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I made some investigation on the trend of this error. The results are shown in error_trend.png. In the figure, "x_loc" indicate the x coordinate in pixels in the local coordinate system of the camera (i.e. the horizontal one), while "x_glob" is the x coordinate in cm in the global coordinate system. Remember that the axises of the local and the global coordinate systems are inverted. Data where gathered for two cameras.
I decided to consider the error linear along both direction and try to apply a correction to the computed global coordinates.The The correction is thus applied is in the form err = a*x_loc*y_loc + b*x_loc + c*y_loc + d. The parameters a, b, c, d are computed by the CPS on start by loading a file where the real global coordinates of four points must be saved. This is the procedure that must be followed to configure this file.
THINGS I WOULD HAVE LIKED TO BE DOCUMENTED
- The car number is on the heatsink on the motherboard hidden under the adhesive paper ring.
- Car circuit model.
- CPS code currently doesn't compute the vehicle heading by checking the line on the cars' symbols. It just checks the previous and the current position to do it.
- How to use Moto.exe.
- One must pay attention whether there is some overlapping area between two adjacent cameras.
NOTES
- The testbed is not completely flat, there are slight slopes. A car that runs on a circle with constants steer and pwm shows low frequency oscillations on its speed (measured with the encoder) because of this.
- Battery status greatly affects the engine performances.
- There was a bug in the CPS code that affected the initial target dectection for cars that were not tracked by computer 0. It's fixed now but old CPS should not be used (at least Kevin's and Leo's).