3D Print an Alignment Tool
Step 1: Prepare the Alignment Tool
1.1 If you are using a Vive Focus 3 you can download the Existent alignment tool 3D Model provided to you in STL format from this link and use a 3D printer to print it.
If you don’t own a 3D printer you can use a 3rd party company such as Shapeways that allows you to upload a 3d model and request for the 3d printed item to be delivered to you.
An alignment tool for PICO 4 Enterprise headsets is coming soon!
1.1.1 Print settings vary by printer. Please select the appropriate settings for the printer you will be using. We recommend that you 3D print the tool using 100% infill and supports as well as high precision settings. We also suggest using the following rotation:
1.2 Gather the following materials for assembly:
8mm diameter x 2mm thick N42 Neodymium Magnets - 1Kg Pull or similar pull specification | 4 | ||
M4 Socket Cap Bolt/Screw + Connecting Nuts or Nyloc nuts or Shaft collars
| 4 | ||
Fully threaded M4 Threaded bars | 1 | ||
Polymer Spacer nuts | 4 | ||
15.9 mm (5/8") M4 Sphere Markers
| 5+ | ||
Super glue or adhesive suitable for bonding magnets | 1 |
We recommend using at least five 15.9mm (5/8") M4 sphere markers for optimal results, as these have been thoroughly tested by our team. However, you are welcome to use sphere markers of different sizes, provided you carefully adjust their positions on the tool accordingly.
1.3 Attach the magnets into the designated holes on the alignment tool. Check if the magnets work properly and are the right way around by manually testing magnetism. After that, glue the magnets on the tool.
1.4 Attach one of the marker spheres to the pivot point as shown on the picture below using the double-ended threaded bar or any other tool you can use to make sure it stays 7.95mm above the end of the tool (half size of sphere).
1.5 Take the remaining marker spheres and attach them to the alignment tool. Use the designated holes on the tool for this purpose.
For each sphere besides the pivot sphere, use socket cap bolts and spacers to connect it to the tool. This helps in creating a secure fit.
For the pivot sphere use a fully threaded bar.
Once satisfied with the placement, secure the markers to the alignment tool using attach nuts, nylocs, or shaft collars at the end of each threaded bar, ensuring each marker retains its designated position.
Ensure that the arrangement of the marker spheres forms a precise and stable constellation.
Ensure that the placement of markers won’t make them collide with the VR HMD when it is attached to it. Please see Step 3 below on how to attach and test. Also make sure that the sphere markers won’t be occluded by the headset when attached to it.
When setting up the constellation markers, make sure that their placement does not interfere with the functionality of the alignment tool.
1.5.1 Verify that the cameras can detect and distinguish the markers effectively. For added versatility, consider attaching markers with varying lengths between them, aligning them along the x, y, and z axes to enhance tracking capabilities. Below you can see the constellation we used.
Step 2: Configure Constellation Markers
2.1 Open the motion capture software of your choice ('Motive' for Optitrack or 'Tracker' for Vicon) used for tracking within your project environment.
2.2 Start the process to create a constellation rigid body. Ensure that the placement of markers does not interfere with the headset when attached. You can also use Motive’s tutorials here and here or Vicon’s tutorial here. Make sure you use a standard name for your rigidbody (e.g. 'HMDReference') as we are going to use it later on via the Existent Plugin in Unreal Engine.
2.3 When the rigidbody is created, its pivot point is placed at its geometric centre by default, and its orientation axis will be aligned with the global coordinate axis. You need to modify the pivot point so that it is set to the position of the pivot marker sphere.
Step 3: Attach Alignment Tool to headset
3.1 Remove the Vive Focus 3 Face Mask and attach the alignment tool to it as shown on the pictures below. Ensure the top and bottom magnets are connected and hold in place if necessary. The magnets should make the tool snap in-place.Ensure once again that the sphere markers are not occluded by the headset(besides the pivot sphere)
Step 4: Aligning Head-Mounted Displays (HMDs) for Accurate Tracking
Read the instructions on this page: Aligning HMDs with outside-in systems
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