Suggestions for how to best set up a VR room for VRED.

When using VR, the VR room setup must be done correctly, as it is critical for your enjoyment and safety. We will go through the requirements, understanding the Room feature and safety twins, tracking system recommendations, and finish off with sound.

VR Room Requirements

When using VRED for your VR experience, we require the following:

• The use of multiple HTC Vives or Oculus (via OpenVR) (see Correctly Setting Up the Tracking System for more information)
• A correctly calibrated and aligned room configuration for every VR PC in the room

• The correct VRED room names entered in the Collaboration module

  Note:

  We also recommend you review the VR Requirements.

Setting the Room Parameter

The Room parameter, found in the Collaboration module, is used to let VRED know which VR participants are in the same real-world space. The room name for these participants must match exactly, this includes capitalization, spaces, and any punctuations. VRED takes the Room parameter, syncs and represents the participants within the tracked space, and uses this information for their safety twin.

Correctly Setting Up the Tracking System

There are a number of things, such as device tracking precision and calibration, along with the syncing calibration of all devices inside the VR room and number of people inside the tracking area, that heavily influence tracking system accuracy during a VR experience. Let's take a look at these.

Room-scale Calibration

Since the precision of the room-scale calibration affects the accuracy of the experience, room-scale tracking must be setup correctly and match each of the HMD PCs. Calibration errors could result in avatars and safety twins appearing in the wrong location, general confusion, and risk of collision.

Tracking System Precision

Since VR devices have their own unique tracking system, these tracking systems can differ in precision. We have gotten the best precision with Vive and Oculus (via OpenVR). We have found that when using other systems, the safety twin accuracy was unreliable. Therefore, at the moment, based on the test results below, we feel these should be avoided for VR room scenarios.

Device	High Precision Alignment Error <20 cm	Medium Precision Alignment Error <40 cm	Low Precision Alignment Error <200 cm
HTC Vive	X
Oculus Rift (via OpenVR)	X
Oculus Rift			X
Windows Mixed Reality (via OpenVR)		X

Tracking System Interference

Tracking system interference can occur whenever many participants are within the same tracked area. This can result in controller and VR hand interference, as well as avatars visually snapping or drifting during a session.

Using the Same Type of Device

The VR Room parameter only supports rooms using the same VR devices. This is because with different VR devices, you get different tracking systems, which are a problem. So, if VR Room A is using 3 Oculus Rifts and VR Room B is using a Vive and Vive Pro, each room will be successful. However, if VR Room C has a mix of devices, such as an Oculus and a Vive, the VR Room feature will fail.

Dealing with Sound

When VR room participants connect with remote participants, issues can arise with sound. Therefore, for HMD participants, we recommend noise-canceling headphones. They prevent hearing real-world voices over those in the session. You will be able to communicate with others and not be distracted by outside noise. Any sound distortion caused by voices coming from multiple places will be avoided, as well as any lag in audio.

Understanding the Safety Twin

When multiple participants are in the same real-world space, without some type of safety mechanism in place, collisions can occur. In VRED, we added the safety twin to provide a visual cue to keep you safe and help avoid collisions.

Safety twins are the aqua grid mesh avatars that aligns with the actual avatar as participants enter the room.

They represent the participants' location in the real-world VR room. As participants move away from one another, the safety twins fade, until they disappear.

When teleporting to a new location, your actual avatar moves to the virtual location and the safety twin remains at its physical location. In the following example, the participant teleported a very short distance.

Safety twin positions are representative, not exactly accurate. Since accuracy greatly relies on a correct tracking system setup, we have added a tracking systems section, to help with this.

Adding a Custom Avatar

Here are some guidelines for adding a custom avatar into your VRED collaboration session:

Avatar Body Part Names

Here are the filenames for the avatar body parts.

Part	Filename
Head	Head.osb
Torso	Torso.osb
Billboard	Billboard.osb
Left hand	L_hand_baked.osb
Right hand	R_hand_baked.osb
Tablet	Tablet.osb

These files are loaded from C:\\ProgramData\\Autodesk\\VREDPro-nn.nn\\Data\\Internal\\VR\\Avatar to create avatars and safety twins.

In general, the structure of the original VRED shipped OSB files must be kept, as some nodes must not be deleted nor renamed.

In the following we list the guidelines for materials and geometry.

Guidelines for Materials

At the start of a VR session, each participant is automatically assigned a color. This color can be changed, during the session, with the Collaboration module's Color option. This color is applied to avatar parts with the colored\_part\_mtl material.

Guidelines for Geometry

Part	Node Names to Keep	Note
Hand	R_HandOpen L_HandOpen	This is the default hand pose (or gesture) for the avatar's hand. It is used when no controller buttons are pressed. It is also the only pose for the safety twin. This is one of the poses underneath gesture_switch.
Hand	R_hand_transformation L_hand_transformation	Each of these has two transformation variants: Oculus and OpenVR VRED. These set the OpenVR variant (i.e., the 2nd one) when loading the hand.
Hand	gesture_switch	Switch node containing these poses: picking, pointing, thumb-up, fist, and open hand. This must be named R_HandOpen for the right hand and L_HandOpen for the left.

The Torso

Note that the default torso file shipped with VRED 2019.2 has a translation of Y = -275. This positions the torso in a plausible way below the head.

The Hands

The default avatar hand design shipped with VRED 2019.2 mimics that of normal hands.

Note that for avatar hands:

• no environment variable is considered
• no skinning is applied
• no hit visualization is built nor needed

Summary

VRED assumes these avatar properties:

Avatar height: 1.75 m

Part	Filename	Material for the Unique Color	Orientation	Note
Head	Head.osb	Colored_part_mtl	Looks toward-Z.	Use Plastic or Reflective Plastic for the colored parts.
Torso	Torso.osb	colored_part-mtl	Looks toward -Z. Translated by (0,-275,0)wrt. the head.	Use Plastic or Reflective Plastic for the colored parts.
Billboard	Billboard.osb	n/a	Looks toward -Z. Centered in the origin.	Must be made of Plastic material. The color stripe at the top is rendered as a 2D rectangle.
Left hand	L_hand_baked.osb	colored_part_mtl	The origin is in the base of the wrist.	Must have these nodes: L_hand_transformation, gesture_switch, L_HandOpen.
Right hand	R_hand_baked.osb	colored_part_mtl	The origin is in the base of the wrist.	Must have these nodes: R_hand_transformation, gesture_switch, R_HandOpen.
Tablet	Tablet.osb	colored_part_mtl	Must have these nodes: R_hand_transformation, gesture_switch, R_HandOpen.