[Insight-users] registration of satellite images

[Luis Ibanez]

Hi Yannick,

Thanks for sending your images.

The Panchromatic image looks fine, but the Backscattered image
doesn't seems to have the correct pixels dimensions.

You mentioned spacing 4m x 0.75m for this image, but I had to go
as low as 4m x 0.25m in order to get an image with visually
acceptable aspect ratio.


Once the spacing fixed, the original mis-registration seems
to be in the order of 135 degrees.


Please double check your values of spacing, and then proceed
to estimate an appropriate origin again.

The simple way of doing this is to use the ImageViewer application
from InsightApplications/ImageViewer and click in some landmarks
of your Panchromatic image. ImageViewer will give you coordinates
of those landmarks.   Then proceed to click on the same landmarks
on the Backscattered image. From those coordinate you should be
able to compute an initialization for the origin of the images.


Note that you must use MutualInformation for registering these
two images, if you are doing intensity based registration.


Please find attached the two MetaImage headers for your PGM images,
with these header will be very easy for you to adjust the Origin
and Spacing of your images.

Origin is the field  :  "Position"
Spacing is the field :  "ElementSpacing"

Once you fine tune the values in these headers, you pass these
headers (*.mhd) to the ImageFileReaders of your application.
The reader will take the image origin and spacing from the
MetaImage header and the binary pixel data from the PGM files.




Note tha in order to view the images you *must* use a viewer that
takes pixel spacing into account. Here are some options of viewers
that will read MetaImages directly:

    1) InsightApplications/Auxiliary/vtk/itkReadITKImageShowVTK (simplest)

    2) InsightApplications/ImageViewer (intermediate level application)

    2) ParaView (www.paraview.org) Free and Open Source (full application)
       With ParaView you can easily customize the settings for the "Actor
       Control" in the Display tab, and manually set values for the
       rotation and translation of the images.




     Regards,


        Luis


-------------------------------------------------------------------------------
> Hi Luis,
> 
> I've manually enter a valid origin for both images and it still dont work. All
> the samples falls outside the moving image. Any Idea? Here are the images that
> I'm trying to automatically coregistered. Spacing of the Pan is 1m x 1m, spacing
> of the backscatter is 4m x 0.75m
> 
> 
> 
> 
> Thank you 
> Yannick

=============================================






-------------- next part --------------
ObjectType = Image
NDims = 2
BinaryData = True
BinaryDataByteOrderMSB = False
DimSize = 126 1184
ElementSpacing = 4.0 0.25
Position = 0.0 0.0
ElementType = MET_UCHAR
HeaderSize = -1
ElementDataFile = BackscatterHH_dB.pgm


-------------- next part --------------
ObjectType = Image
NDims = 2
BinaryData = True
BinaryDataByteOrderMSB = False
DimSize = 596 644
ElementSpacing = 1.0 1.0
Position = 0.0 0.0
ElementType = MET_UCHAR
HeaderSize = -1
ElementDataFile = Panchromatic.pgm