1. 3MI SAG #4 Action Item
Analysis of PSF and co-registration error contributions
Ruediger Lang, Gabriele Poli, Rose Munro,

2. Various PSFs for testing
PSF ESA “Best”
PSF Box Cart
PSF Gauss
PSF ESA “Worst”

3. MTF EURD requirements VII and 3MII
VII requirements
3MI requirements
3MI-MTF(fnyq)
3MI-MTF(fnyq)
3MI-MTF(fnyq)
EUM/PEPS/REQ/09/0151 v3L

4. MTF from PSF ESA “Worst” Without detector sampling
PSF by ESA “Worst”

5. MTF from PSF ESA “Best” Without detector sampling
PSF by ESA “Best”

6. Co-registration error Using VII test-data as reference field
Mapping of VII test data to 509 by 509 regular grid
using 9 by 9 sub-matrices of VII data
per 3MI detector pixel. +
convolution with (various) PSF.
3MI PSF “best”
by ESA
3MI PSF “worst”
by ESA
EPS-SG VII test-data radiances / LOA
4581 by 4581 reference matrix convolved with (various) PSF

7. Co-registration error Using VII test-data as reference field – Constructing reference and target
Illustration of the comparison using a focus on the terrain:
Reference
(with illustrated sampling principle for the reference)
Target: High resolution, convolved matrix
sampled at 3MI resolution (509 by 509)
(with real projection of regular ground grid points -> fractional detector pixels)
Sampling principle reference:
High resolution 4581 by 4581 convolved matrix
sampled in boxes around the projected grid points
Interpolation (l,p to lf,pf) principles tested for target:
bi-cubic
linear
nearest
The grid point spacing used is a realistic projection of the regular ground grid on the detector plane.
The ground grid is projected with 748 by 871 points covering the full 509 by 509 detector matrix plane.
EPS-SG VII test-data radiances / LOA

8. Co-registration error Using VII test-data as reference field
Full terrain:
Reference: : High resolution, convolved matrix
sampled at high resolution to lf,pf
Target: High resolution, convolved matrix
sampled at 3MI resolution (509 by 509) and then interpolated from l,p to lf,pf
Bi-cubic / 3MI PSF
Sampling principle reference:
High resolution 4581 by 4581 convolved matrix
sampled in boxes around the projected grid points
Interpolation principles tested for target:
bi-cubic
linear
nearest
The grid point spacing used is a realistic projection of the regular ground grid on the detector plane.
The ground grid is projected covering the full 509 by 509 detector matrix plane.
EPS-SG VII test-data radiances / LOA

9. Co-registration error Residual matrices – 3MI PSF ESA “Best”
Full terrain residuals using 3MI model PSF ESA “Best” :
Reference VS Target
Linear / 3MI PSF
Mean Residual 9.29%
EPS-SG VII test-data radiances / LOA

10. Co-registration error Residual matrices – 3MI PSF ESA “Worst”
Full terrain residuals using 3MI model PSF ESA “Worst” :
Reference VS Target
Linear / 3MI PSF
Mean Residual 8.13%
EPS-SG VII test-data radiances / LOA

11. Co-registration error Deriving co-registration errors – correlation with inhomogeneity
Full terrain residuals using 3MI model PSF “Worst”:
Reference VS Target
Radiance in-homogeneity from VII
Linear / 3MI PSF “Worst”
Mean Residual 8.13 %
EPS-SG VII test-data radiances / LOA

12. Radiance in-homogeneity
Co-registration error Deriving co-registration errors – correlation with inhomogeneity – PSF ESA “Worst”
Full terrain residuals using 3MI model PSF “Worst”:
Reference VS Target
Bi-cubic / 3MI PSF
Mean Residual 8.13 %
Radiance in-homogeneity
from VII
scoreg  a*VIIinhom+ b
EPS-SG VII test-data radiances / LOA

13. Radiance in-homogeneity
Co-registration error Deriving co-registration errors – correlation with inhomogeneity – PSF ESA “Best”
Full terrain residuals using 3MI model PSF “Best”:
Reference VS Target
Bi-cubic / 3MI PSF
Mean Residual 8.13 %
Radiance in-homogeneity
from VII
scoreg  a*VIIinhom+ b
EPS-SG VII test-data radiances / LOA

14. Co-registration error Deriving co-registration errors – correlation with in-homogeneity – focus on inhom>0.5
Full terrain residuals / high frequency focus (in-homogeneity >=0.5)
PSF ESA “Worst”
PSF ESA “Best”

15. Co-registration error Deriving co-registration errors – correlation with in-homogeneity – focus on inhom<0.2
Full terrain residuals / high frequency focus (in-homogeneity <=0.2)
PSF ESA “Worst”
PSF ESA “Best”

16. Sensitivity PSF and co-registration error analysis Study on aliasing impact
Simulated PSF Gauss
with no aliasing
F=fnyq

17. Radiance in-homogeneity
Co-registration error Deriving co-registration errors – correlation with inhomogeneity – PSF “Perfect Gauss”
Full terrain residuals using 3MI model PSF “Perfect Gauss”:
Reference VS Target
Bi-cubic / 3MI PSF
Mean Residual 8.13 %
Radiance in-homogeneity
from VII
scoreg  a*VIIinhom+ b
EPS-SG VII test-data radiances / LOA