# Vicon Memo

###### tags: `environment`
[TOC]

d8222104 Chenghong Lu
#### Prepare the System and environment

* (1) Set up video camera
* (Place the target in the center of the camera as much as possible.)

* (2) Adjust environmental brightness.
* Depending on the selected marker size, the smaller it is, the darker the selection.
* (3) Adjustment of setup parameters. 
* Vicon software interface
* Select the sampling frequency you need, other selections are default.
* (4) Masking (physical or software) of false reflection point in cameras.
* Choose to cover a reflective point with a shading tape. Or the software method is available. In the online state, select "Camera" in the browse window, and then select the camera you want to view, and mask the unwanted recognition light spot.
* (5) Adjust suitable sensitivity

* Select the camera you want to adjust, and in "Properties"->"Centroid Fitting", adjust "Threshold" and "Minimum Circularit" until the markers can be clearly seen.

* Note

* Possible problems at this stage
* The camera does not turn on properly（Reboot the system）
* If the marker is not visible in the space, you may need to select "Label" for the reflection point identification mode.
#### Calibration and Set the origin
* (1) Calibration
* On the right toolbar, click the first camera icon, click "Reset" in "Manage Camera Calibration", and then click "Start" in "Calibrate Cameras". Then in the middle of the test site, wave the calibration wand to calibrate the camera until the yellow indicator light flashes slowly to fast flashing, and finally all the camera indicator lights turn green. The system will automatically start the calibration calculation.
* After calculation the image error should be at least light green.
* (2) Set the origin
* place the calibration wand in the field, the right-angle vertex of the calibration wand will be set as the origin. Click "Start"->"Set" in "Set Volume Origin".

* Note
* If the error of calibration is large (error in red), please recalibrate.
* If the software crashes during calibration, please cancel the calibration after opening the software again, otherwise it will keep crashing.

<!-- * And we can verify the calibration effect with a calibration wand. -->
#### Measuring
* Mounting the marker on the measurement object.
* The camera is suspended from the roof, so it can be picked up roughly as a hemisphere.
* To identify a marker point, at least two cameras need to be able to pick up the marker at the same time.

* Marker rigid body
* To consistently identify a rigid body, it is best to have three marker points installed on the object. As much as possible, the number of marker points on different rigid bodies should be different and the distance between the points should be different.
* Operation steps ：Set markers in subjects to establish the relationship between markers. When online, click the third movie icon on the right toolbar, and click "Start". In the experimental field, perform actions. Click "Stop" to complete the original data collection process. In the offline state, click the fifth setting icon in the right toolbar, select "rebuilding" -> click the start icon. (Please do not perform other operations during the calculation process, otherwise the software may crash easily.) Then click "Subjects" in "Resources" to create a new frame. On the right toolbar, click the second Subjects icon, enter the name of the rigid body, and click the target marker on the rigid body in the browse window. After the rigid bodies are set separately, set the connection relationship between the rigid bodies.
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* (2) On the right toolbar, click the fifth setting icon. Calculate and export the collected raw data for the target Subjects.