HW10: Cameras

1. Take some photos that clearly show an object's size changing, but brightness failing to change at various distances. Take some photos that show light reflecting off one object and illuminating another.
2. Take a photo of a calibration grid, and run dotfind and dotfit (on the powerwall in ~olawlor/dev/osl/bin/) on the photo to determine your camera's radial distortion and field of view parameters. Put these values into a file called "p2.txt". Here's how to run dotfind and dotfit:

   ~olawlor/dev/osl/bin/dotfind dscf0001.jpg 100
   # This program will generate a text file giving the dot locations called "pts.txt".
   # 100 is the approximate spacing between dots, in pixels
   xv marked.ppm
   # Make sure the dots line up with the grid
   ~olawlor/dev/osl/bin/dotfit pts.txt 5.0 0.25
   # Fit a function to the grid in "pts.txt", assuming the camera is 5 inches from a 1/4 inch grid.
   # This program will print out the radial distortion and field of view parameters.

3. Take two photos, and knit them together into a more-or-less seamless mosaic inside a photo editor program like the GIMP.  Hint: this is a trapezoidal perspective warp, so the trapezoid tool should help.  A little bit of blending will help hide the brightness discontinuity too.