Tracker Installation on Straps

Common Tracker Installation Method

Key Points:

1. The fuzzy side of the strap should face the bottom of the tracker.
2. For users with smaller body sizes, if the strap is too long, moving the tracker near the buckle can significantly alleviate this issue.

For waist and chest straps, you need to unbuckle the triangular side first, then install the tracker on the strap, and finally reattach the buckle. See the video below for details.

Complex Tracker Installation Method

[info] Comparison Explanation

Compared to the common method, this process is more complicated and takes more time, but it is more stable, and the force of the strap on the tracker is stronger. The specific method is shown in the video.

For waist and chest straps, when using the complex method, an additional auxiliary strap is needed. See the video below for details.

Quick Release Installation on Straps

In mainland China, quick release is optional (only for users with quick release)

Common Quick Release Installation Method

Key Points

1. The fuzzy side should face the bottom of the tracker.
2. The fuzzy side must be under the quick release, not directly against the tracker. The first image on the left is the correct example, and the corresponding second image is the wrong example.
3. Similarly, for users with smaller body sizes, if the strap is too long, moving the tracker near the buckle can significantly alleviate the issue of the strap being too long. Refer to the tracker installation

For waist and chest straps, you need to unbuckle the triangular side first, then install the quick release. Refer to the tracker installation

Complex Quick Release Installation Method

[info] Comparison Explanation

Compared to the common method, this process is more complicated and takes more time, but it is more stable, and the force of the strap on the tracker is stronger. The specific method is shown in the video.

For the waist and chest straps, you need to first unfasten the buckle on one side of the triangular surface, and then install the quick release, same as the tracker installation

Recommended Strap Lengths for Different Body Parts

These are just recommendations and not absolute. Everyone can adjust flexibly according to their own situation.

Tracker Wearing Modes

• All 15 points
• Upper Body Mode

  Both arms, chest, waist (optional)

• VR Mode 8 points

  6 points on legs, chest, waist

• VR Mode 10 points

  6 points on legs, chest, waist, left upper arm, right upper arm

• VR Mode 6 points

  Compared to VR 8 points, remove the two trackers on the soles, but follow mode must be enabled!!!

• Single Arm Mode

  One arm and corresponding hand, totaling 3 points

• Other Alternative Modes You can replace the nodes on the hands with the shoulders, but the strap binding solution needs to be resolved by yourself. Currently, the official straps are difficult to support shoulder wear.

Specific Body Parts for Trackers

Introduction to Tracker Positioning Principles

Inertial sensor trackers are direction sensors, not position sensors, so any body deformation will change the direction of the virtual skeleton. Our position is calculated based on the direction of each bone in the body and the length of the virtual skeleton, so the software cannot actually perceive the relative position of the nodes worn on the bones.

Recommended Tracker Wearing Positions

Currently, there are no recommended specific positions. Any position, as long as it is worn on the corresponding bone, can be calibrated and used for motion capture. However, the distribution of body types varies from person to person, which will result in different effects in different positions. Therefore, wearing in different positions will have relatively large discrepancies. Here, we only provide wearing guidance and explanations. More needs to be tried by yourself to understand the impact of different positions.

Principle explanation: Trackers are direction sensors, not position sensors, so any body deformation will change the direction of the virtual skeleton. The core principles of wearing are as follows:

• Trackers should be as consistent with the direction of the bones as possible, rather than changing with the body

  Avoid placing trackers in areas prone to body deformation, such as muscles and easily deformable fat areas. For specific impacts, see Example Analysis of Deformation. Although there are also compensation algorithms, it is strongly recommended to try better positions yourself to reduce the impact of body deformation.
• Avoid sensor direction deformation caused by strap pulling, such as wearing non-tight long pants. When sitting down, the crotch will pull the strap, causing severe leg crossing in the virtual character.
• Avoid sensor direction deformation caused by breathing, such as wearing on the chest and belly.
• Avoid sensors hanging in the air on the strap, such as on the waist and chest. If tied at the back and hanging, it can cause the sensor to shake.
• If not performing advanced calibration, it is recommended that the top surfaces of the trackers on the chest, waist, and head be parallel to the front of the body, rather than placed on the side. Both front and back are acceptable.
• Avoid the strap on the sole being rubbed by the ground, as this greatly affects the result. If using a strap on the sole, try to be barefoot and place the strap in the arch of the foot, or when wearing shoes,

  fix the sensor with shoelaces instead of using a strap

  .

[info] Main Points to Adjust and Test

1. Upper leg tracker: For some people, it is better to wear the upper leg tracker about 5~8cm above the knee in the front. For others, it is better to wear it on the sides of the upper leg, in the middle. Be sure to avoid the impact of pants pulling on the strap.
2. Foot tracker: The stability of the foot tracker directly determines the overall tracking quality. Ensure that the foot tracker is not affected by strap pulling. It is recommended to fix it directly with shoelaces. A simple method is to simply loop the tracker onto the shoelaces, as shown in the left image below. A more complex method requires fixing the tracker or quick release to the shoelaces yourself.
3. Waist tracker: It is generally recommended to place the waist tracker at the back of the body (if needed for sleeping, it can be placed at the side front of the body and use advanced calibration). It is highly not recommended to place it on the belly.
4. Waist and chest trackers: If using quick release, it will increase the center of gravity height. Relatively, not using quick release will be more stable. Additionally, using the complex binding method for the strap is more stable.

Simple Wearing Example of Using Shoelaces to Bind the Sole

Example Analysis of Deformation Cases

Since the thigh is relatively easy to be affected, here are some analysis of affected cases for the thigh.

• Special note: The direction of the virtual skeleton is the direction of the sensor. If the sensor is tilted, the virtual skeleton will also tilt.

Taking the front of the upper leg as an example, in the standing and sitting situations, the distribution of the human body will change. In normal standing, assuming there is a 20-degree angle between the tracker and the upper leg, after sitting down, due to the influence of gravity, more body fat or muscle tissue will normally sag, causing the angle to become smaller. This varies from person to person, and the specific impact is shown in the figure below.

Schematic diagram of front wearing affected by crotch pulling

Taking the outer side of the upper leg as an example, after sitting down, due to the compression of the thigh bottom by the seat, it may cause the body tissue to accumulate to both sides, resulting in an increased angle between the sensor and the thigh bone, which can easily lead to crossed legs, as shown in the figure below.

[info] Wide Strap

1. Currently, there are 5CM wide straps sold separately on Taobao. The 5CM wide strap can increase overall stability, especially for large movements. Currently, it is only in the testing phase. You can purchase it at the specified link. For users outside mainland China, please stay tuned.