Demonstration of using a Range-Doppler geometry engine (isce3) to precisely simulate Polar Format geometry for Staring Spotlight data (sarpy). A short technical note related to this work can be found here.
Links to the latest standard documents can be found here.
python3 pfa2rda.py {SICDfile}In general, the maximum forward mapping error is in the order of 10^{-5} meters and inverse mapping error is on the order of 10^{-7} pixels.
> python3 pfa2rda.py bangalore/2024-02-23-04-37-05_UMBRA-04_SICD.nitf
Testing inverse mapping
Row - column differences in pixels
[[-6.18456397e-11 -2.51020538e-10]
[-1.49437255e-07 1.69515260e-07]
[ 6.02994987e-10 1.69733539e-07]
[-8.98871804e-08 -2.28363206e-07]
[ 6.56655175e-10 -1.71312422e-07]]
Testing forward mapping
ECEF coordinates error in meters
[[ 1.12722628e-05 -8.78795981e-06 1.11013651e-06]
[ 1.18152238e-05 -8.94442201e-06 1.18720345e-06]
[ 1.12962443e-05 -8.78982246e-06 1.08778477e-06]
[ 1.07840169e-05 -8.65105540e-06 1.04377978e-06]
[ 1.12489797e-05 -8.78795981e-06 1.13178976e-06]]
Testing solution for SCP
SCP Time diff (s) Slant range diff (m)
[[ 5.34461364e-13 -1.16415322e-09]
[-3.21959126e-11 8.98726285e-08]
[-3.20953264e-11 8.92905518e-08]
[ 2.57748267e-11 -7.25267455e-08]
[ 6.74682532e-13 -2.91038305e-09]]
Forward mapping over grid
Max abs error in meters
[1.19619537e-04 9.31071118e-05 1.18145254e-05]
Inverse mapping over grid
Max abs error in pixels
[8.07785909e-08 2.18449713e-07]
Sarpy round trip
Max abs error in pixels
[7.58527676e-08 1.33877620e-08]
isce3 round trip
Max abs error in pixels
[1.01563273e-08 7.69796316e-09]