90 Yaw manoeuvre Status QWG 28/04/2016

Transcription

1 90 Yaw manoeuvre Status QWG 28/04/2016

2 Outline Why performing 90 yaw How? Preliminary results 05/10/2016 2

3 Why 05/10/2016 3

4 Why performing 90 yaw manoeuvre?» Pushbroom sensors contain thousands of detectors, each having a unique radiometric response, which will inevitably lead to streaking and banding» A relative radiometric correction must be performed to eliminate pixel-topixel non-uniformities in the raw data» 90-degree yaw maneuver is performed over an invariant site» Each pixel sees the same target 05/10/2016 4

5 Why performing 90 yaw manoeuvre? Example Aaron Gerace, John Schott, Michael Gartley and Matthew Montanaro (2014) 2An Analysis of the Side Slither On-Orbit Calibration Technique Using the DIRSIG Model, Remote Sens. 2014, 6, ; doi: /rs /10/2016 5

6 Why performing 90 yaw manoeuvre? Overlap region 6 05/10/2016 6

7 WHY PERFORMING 90 YAW MANOEUVRE? Commissioning improvements to the pre-flight equalisation parameters But, still some remaining uniformities both at the edges and the middle of the detectors (visible if stretched over uniform areas) 7 05/10/2016 7

8 Why performing 90 yaw manoeuvre? PROBA-V TOA reflectance measurements over desert sites are compared against OSCAR model simulations. The comparison is done on a pixel/column averaged basis for non-projected data instead of using ROI averaged data and this for the full SWIR strip. For each valid SWIR strip we obtain : ΔA SWIR i = ρ SWIR,ProbaV TOA,i ρ SWIR,model TOA,i with i the pixel number Next, the results are normalized by the average value over the FOV : Āi, norm SWIR = Āi SWIR avg Āi SWIR 8 05/10/2016 8

9 WHY PERFORMING 90 YAW MANOEUVRE? Detector nonuniformity 9 Exact quantification difficult due to scene nonuniformities! Detector nonuniformity 05/10/2016 9

10 Why performing 90 yaw manoeuvre? Nominal mode acquisation Scanline 05/10/

11 90 yaw acquisation (without yaw steering) 90 yaw acquisation (with yaw steering) Scanline 1 Scanline 2 Scanline 1 Scanline 2 Scanline 3 Scanline 3 05/10/

12 Why performing 90 yaw manoeuvre? What is expected to be seen in the image Same target on ground imaged by all the linear array detectors 05/10/

13 How 05/10/

14 How? (Study)» Good collaboration between : User segment (VITO) Space segment (Qinetiq) Ground segment (Redu)» Feasability study performed by Qinetiq and VITO» Star tracker blinding study (-90 or 90 configuration)» Region of interest (size, coverage, location)» Acquisition s opportunities PROBA-V operation guidelines for calibration with 90 yaw rotation document (Ref.: PVOPS-TN QS, Iss.: C, Rev.: 0, Date: 05/04/2016) 05/10/

15 How? (Area) 05/10/

16 How? (Area) 90 yaw acquisation (without 2.9 roll) 90 yaw acquisation (with 2.9 roll) 05/10/

17 How? (timeline) The following timings for the calibration request: Calibration window start time: T09:52:48.500UTC (660s margin) Extended zone entry time (no yaw offset): T10:03:48.500UTC Slew manoeuvre initiation time: T10:04:48.500UTC (60s margin) Original zone entry time (with yaw offset): T10:14:48.500UTC Original zone exit time (with yaw offset): Extended zone exit time (no yaw offset): Calibration window stop time: T10:20:40.500UTC T10:22:42.500UTC T10:33:42.500UTC (660s margin) 05/10/

18 How? (animation) 05/10/

19 How? (coverage) 05/10/

20 Preliminary results 05/10/

21 Preprocessing L1B EXTRACT DN LAT LON SZA SensorModel Resize geo/sza Convert TOA RAD LAT(full) LON(full) SZA(full) Reflectance Pixel Selection 05/10/

22 Pixel selection 05/10/

23 Results : CENTER SWIR2 05/10/

24 Results : CENTER SWIR2 compare 05/10/

25 Results : RIGHT SWIR3 05/10/

26 Results : Geometry RIGHT SWIR3 05/10/

27 Result : Uniformity RIGHT SWIR3 05/10/

28 Result : RIGHT SWIR3 05/10/

29 Result : RIGHT SWIR3 : compare libya4 05/10/

30 Conclusion» Yaw-manoeuvre successfully executed» Data pre-processed successfully for all cameras» Niger1 site uniformity must be investigated for every strip» Pixel to pixel profiles to be investigated» Are features in the profiles due to interpixel or surface?» Improvement? Yes = apply to ICP» VNIR strips still TBD 05/10/