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Calibration Pane is used for calibrating the mocap system through the calibration wanding process. This page provides descriptions on the fields and settings included on the calibration pane. Read through the Calibration workflow page to learn about the calibration process in detail.
In Motive, the Calibration pane can be accessed under the View tab or by clicking icon on the main toolbar.
This blocks all pixels that are above the set threshold. By default the threshold is set to 200 but this can be changed by the user in the cameras pane. Pixels in a camera image will have a grayscale value between 0 and 255 inclusively. If the default threshold is used, a pixel that is above 200 will be blocked along with the surrounding pixels.
This feature is a quick way to block data that is not needed and can be used in tandem with manual masking. ↑
This will start recording wand samples. After masking the cameras, press the start wanding button to begin your wand wave. ↑
This will stop wand acquisition and the calibration solver. ↑
Calibration Wands:
Wands come in 250, 400 and 500 mm sizes. Custom wands can also be used. A 250 mm wand should be used for smaller volumes or for systems that have cameras with lenses that have larger focal lengths. The reason being that the cameras will not be able to see all 3 markers on a 500 mm wand if the wand is close to the camera or the camera has a very narrow view angle due to it's lens type. If your camera's are not collecting wand samples while wanding, you may need to use a shorter wand. A 250 mm wand is good to use in most small to medium volumes. When making a calibration wand, understand that the system accuracy will be tied directly to the accuracy at which the wand is constructed. A poorly measure wand will result in poor calibration results. To make a wand all that is needed is 3 markers at set distances in a line.
Initiates the calibration solver. Press this button after collecting enough wand samples. ↑
Applies the calibration results to the cameras. Once pressed, this button will bring up a calibration result box. If the calibration result is satisfactory, press Apply. After you save the wanding the camera calibration pane will switch over to the Ground Plane tab so you can set the global origin. ↑
While wanding the bottom part of the Camera Calibration Pane will show a table of the number of samples collected for each camera in the system. The samples will increase as the wand is waved in the capture volume.
The calibration results will show in the Calibration Engine portion of the Calibration pane. The elapsed time of the calibration solver is shown at the bottom of the list. If no calibration is being processed this area will remain blank. However, when a wanding or a calibration solver is underway, this field will be populated with a table showing the live results of the solution. The components of that table are described below.
As the calibration proceeds through the various phases of the solution you may notice the results slowing when a phases is finishing. Let the calibration finish all phases of the calibration. Once the solver converges on an appropriate solution, press the Apply Result button to apply the solution to the cameras. If you are unsatisfied with the results, hit reset near the top of the pane to cancel the results.
Set the location of the global origin. Use an 'L' Frame or 3 markers in the shape of an 'L'. If only 3 markers are seen by the cameras, you can simply press 'Set Ground Plane'. If more markers are in view then you can select the 3 markers you want to use in the 3D viewport and then press 'Set Ground Plane'.
Motive 1.6 and earlier : L-Frame long (marked Z) "leg" interpreted as -Z, L-Frame short (unlabeled) leg interpreted as +X Motive 1.7 : L-Frame long (marked Z) "leg" interpreted as +Z, L-Frame short (unlabeled) leg interpreted as -X
In this section you can assign the Vertical Offset value. The Vertical Offset (mm) is the difference in height (y-direction) between the L frame vertex marker and the actual ground plane. Use positive values to set the global origin below the 3 marker vertex and negative values to set the global origin above the 3 marker vertex. Motive will recognize calibration squares, unless custom designed, and will ask to correct the offset value before the calibration process. However, the global origin is arbitrary and can be placed anywhere the user desires. ↑
The Ground Plane Refinement feature can be used to refine the ground plane. You can select multiple reconstructions and use the corresponding 3D points to level the ground plane. This refinement feature assumes that the selected markers are all placed on the ground with a given vertical offset (mm) between the marker centroids to the ground surface, and then they use the selected samples to refine the ground plane.
Especially in large-scale volumes where the floor is not uniform, defining a ground plane using the calibration square may not be sufficient because it would be referencing just a local part of the volume. For such cases, this feature allows users to further refine the ground plane.
For example, you can evenly spread out 4 or more spherical markers throughout the floor. Specify the marker centroid to ground vertical offset distance, which would be the radius of the marker in this case. Then press the Ground Refinement button. This will change the vertical location of the floor, ensuring all of the markers are above the floor. ↑
The Volume Translation modifies the global origin after it has been set.
Simply enter the amounts you want to translate the origin in the X, Y and/or Z direction and press the Apply Translation button. There is no limit to the number of translations that can be applied and there is no memory once a translation is applied. To revert a translation, simply translate the origin be an equivalent amount in the opposite direction. If there is existing 3D data in the Take, you will need to reconstruct a new set of 3D data from recorded 2D data after the translation has been applied.↑
The Volume Rotation is use to apply a rotational offset to the current global origin. If there is existing 3D data in the Take, you will need to reconstruct a new set of 3D data from recorded 2D data after the rotation has been applied.↑
