[Numpy-discussion] Help req: IDL --> Numeric/numarray
rays at san.rr.com
Tue Aug 31 07:05:10 CDT 2004
The current IDL REBIN() thread reminded me to post this here...
I'm trying to port Dr. Hongjie Xie's IDL/ENVI Implementation of the FFT
Based Algorithm for Automatic Image Registration (it calculates shift,
scale and rotation for 2d arrays)
to Python/numarray/Numeric and running into some subtle problems.
For instance, the IDL ROT() requires some additional steps to emulate, and
the MAX(array, position) as well.
And, I'm not at all familiar with the correspondence of the FFT
libraries... even the simple shift-only routine I translated
produces different (incorrect) x shift values than the IDL.
My current code
conforms to Xie's flow as much as possible for now, but should and will be
re-factored when functional; his LogPolar function, to convert rectangular
coordinate arrays to polar, is particularly slow.
I was recently informed that IDL has a usable demo version which I will try
this week, but I would love to hear if anyone else has interest in this.
I think that the algorithm would make a nice standalone module, or perhaps
something for nd_image.
Xie's main examples are registration of satellite Earth imagery, but it
should work just as well looking up ;-)
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