1. Group S3

2. Lab Session 5 Following on from our previous lab session decided to find the relationship between Disparity vs Camera Separation. Measured Disparity at 1m distance from cameras, for various camera separations. Relationship was found to be linear. As following graph shows.

4. Lab Session 5 Next decided to test calibrations we made in previous lab session. Using following experimental setup. Using data calibration for camera separation 0.281m

6. Lab Session 5 Initial measurement was at arbitrary height. (Don`t really know but ~ 0.13m) Distance between X1 and X2 was calculated to be 0.099m. Actual value being 0.195m Height of cameras was adjusted to 0.261m Value of second distance was calculated to be ~ 0.32m Error of ~ 50-60% in each case!

7. Lab Session 6 To round of our efforts we experimentally measured the size of an artificial crater. We aimed to measure length and breadth of the crater. As shown on the schematic shown next. Breadth = Front – Back Length = Left – Right

10. Stereogram of Crater Measured

11. Lab Session 6 Experimental values of Breadth were obtained using two sets of calibration data. That of camera separation of 0.281m and 0.078m. For camera separation of 0.281m breadth of crater ~0.15m! For camera separation of 0.078m breadth of crater ~0.53m! Actual value of breadth = 0.225m. Width of the crater was not calculated. (Discussion regarding these values and those obtained by other members of S3, and errors in my calculations is yet to be undertaken)

12. Main Sources of Error Inability to be position the cameras such that they are both Parallel. Also we did no know or were able to measure that the actual CCD detectors were correctly aligned in the in body of the camera with the lens etc. We did not know the exact location of the lens in each camera. This added to the error of any measurement made. +/- 3cm max. Precise measurement of a common point for disparity measuremnet.

13. Concluding Comments This system is reasonably good for measuring disparity and depth of an object as long there is no deviation in the Y co-ordinate. 2-Dimensions of a simple object with surface in the same plane as that of the imaging cameras can then be found by pixel / depth calibration. With this system it is probably unlikely that the X, Y, Z position of an object can be found without a global coordinate system. Note: The above statements may change after further consideration of data.

14. Quick Considerations For Planetary Lander Stereo-imager On board heater, to maintain lens and CCD, within known operating temperature range. Cameras mounted on a head which can change in angle such that it is in same plane (or normal to) point being measured. Mast mounted optimally at ~1.5m for good field of view. (Close to human height). Calibration target which can be viewed to calibrate for position on planet, chromaticity, reflectivity and pixel calibration. Low power consumption. Etc..