed features such as trees that
have grown and/or been cut down.  Doing non-rigid alignment would
defeat the purpose of detecting changes.  Thus, you should do manual
registration of stable features.  To do manual alignment at subpixel
accuracy, it may be necessary to enlarge the images before alignment,
then reduce after alignment.

GCP ?= German Communist Party,http://en.wikipedia.org/wiki/GCP

You should try free demo version of SAR Image Processor,http://www.general-cathexis.com/.


Are you talking about locally rigidly registering features like trees?
Trees are an example of features that may have changed (their
projection on the LandSAT may have transformed in a non-rigid manner).
Hence talking about a local rigid registration for non-rigidly
changing features does not make sense in the first place. Why say a
thing that doesnt make sense and then state the obvious?

There could always be rigid structures in the images that do not
change shape. Such features (such as boundary of a lake, or land)
could be registered rigidly (selectively), and the resulting global
transform would give an idea of change in other features. I highly
recommend an automatic affine registration method. Look for opensource
projects (OpenCV e.g.).

If that does not work, you may try a manual affine registration
(rotation, translation, scaling). Unfortunately I am not aware of a
free software that will allow manual registration of LandSat images.
If you google, you will sure find some that are paid software.

And what is all this with finding weird expansions for GCM? If you
google GCM, you dont see this expansion on the first page. Keep the
replies to the point.


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