Plastimatch uses the same internal geometry for the DRR and FDK codes.
The DRR code generates images from a volume, using the following geometry description:
| Inputs | Units | Default Value |
|---|---|---|
| SID | mm | 1630 |
| SAD | mm | 1000 |
| Angle | degrees | 0 |
| Target | 3d position (mm) | 0,0,0 |
| Camera | 3d position (mm) | Computed from Target, Angle and SAD |
| CT Zero | 3d position (vox) | Same as input volume |
| Panel resolution | pixels | 1024 x 768 |
| Panel size | mm | 400 x 300 |
| Window | pixels | Same as resolution |
| NRM | 3d direction | Computed from Target and Camera |
| VUP | 3d direction | Hard coded to (0,0,1) |
| Panel Orientation | 3d direction | Computed from NRM and VUP |
Geometry attributes of a DRR
Intrinsic geometry for DRR computation
The intrinsic geometry is specified by the equation:
![K = \left[
\begin{array}{cccc}
1/\alpha & 0 & 0 & c_i \\
0 & 1 / \beta & 0 & c_j \\
0 & 0 & f & 0
\end{array}
\right]](_images/math/9c7d1c6f362c7d290eec772356c001a5c26432da.png)