Sunday, November 18, 2007

Open Source SAR Analysis - Story of RAT

I have a few more minutes at the airport, the flight is delayed. This is a good time as any to announce that now I am an official RAT - Radar Toolkit developer with commit access to the berlios svn. My contributions so far are only in the "IO" segment, ALOS-PALSAR CEOS, TerraSAR-X COSAR and XML metadata loaders. I am hoping to contribute some dual-polarimetry analysis tools as my skills develop.

SAR is a very specialized sensor without wide spread application, as such good SAR programs are few and far between. Most so called commercial packages are half-hearted commercialization attempts from university research groups. RAT is a robust open-source alternative chiefly developed by the enthusiastic Andreas Reigber at the Technical University of Berlin. IDL is the language of choice for these folk, it is similar to Matlab, high-level and and mainly procedural. Obejct and events support are sort of patched on. Other attempts at similar toolkits have been by Atlanta Scientific-Vexcel-MDA using Python-C base and an OpenEV viewer and by ESA in TCL (PolsarPRO) but neither of these in my opinion offers the easy extensibility and ease of use of RAT, provided you somehow procure an IDL licence. I similar parallel toolkit in Matlab will also come in handy, but the development of this has been sporadic, I really need to dig up the bits I wrote during my undergraduate work and start something going.

One of the best SAR features in RAT so far in my exploration is the LLMMSE Speckle filter, it produces a clear image from the standard speckled SAR image.

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