Comet project

Jean-Yves Bouguet and Andrew Edie Johnson

This document regroups some information regarding the comet project with JPL (the data are not available any more).

Oct 27th, 1997:

The 3D range data is available in the file c135.range.
This file consists of a list of 3 values Xr, Yr and Zr corresponding to the coordinates of the points on the rock (subscript r stands for "range").

The additional file c135.params provides the necessary parameters to compute the coordinates of the points in the camera reference frame (Xc,Yc,Zc) and then project those points on the image plane.

Here is the recipe for projection:

  1. Retrieve the coordinates in the camera reference frame Xc, Yc and Zc:

    The vector trc is defined in the c135.params file as: trc -1.08349318 -0.13863203 110.55296165
    Call the three components of that vector trc_x (=-1.08349318 ), trc_y (=-0.13863203) and trc_z (=110.55296165). The 3D coordinates of the points in the camera frame are then:

    Xc = Xr + trc_x
    Yc = Yr+ trc_y
    Zc = Zr+ trc_z

  2. Project the points on the unit focal plane (x,y)

    x = Xc/Zc
    y = Yc/Zc

  3. Include the lens radial distortion (xd,yd)

    xd = (1 + kcam * (x^2 + y^2)) * x
    yd = (1 + kcam * (x^2 + y^2)) * y

    The parameter kcam (=-0.53855707) is specified in the c135.params file.

  4. Convert in pixel units (xp,yp)

    xp = fxcam * xd + cxcam
    yp = fycam * yd + cycam

    The focal lengths fxcam (=2686.22007742) and fycam (=2567.14622276) as well as the coordinates of the optical center cxcam (=319.5) and cycam (=239.5) are provided in the parameter file as well.

    xp and yp are the pixel coordinates of the rock points. The range of values on the axes are respectively [0 639] (for x, horizontal axis) and [0 479] (for y, vertical axis). The origin (0,0) is the upper left corner of the image.

    In order to check the result, download the test image: c135.ras

Oct 30th, 1997:

Two other data sets: c180.range, c180.params, c180.ras

Dec. 7th, 1997:

We scanned the new comet at 72 different views (5 degrees apert). I give here the first 19 scan data (from angle 000 to angle 090). The naming convention remains the same as before. Due to lack to disk space, I had to gzipped all the files. Here are the files:

Remains to be done:

Dec. 16th, 1997:

The range data for the remaining views (from 95 to 355): comet_095_355.tar.

The images of the comet under 6 lighting directions are available online, together with the results on the lighting directions computations. In addition, you can retrieve the range data for the first comet position.

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