Thursday, February 15, 2007

Finding Jim Gray: Approximate Data Fusion/ An inference problem


We are dealing with an inference problem of the worst kind. Trying to find a target of unknown spectral signature in a different areas over time knowing that it moved over time. The drift models are essential in figuring out how the same target can be transported from location to another. We are also facing the fact that there are many elements, also of unknown signature that do not follow the drift models (because they are doing everything possible to go from point A to point B) or are spectrally equivalent to our target of interest. In other words we have to find a target of interest for which, given a drift model, is consistently identified when weather permits as being in the near vicinity of a target as detected by the different sensors and means of acquisition. In particular, the question of why the coast Guards did not see anything on Feb 1 must be answered.


Day 2.6

Day 4.8
Day 5.1

Maria Nieto-Santisteban and Jeff Valenti at John Hopkins University (The JHU group) have used the ocean current models provided by the OurOcean folks at JPL to create an animated GIF of how markers move with the currents. Relevant satellite and aerial imagery were obtained 2.6, 4.8, 5.1, and 5.8 days after the adopted zero point in time (Jan 29, 00:00 GMT).

The Radarsat images do not suffer from the clouds or fog. They were also taken very early on the search (Jan 31 and Feb 3). Quickbird and Ikonos shots would be useful in evaluating if any of the radar targets are of interest. My assumption is that Tenacious responded to the radar but was probably covered by clouds when visible light satellite or planes (ER-2) passed over it.
Following this thinking, I produced a kml file for the Radarsat images as processed by Maria and Jeff (it needs to be polished, anybody ?) and probably needs to have the ER-2 data. The Mechanical Turk data findings are not available online. One can see part of the kml file directly on Google Maps but it does not display well because it is too big for Google Maps in this fashion.

The major capability provided by the JPL folks is in the ability to remove targets that are really false positives. And so instead of looking at ocean current models and try to fit the targets found by Radarsat, it would be interesting to figure out how targets on Jan 31 found by Radarsat were transported to another position on Feb 3 using the model. By evaluating the distance between targets of Jan 31 transported by the JPL model and actual targets found on Feb 3, we would have a good view of the ones for which the model is accurate. Then, we could evaluate if any of the targets found by Quickbird on Feb 2 and Feb 3 are anywhere close (why use the radarsat images first) It is also of paramount importance that one uses the JPL current models with a grain of salt. This is fluid mechanics after all.

By eyeballing the Radarsat targets and the crosses of the JPL model, one seem to see some similar features pointing to the potential correctness of the ocean current model. Some of targets could be removed using the Quickbird imagery.



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