DOI-USGS / usgscsm

This repository stores USGS Community Sensor Model (CSM) camera models
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Generic line scan camera's ground to image iteration is very inefficient #30

Closed jessemapel closed 6 years ago

jessemapel commented 6 years ago

The generic line scan camera uses Newton's method to calculate sample and line. Looking at some of the literature on this problem, that looks like a possibly poor method.

See: https://www.asprs.org/wp-content/uploads/pers/1993journal/may/1993_may_655-661.pdf https://www.asprs.org/wp-content/uploads/pers/2001journal/april/2001_apr_449-452.pdf https://www.asprs.org/wp-content/uploads/pers/2009journal/september/2009_sep_1059-1067.pdf

We should at the very least switch to solving for line (down-track) and then sample (across-track). ISIS uses a bisecting window search method, that we should consider implementing.

jessemapel commented 6 years ago

Another good reference about pushbrooms in general http://users.rsise.anu.edu.au/hartley/public_html/Papers/pushbroom/pushbroom.pdf

jessemapel commented 6 years ago

More references http://www.isprs.org/proceedings/XXXVII/congress/3b_pdf/14.pdf

jessemapel commented 6 years ago

CCPS search is probably not going to work because it requires consistent integration times and viewing angles.

jessemapel commented 6 years ago

We should start with the bisecting window search.

From Wang et al:

The first step of this method is to choose an image interval between the first and the last scanline as the initial search window. Then, it iteratively halves the search window by comparing the three pairs of image point coordinates calculated through colinearity equations, respectively, by employing the EO parameters of the first, the middle, and the last scanline of the search window. Finally, a sequential search is carried out in the final bisecting window within a threshold size

This is basically what ISIS3 does

jessemapel commented 6 years ago

Another more detailed resource for bisection search, see page 42

https://earth.esa.int/documents/700255/1929094/N77D7-PV02-US-5-IQC-GC-ATBD-ACS-0102-2.1/582f28ab-707c-4640-997c-8073d16d224f