Group S3

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.

3
(No Transcript)
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

5
(No Transcript)
6
Lab Session 5

• Initial measurement was at arbitrary height.
  (Dont 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

8
(No Transcript)
9
(No Transcript)
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..

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)