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Position Aiding: HTC Vive

Tutorial: 

 

MVN allows for position aiding with HTC Vive. With the feature, the MVN fusion engine combines the Motion Tracker data from the Motion Capture System (Link or Awinda) and the HTC Vive position tracking to improve the global position.  This can be extended to multiple systems, improving the multi-actor alignment and optimizing the workflow.
This article helps you to set up a recording with HTC Vive Position Aiding.

Before you start, make sure to have:
- Correctly set up your Xsens Motion Capture (Link or Awinda) system: 
- Correctly set up the HTC Vive: HTC Vive Setup Guide

Note: HTC Vive Position Aiding is only effective after HD reprocessing, so the data will not be used in live applications.

 

Required Means

Hardware

Item Version Amount
Xsens Link or Awinda -

1 per actor

Vive Pro SteamVR Base Station (No combination of versions)

1.0 

2, more details: Vive play area

 

2.0 

2-4, depending on room scale (see below). More details: Using more than 2 Base Stations

Vive Tracker (No combination of versions) 1.0 1 per actor
2.0 1 per actor
Tracker strap / mount - 1 per Tracker
Base station mounts / clamps - 1 per Base Station

 

Software
- MVN Animate Pro / Analyze 2020.0
- Steam with SteamVR

 

1. Set up Session

1. Open MVN
2. Start a new Session by clicking the Blank Page icon (or go to File > Start Motion Capture)

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 NOTE: make sure that the system is Ready for all operations. 

 

3. In the Motion Capture Configuration window go to the Position tab. 

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4. Open the 3D position Aiding drop-down menu and select HTC Vive. 

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NOTE: An octagon mceclip12.png will appear on the avatar to indicate the Status and Location of the Vive Tracker:

mceclip12.png: Vive Ready and receiving position data

mceclip13.png: Vive Tracker ready but not receiving position data. Check SteamVR if the Tracker is in the Play Area

mceclip11.png: No Vive Tracker detected: Turn on the Tracker and make sure it is paired in SteamVR

 

5. In the TrackerID drop-down menu, select the Vive Tracker ID to attach to this actor. 

mceclip1.png

NOTE: To check TrackerID, see the HTC Vive Setup Guide

 

6. Select the segment of the body where the tacker will be mounted. 

NOTE: Only one semgent can be chosen per System. In general, the pelvis mounted Vive tracker is used for Positions Aiding. Choose Fore Arm or Lower Leg if the motion capture data requires more position accuracy for that segment.

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NOTE: You also check the hardware status of the Vive Tracker by pressing the Wrench Tool icon in the Motion Capture Configuration window. mceclip25.png

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7. Press Ok

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In the Viewport the avatar and Vive Position data are shown. 

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2. Mount Vive Trackers

1. Mount the Vive tracker on the chosen segment

 

Pelvis

MVN indication

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Vive Tracker Placement: Just above Pelvis Motion Tracker

 mceclip2.png  mceclip3.png

 

Forearm (left and right)

mceclip20.pngmceclip21.png

Vive Tracker Placement: at 1/2 of the forearm (halfway from wrist to elbow) on the outer side of the arm in n-pose.

mceclip8.png

 

Lower Leg (left and right)

mceclip22.pngmceclip23.png

Vive Tracker Placement: at 1/3 of the lower leg (one-third from the ankle to the knee) on the outer side of the arm in n-pose.

 mceclip7.png

 

 

3. Calibration

 1. Follow the regular calibration procedure: 

Link
Awinda

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4. Recording

After calibration, you are ready to record. 
1. Make sure you are in the bounds of the Play Area. 
2. Press record. 

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3. Press Stop Recording to stop the recording. 
4. MVN will create an mvn-file with the Vive data included. However, HTC Vive Position Aiding is only effective after HD reprocessing. Continue to HD-reprocessing. 

mceclip13.png

 

5. HD Reprocess

1. Open a file in MVN with Vive position data included. 
2. Go to the reprocessing window by clicking the gears icon mceclip17.png

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3. Make sure to select Use HTC Vive and select the same segment the Vive Tracker was attached to. 

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4. Press Start and close to Process the file and close this window. 

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After processing the Xsens Fusion engine has combined the MVN Motion Capture data with the Vive position data resulted in Position aided Motion Capture data (.mvn file). This data can be exported like any other .mvn file: Exporting data from MVN

NOTE: with multi-actor sessions, it is still important to still perform an axis reset (in MVN > Tasks > Axis reset or Ctrl + Alt + A) to align the heading of the actors. 

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