Throughout the world, more and more research labs are turning to using Virtual Reality for their studies. Why? Virtual Reality provides high ecological validity, repeatability of studies, and lets you design complex scenarios at high cost efficiency. Studies have shown that when participants are exposed to a simulation using a VR display they respond to it almost as if exposed to a real-world scenario (see chart below).
Fig. 1 Ecological Validity of VR as a research tool
Some experimental scenarios would be very difficult to set up and repeat using traditional methods - think of asking a cohort of participants to navigate a busy city environment with unchanged conditions for each participant. Not only is this easy to create in VR, but one can repeat it as many times as needed.
Another major benefit to a VR based experiment, is that you can run multiple participants through a simulation who are located in separate physical spaces, even in different parts of the world!
So what are the things to keep in mind when setting up a Virtual Reality lab, and how does one go about this? Read on to find out.
3. Critical Criteria for Selecting your VR System
Budget - Cost and potential ROI are important considerations when determining the ideal VR system for you.
• Customizability and scalability - A good virtual reality system can be upgraded to
incorporate the latest tech advances while scaling to fit your evolving business needs.
• Use case - What do you want to achieve with the VR system? Different use cases
sometimes require different hardware.
• Footprint - The installation space and storage you must permanently dedicate to your VR setup.
• Quality of experience - Unless a VR system is equipped with high levels of visual refresh rates and fast responses to the movement, participants can experience the environment as lagging and drifting, which can potentially cause motion sickness.
• Responsiveness - How well the VR system responds to your movements and interaction. This responsiveness is typically assessed by the “degrees of freedom” (DoF - up to six) that your VR system delivers. More concretely, does the VR hardware respond to the participant’s three directions of movement - up/down, forward/back, and left/right - in combination with the three directions of head rotation, often termed yaw, pitch, and roll.
These three parts of the VR triangle need to be carefully integrated into a seamless solution to deliver an effective VR experience tailored to your specific use case.
4. Software for Generating VR Environments
At the heart of every VR environment is a software program used to construct and then display the simulated 3D experience, along with a computer processor. The invented worlds of VR can run the gamut from the most simple geometrical block shapes to the most intricately detailed universes that call forth a true sense of awe and wonder. Some VR applications – for example, those delineating the complex worlds of VR games – may take months to develop. Most industry applications don’t need (or want) such elaborate complexity, nor do they have the time to wait for such development. If you and your team are doing the development, important considerations for evaluating such software are:
-Ease of use / easy to learn, even for non-programmers
-Robust open source community libraries of VR code that can accelerate development of simulated environments
-Enhanced “rapid application development” to speed the building of VR environments – often one of the key requirements for industrial applications
-Compatibility with different types of VR system setups and, in particular, with a variety of VR input and output technologies (for example, desktop walkthrough, CAVE, and VR headset). Rendering software should support those integrations hassle-free
First thing to look at is the physical space layout of your room. A few questions to consider:
Is your space better suited for 3D projection onto one or multiple walls, or for a VR headset based system that provides some room to roam around freely?
Will the participant(s) be walking around, standing or sitting down?
Can participants wear VR headsets or not? A 3D Projection system might be the best solution for group settings with no need for VR headsets.
If walking, how much physical space will they need to move around?
Will the participant and the researcher be in the same space or not?
What factors may interfere with getting optimal motion tracking (i.e. interference for motion tracking systems sensitive to infrared light, line-of-sight occlusion, etc.)
Can the area be kept free from obstacles, allowing participants to freely roam around wearing a VR headset?
Will your simulation require networking, allowing remote participants to connect in a simulation?
Will you measure physiological data on participants using biofeedback devices, or even fMRI equipment?
Are there any factors in your designated physical space that may adversely affect research results?
In order to have a functional, safe space in which to maneuver, you will need to block off an open area that is free from any obstacles or clutter. If you are using a camera based motion tracking system that requires free line-of-sight you need to make sure that everywhere the participant walks they are in good view of the cameras. Depending on the particular motion tracking system you choose, different numbers of cameras may be necessary to guarantee optimal coverage of your space. You may have to also account for things that can cause light interference, such as reflective surfaces (windows, glass, etc.) and sources of infrared light (if the system is using infrared motion tracking).
We recommend you consider having a spotter available for the safety of your participants wearing a VR headset. Since the participant will not see the physical boundaries of your lab, it is a good idea to have someone available who can guide them, as well as keep cables out of the way. Most modern VR systems will also provide a virtual boundary system that you can adjust to the size of your physical space.
In considering whether the participant and experimenter should be in the same space or not, weigh these factors: Will it be more important for you to keep an eye on the participant and maintain direct communication, or does your experiment require full separation of participants from those collecting data? Either way, there are many benefits to choosing a separate room and computer for the experimenter, including the ability to record from multiple viewpoints, or to blend physiological data measurements and monitor them in real-time.
As far as wires are concerned, keep in mind devices that need a tethered connection, for example physiological measuring or eye tracking devices. For a non-tethered solution to connect to the rendering computer, you can consider a backpack based PC, such as this one from HP. For cable management you can use drop ceilings, cable runners, or cable pulley systems.
If you are using a projection based VR system (more details on this later), you will need a large, clean -preferably white or light gray - wall as your projection surface. You will also want to be able to manage ambient light interference.
If participants need to be prepared before entering your simulation, for example to attach physiological measuring devices, you may want to plan for a separate adjacent room.
One last factor to consider is that you may need a neutral environment free of biases influencing experimental results, for example an environment that is noticeably hot or cold, noisy, or in other ways affects a participant’s state of mind.
6. Equipment Needed
Next we will go over the hardware that you will need. We will cover the basics first, and then go into a few more advanced setups. For help in acquiring off the shelf, pre-configured Virtual Reality systems contact email@example.com
-3D Wall, 2 sided, or more (especially for education, training, etc)
-Projector or large screen to see the experiment live
-Accessories such as gloves, trackers for body parts
-Speakers and sound
-Physiological measuring sensors
7. VR Headsets
The most common display for a VR system uses a VR headset for the display. There are quite a few to choose from, and factors to consider when looking at which one will be best for your setup. One big separation is whether the headset is connected to a PC or runs standalone as an android device. For the best graphical quality and experience a PC based VR headset is recommended such as Oculus Rift S or HTC VIVE Pro Eye. Android based standalone devices may also prove to be more challenging if you are wishing to run users in the same co-located environment.
Some other factors to consider are resolution, FOV, tracking system, development platforms, price, comfort and whether you wish to have things like eye tracking included. Resolution is consistently increasing in VR headsets, and we have seen the progression from the VFX1 in the 90s at 263x230 per eye resolution to the newer high resolution and wide field of view headsets, such as the 5K XTAL from VRgineers and the Pimax 8KX, as well as pixel density increase to a whopping 3,000 pixels per inch in the microLED panel of the Varjo VR-2 headset.
8. 3D Projection
When one thinks of a Virtual Reality display, the first thing they may think of is a VR Headset (such as the Vive Pro). However, there are many benefits to using a 3D projection setup. If you are going to be using a larger group of individuals a 3D projection based setup would allow for many users to experience an immersive simulation just wearing 3D shutter glasses. For an even more immersive projection experience, you can have the main user’s viewpoint tracked using a system like our PPT tracking that will then update the viewpoint based on where a user is located. For the rest of the users to see the correct perspective, they would have to be positioned fairly close to the user that is being tracked.
A 3D projection system usually consists of a number of projectors that range from business class to cinema grade. Economical solutions use ultra short throw projectors (or lenses) since this allows to front project the image onto the screen or wall without having participants cast shadows. They also require a smaller footprint compared to rear projections setups. Aside from the projectors one or multiple rendering computers that support Quad buffering (i.e. using an Nvidia Quadro card), 3D glasses (and an emitter for certain shutter glasses), an input device (such as a wand or controller) and possibly some kind of tracking system if you want to have the viewpoint updated to the user’s position are typically part of the system.
3D shutter glasses and emitter
Ultra short throw projector
9. VR Headset versus Projection: Side-by-Side Comparison
10. Motion Tracking
There are different tracking systems associated with headsets as well, such as the Valve Index and Vive lighthouse, or the Rift S and Vive Cosmos inside out tracking. Certain optical tracking systems (such as WorldViz’s PPT motion tracking system) can also be attached to upgrade a tracking system if you wish to either increase the positional accuracy or add the ability to track a larger space (such as adding PPT to an Oculus headset).
Here’s a quick rundown of the some of the common tracking systems used in a VR system:
Optical tracking (passive) - Uses reflective markers. Requires many cameras and many markers
Optical tracking (active) - Active markers flash at specific frequencies. Highly accurate. Can track up to 32 markers with less cameras than passive systems.
Magnetic - measures the intensity of a magnetic field in various directions
Inertial Tracking - Uses accelerometers and gyroscopes. Subject to drift. Not accurate for positional tracking
Inside Out Tracking (markerless or with markers) - Cameras or sensors on the headset are used to track position.
For any VR system, you are going to need a good computer. Most gaming computers meet the minimum requirements, but this can also vary depending on whether you are wanting to render very complicated and large models (such as CAD models or large point cloud models). For walking/headset based systems you should try to go with an NVidia RTX or GTX based card, and for projection you would need a Quadro card. Here are some general minimum requirements to shoot for.
Operating system: Windows 10 (requires a 64bit OS)
CPU: Intel™ Core™ i5-4590 equivalent or better
Memory: 4 GB GPU - GTX 1060
Hard drive: 1.8 GB free
As mentioned earlier, you can also look to use a backpack based PC solution, that will allow the users to freely navigate the environment without the constraint of a wire. Although the downside to this is that you are limited with battery life and there are complexities that get introduced (such as having to find a way to stream the display of the backpack PC to an outside computer if you don’t want to have to plug it into a display each time you need to start a simulation).
Oftentimes, labs choose to combine walking VR with a projection system, and one benefit to this is you have a large display in which you can mirror the simulation for outside viewing. You can also mirror the simulation to the rendering computer’s monitor.
12. Input Devices
In order to interact with your virtual simulation users will need some kind of an input device, this could be anything from the typical hand controllers that come with most VR headsets (such as the Vive wands), to a keyboard and mouse if seated, or even using hand gestures with a data glove.
To increase immersion and data analysis information, there are many accessories that can be added (way too many to go into detail here, to discuss this further contact one of our helpful sales people to walk you through the options). Vizard’s vizconnect tool makes it easy to connect to over 100 devices for VR simulations, more information on that here. Some of the more common accessories are:
Sound can be an important, sometimes overlooked, aspect in a virtual simulation hardware setup. While most VR headsets come with headphones, if you are using something like a Projection VR setup with a group of participants it may be more beneficial to have a set of good surround speakers installed. Also, when creating your application, it is good to have the sounds placed in the 3D space appropriately using 3D spatialized audio. For a tutorial on how to use 3D sounds in Vizard, see this page in the documentation.
16. Physiological Measuring Devices
In order to validate a user’s implicit reactions to a simulation, it is highly advisable to use some sort of physiological measuring device. This can be measuring things such as heart rate, skin conductance, EEG, and a host of many other signals. One system that works seamlessly with the Vizard software is Acqknowledge and the Biopac Physiological measuring devices.
17. Eye Tracking
Eye tracking is growing in popularity in VR headsets, and can provide a lot of useful data of how a user is reacting to a simulation. For help with setting up an eye tracking experiment and collecting data on things such as objects of fixation, average view time, heatmaps and much more, Worldviz offers a series of templates you can modify.
18. Quick Tips on Setting up a VR Experiment
-Design with data analysis goals in mind
-If presenting UI or other elements to a user, keep in mind it is most comfortable to view objects at 0.75 to 3.5 meters from eyes
-Capture behavioral data, events, physiological responses, in a meaningful way.
-Try to avoid moving a user’s viewpoint without them controlling it, as this can cause nausea
-Ideally a user should be able to walk naturally and not have to use a controller
-Make sure to optimize your models so that you can keep a consistent frame rate. Lower frame rates and jumps in frame rate consistency can be uncomfortable for the user. You want to shoot for a framerate that matches that of the VR headset (usually around 90 fps).
For help on how to create an experiment using the VR application development engine Vizard, see this tutorial.
Additionally, WorldViz provides custom development services if you have a design in mind, but need help implementing it. Please contact firstname.lastname@example.org for more details.
Setting up a VR lab can bring a huge upgrade in your research. Initially it can be somewhat challenging and take some time, but with the proper setup you will have a much improved environment in which to perform your studies. For further help on how to setup a VR lab and discuss options, contact email@example.com