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The "framespec.csv" file

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In order to reconstruct the relationship of an x-ray's focal spot to the=
calibration object, a framespec (or calibration specification) file is nee=
ded. The framespec file itself is a set of xyz coordinates describing the l=
ocation of the points in your calibration object relative to a single point=
(the origin). Therefore, each different calibration object has its own, di=
fferent, framespec file.

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Together with the calibration object, the framespec is needed to create =
DLT coefficients and mayaCams, and the framespec file can also be used to <=
a href=3D"/confluence/display/ctx/Checking+and+troubleshooting+the+calibrat=
ion">check your calibration.

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**How to =
create a framespec file**

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1. Number the points on your calibration object and designate an origin =
point and the orientation of the axes relative to this origin.

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- If you=E2=80=99re working with a cube, it=E2=80=99s generally easiest t=
o use one of the corner points as origin and make it #1. You can number the=
rows of points in whatever order you like, but you must be consistent betw=
een the sheets of the cube.

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- The axes need to be RIGHT-HANDED (follow the right-hand rule) and set r=
elative to the origin point.

<=
br class=3D"atl-forced-newline">

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2. Measure the distance (along each axis) between adjacent points--if th=
is information is not already known from building the calibration cube.

=
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- The MATLAB and Maya scripts are set to work in centimeters, so the meas=
urements of the framespec file must also be in centimeters. Here is a=
n example:

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3. Determine the xyz coordinates of the calibration cube points (in cm) =
relative the origin point.

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- Create a spreadsheet (save as a .csv file) with X, Y, and Z column labe=
ls with one row for each calibration cube point. Start with point #1 (the o=
rigin) in the first column and continue with all points in numerical order.=

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