Homework 6: Multiple views alignment

Due date: May 18th, 11:59pm

You are supposed to take a complete set of views of your object and align them using the tool 3dpalign that Dan and Brad wrote. All the information about that software (user interface, how to install it) may be found here .

   For each of the views you must create 2 files, one with the 3D points organized in a rectangular grid (as in Homework 3) and one with all the parameters associated with the view.
Here is a description of the file formats.

    It is extremely important to get accurate calibration results. If you have consistent errors in reconstruction you will find it impossible to align the views.

   It's a good idea to scan in your object with a plane behind it (to help you in the next homework with the volume carving). If you do this, make 2 .range files for each view - in one of the files, remove the points corresponding to the plane. Do the alignment on the .range files that do not contain the plane, and then use the updated .params files with the .range files that do contain the plane for volume carving.

   Also, it is a good idea to clean your data. You would have probably seen in Homework 3 that there are a lot of noisy points, "floating" around your object. Creating the mesh got rid of most of these, since they weren't close to anything. However, since you are not using the mesh for alignment, but the point cloud, these random points might sabotage the process. You should write a Matlab function that displays the point cloud from several viewing angles, asks the user to click on 2 points, and remove all the 3D points that are displayed within the box defined by the 2 clicked points. (you can also edit out the plane behind the object with this function)

What you are supposed to turn in:

• Add to your results web page several screen captures of the aligned cloud points (use "snapshot" on the sgi's). This should be done after multiple iterations of the global alignment function in 3dpalign.

A thumbnail picture for each of the views (still of your page) Pointers to the updated (after alignment) .params files (each of those files should contain a resulting 4x4 matrix). Make sure you understand the format of this rigid body tranformation matrix.