The following data comes directly from S1B_IW_SLC__1SDV_20180426T063818_20180426T063845_010651_013707_1395.SAFE\annotation\s1b-iw1-slc-vv-20180426t063819-20180426t063844-010651-013707-004.xml:
-
2018-04-26T06:38:19.750001
GM2000
2.048773e-01
3.932928e-01
3.003435e-01
8.444761e-01
-5.878133015357889e-05
-9.468332864344120e-04
-4.792133113369346e-04
-6.302749733477862e+00
-5.238290812737592e+01
4.225907254185638e+01
I can not find *any* set of equations to convert from the provided quaternions (q0-q3) to pitch,roll,yaw and vice-versa. Yes, I have started with all of the ESA published documents and then expanded out to multiple other documents on the web. I have coded every variant I have encountered in Matlab, but am unable to get numbers that agree to even to the ones digit. I have even tried to use different application sequences (instead of just the published 3-2-1 order).
Worse from a documentation point of view, I believe that here Q3 is the magnitude, but almost all Sentinel-1 documentation defines Q0 to be the magnitude of the quaternion. I get that it is generally not consistent and/or both are acceptable - BUT a given system should be self-consistent.
As you might expect, this is a key step to being able to associate each formed image pixel with an exact ground coordinate. Without an understanding of how to apply (q0-q3) to be pitch,roll,yaw it is clear any attempt I take to use them for vehicle rotation/orientation will be wrong. "Close" isn't good enough - I need the full, exact understanding so I can precisely apply the vehicle orientation to my image formation.
Please, don't just point me to Wikipedia or some web page - try the numbers first - I have.