Science

1. Science Jessica Pipis Dohy Faied Paul Kolesnikoff Brian Taylor Miranda Mesloh David Goluskin

2. Introduction • The purpose of the science subsystem is to take stereoscopic images of clouds in order to create a topographic map of cloud heights. • There will be two camera’s mounted at specific angles on the satellite. • The gathered images will be sent to the flight computer where an algorithm will find matching points. Using these points the images will be overlaid creating a topographic map which will be sent back to CU. • Also included is a description of an algorithm and test plan.

3. Requirements • The Science subsystem shall be designed to meet all of DINO’s science objectives. It will implement a stereoscopic imaging technique in order to measure cloud heights. • Clouds imaged in the visible spectrum • Field of view of 40-55 degrees is needed for cameras. • Cameras will have a resolution of better than 640x480. • Shutter speed of 1/64th of a second or faster • Ample amount of time shall be allotted for the software system to finish processing an image before another image is required • Each of the multiple images used to produce a topographic map of the cloud must contain the same features

4. Requirements • Mass- 0.56 kg on the main satellite • Power- less than 11 Watts on the main satellite • The Science subsystem will operate on 5V and/or 12V lines • All Science subsystem components shall comply with NASA’s safety requirements • There shall be no pressurized vessels in the science subsystem, including the lens of each camera • All components will comply with NASA’s outgassing specifications • Any glass components shall comply with NASA’s regulations • All components shall either be contained or meet NASA’s requirements to be a low-released mass part

5. Block Diagram Camera #1 Camera #2 C&DH USB

6. The Camera • Basic Information • Olympus C 4000 • Has C-mount capabilities • Field of view depends on lens • 4.0 megapixel camera • Has USB port for data output • Maximum resolution of 3200x2400 • Does appear raw data is not available • Has TIFF format • Advanced noise filter • Need to see if this can be disabled • Electric variable shutter speed • 1/1000 to 16 second

7. Needed Flight Preparations • Design interface for camera • USB or Flash with USB • Write software for camera • Make or acquire lens meeting NASA requirements • Design mount for camera • Test

8. Factors influencing camera angle selection Base/height ratio Algorithm matching Illumination Signal to noise ratio Larger camera angles mean smaller ratio Time Movement Camera Angles

9. Base/Height Ratio Error caused by optical system is unchanging Larger ratio decreases relative error Largest camera angle desired Influences Illumination • Differences increase with camera angle • By change in relative position of cloud, satellite, and sun • Time

10. Signal/Noise Ratio Decreases with camera angle Large ratio desired for increased accuracy of determining cloud height from stereo pairs Influences Cloud Movement • Increases with camera angle • Affects algorithm’s ability to successfully match points in stereo pair • Smaller camera angle is preferred

11. Influences • Based on: • Altitude - 425 km • Velocity – 7.65 km/s

12. Used to simulate topography of the ground produced by stereoscopic sensing Influenced by factors above Atmosphere “magnifies” results Simulator

13. Results

14. Optimization of Stereo Pairs • Between 10o and 20o (probably around 15o) • Two camera layout, preferably three • Multiple pictures • Determining along and cross track wind • Large field of view • Multiple layouts of camera • Previous tables and graphs obtained from • Boerner, Anko: The Optimisation of the Stereo Angle of CCD-Line-Scanners,ISPRS Vol. XXXI, Part B1, Commission I, pp. 26-30, Vienna 1996

15. Camera Layout With Nadir

16. Error in Camera Layout 10o Nadir 30o 20o

17. Error in Camera Layout • The angle between two cameras is insignificant in camera layout • Error increases as angle between nadir and a camera increases • Error negatively affects algorithm • Suggests a +/- camera angle better than nadir and forward looking -10o +10o

18. Camera Layout • Third camera preferable to normalize +/- camera views • Can obtain nadir camera view with • Two cameras • Multiple pictures • Large field of view (dependant on number of pictures taken) • Can have lower resolution in vertical direction

19. Example • Given • Two cameras • Field of view of 10o • Time • About 4.88 seconds between pictures • Illumination changes and cloud movement becomes insignificant • Covers nadir and fore/aft views • Angle between fore/aft views of 15o

20. Algorithm Needs Two Images Camera Camera Cloud Cloud Ground Reference Point Ground Reference Point First Satellite Position Second Satellite Position Cloud Cloud Ground Reference Point Ground Reference Point First Cloud Image Second Cloud Image

21. Algorithm Combines Two Images Cloud #1 Cloud #2 Cloud #1 Cloud #2 Ground Reference Points Ground Reference Points First Images are Overlaid Images are Transformed to Align at Ground Level Cloud #1 Cloud #2 • Horizontal Separation Between Matching Point on Images Determines Height • Topo Map of Point Separation Allows Integer Math • Point Matching Algorithm in Progress • Use of Color and Derivative Information Likely Ground Reference Points Images are Shifted Until Features Match

22. DINO Moves in Three Axes Yaw  • ±10° Pointing Accuracy • ±2° Position Knowledge • 90 min Oscillation Period Roll Ψ Direction of Flight Pitch Φ

23. Pointing Error Moves Two Images • Yaw Rotation is Greatest Error • Forward Image has Rotation and Translation with Yaw Error • Field of View Must be Large Enough to Accommodate Motion Cloud #1 Cloud #2 Ground Reference Points No Error Image Pair Cloud #1 Cloud #2 Ground Reference Points Yaw Rotated Image Pair

24. Modeling Motion Errors Forward Camera Correction Yaw Error Model Pitch Error Model Roll Error Model

25. Basic Algorithm Determined Floating Point Math Avoided Topo Map in Pixel Distance Saves Bandwidth Science Algorithm is Under Way • Point Matching needs Work • Finalizing Motion Correction Technique • Pseudo-Code Needed • Testing Needed • Final Write-up Needed • Implementation in Software not started

26. Science Subsystem Test Plan • Camera Operation • a. Set – up: • i. Iris (f-stop) • ii. Shutter Speed • iii. Flash Setting • iv. Focus • v. Picture type (Mode) • b. Acquisition • i. Shutter Command • ii. Accuracy

27. Science Subsystem Test Plan • Algorithm • a. Individual Pictures • i. Find Cloud • ii. Find Features • b. Picture Sets • i. Transform to Same Coordinate • ii. Match Reference Features • iii. Correlate All Features • iv. Generate Contours

28. LEGO Table Test Plan • Flat Surface can be Mounted on Gimbal to Test Picture Angles • Variety of Heights and Configurations can be Tested • Ideal for Illumination Effects and Color Recognition • Check for donation from LEGO

29. Commands and Sensors • Commands from C&DH • Set up cameras • Turn on/off camera #1 • Turn on/off camera #2 • Take a picture • Retrieve pictures • Clear memory • Sensors • Possible Thermistor

30. Parts List • 2 Camera’s - Approx. $499 each • Olympus C4000 4.0 megapixel • USB Cables • PC Board • Multiplexer Components • LEGO table and testing components

31. Decisions Not Yet Made • Camera angle on structure • Time between pictures • Yaw control needed • How many pictures are needed to determine along track wind • What is the time delay between images

32. Issues and Concerns • Camera • Problem • The camera we are currently using doesn’t have software for USB • Solution • We can write our own software for USB or design an interface to the flash card • Determining Camera angles • Depends on algorithm used • Determining when is a good time to take pictures • Determining whether it is a good picture • We can generate topographic maps, but they may be cloudless scenes • Probably will use color information • Time between pictures • Time we have to take pictures vs. time we need to take pictures

33. Questions?