====== Parameters ======

These parameters control how X4D processes [[other:dsx:dsx_definitions#digitally_reconstructed_radiograph_drr|digitally reconstructed radiograph]] (DRR) and X-Ray images.

^ Parameter ^ Description ^ Default Value ^
| Constant DRR Scaling | This boolean controls whether or not to scale the DRRs for each view by a constant value for all iterations of an optimization. If false, each DRR will be scaled so that its maximum value is equal to the [[Other:DSX:X4D:X-ray_and_DRR_Settings#DRR_Image_Scale|DRR image scale]] value in the [[other:dsx:x4d:x-ray_and_drr_settings|X-Ray and DRR Settings widget]]. If true, a single scale value will be calculated during the first iteration and be used to scale the DRRs in all subsequent iterations. | |
| Eval Bright Threshold | This parameter is used together with //Eval Good Threshold// when performing a detailed evaluation of a bone pose. A pixel is considered “bright” if its intensity in the DRR image is greater than //Eval Bright Threshold//. The range is from 0.0 to 255.0 | The default is 150.0. |
| Eval Good Threshold | This parameter is used together with //Eval Bright Threshold// when performing a detailed evaluation of a bone pose. A pixel's fitness is considered “good” if the difference between the DRR and the X-ray intensities is less than the //Eval Good Threshold//. The range is from 0.0 to 255.0. | The default is 50.0. |
| Frame Envelope 4D Pass1 | This field contains the number of frames near the control point to evaluate during the first pass of 4D optimization. A value of 0 means to evaluate only the frame in each view that is closest to the control point. A value of 3 means to evaluate the closest frame plus the next 3 closest frames on each side of the control point, for a total of seven. | The default value is 1. |
| Frame Envelope 4D Pass2 | This field contains the number of frames near the control point to evaluate during the second pass of 4D optimization. A value of 0 means to evaluate only the frame in each view that is closest to the control point. A value of 3 means to evaluate the closest frame plus the next 3 closest frames on each side of the control point, for a total of seven. | The default value is 3. |
| Frame Spacing 4D Pass1 | This field contains the interval of the reporting times when generating the pose map for the first pass of the 4D optimization algorithm. For the optimization, a pose map is created by evaluating the object’s pose map at every Nth reporting time. | The default value is 5. |
| Frame Spacing 4D Pass2 | This field contains the interval of reporting times when generating the pose map for the second pass of the 4D optimization algorithm. For the optimization, a pose map is created by evaluating the pose map optimized in the first pass at every Nth reporting time. | The default value is 3. |
| Mocap Seed Spacing | This field contains the interval of the reporting time that will be used to generate motion capture seed poses. If the value entered is N then the motion capture data will be evaluated at every Nth reporting time of the X-ray data to generate the motion capture seed pose map. | The default setting is 5. |
| Pose Map Cutoff Frequency | This field contains the low-pass cutoff frequency for smoothing the cubic splines in the POI pose map. If the value is set to 0.0 or less the smoothing is turned off. | The default value is 20.0. |
| Simulated Annealing Temperature | This field contains the initial temperature for the simulated annealing algorithm. The higher the initial temperature, the more slowly the search range will narrow during the optimization. | The default value is 2000. |
| X-ray Opacity | This field contains the opacity of the X-ray images in the 2D and 3D windows. Their opacity should be less than 1.0 so that the DRRs can be seen on top of them. | The default value is 0.5. |