Description

Highlights the state of each camera and identifies any cameras whose calibration may need to be repaired.

During the reconstruction, if the the -computeHealthStats flag is used, Shogun Post calculates and analyzes the data, and then reports on the accuracy of each camera and the state of its calibration. offlineCameraHealthCheck uses this data to report cameras whose calibration may need repair.

For offlineCameraHealthCheck to succeed you MUST use the –computeHealthStats flag during reconstruction.

RMS distance (Root Mean Square distance)

This value reports the distance between the 2D image of the markers on the camera and the 3D reconstructions of those markers projected back to the cameras sensor. The value is reported in the RMS Distance column in the Log window. If the value reported is less than the error threshold, the status light in the 3D Scene view is green, which indicates that the calibration for the camera is good to use. If the value is greater than the error threshold, the status light is red, which indicates that the camera needs to be repaired or recalibrated. This typically happens if the camera has moved since the last calibration.

The threshold for determining good or bad health is set at 1.25 camera sensor pixels, where fewer than 1.25 pixels of error represents good health, and more than 1.25 pixels of error represents bad health.

Proportion unassigned

This value indicates the degree to which data from this camera was used to calculate 3D reconstructions. It is calculated as the proportion of unassigned camera rays from markers that were visible to the camera but not used during reconstruction. Typical values for a good calibration are below 40% (0.4). This value is reported as a percentage in the Proportion Unassigned column in the Log window. If the value reported is less than threshold, the status light in the 3D Scene view is green, which indicates that the calibration for the camera is good to use. If the value reported is greater than threshold, the status light is red, which indicates that the camera calibration is not good to use. This is typically due to one of the following causes:

• The camera calibration is good, but the camera is seeing some reflections. To check this, select the appropriate camera and switch to a Cameras view where you can see the 2D camera data. If you see unwanted reflections, remove the source of the reflections from the capture volume or mask it out.
• The camera calibration is bad, and the markers it is seeing are not being used to create 3D reconstructions at all. This typically happens if the camera has moved since the last calibration. This camera needs to be repaired or recalibrated.

Shogun Post displays two status lights under each camera in the 3D Scene view (use option -showCameraHealth to turn on/off). For both status lights, the color indicates:

• Green: The camera calibration is good and no other issues have been detected.
• Red: There is a potential problem that needs to be reviewed.
• Default color: No data was acquired for that camera to provide status information.

Functional area

Data retrieval

Command syntax

Syntax

Arguments

None

Flags

Return value

string array

The names of the cameras whose calibration may need to be repaired

Examples

// Load a file with a known camera which has moved and reconstruct
reconstruct –currentFrame –computeHealthStats;

// Check cameras' health and print cameras whose calibration may  
// need to be repaired
string $cameras[] = `offlineCameraHealthCheck -RMSThreshold 1.25 -proportionThreshold 0.4 -showCameraHealth on`;
print $cameras;

Additional information

Related commands

• reconstruct