With XR, Your Head is the Camera
January 5, 2024
Spatial Learning Module: This content can be experienced spatially right inside ShapesXR. Open up links and tap Open in VR. Then jump into ShapesXR on your headset and the learning space will open. Play through the Holonotes to hear Paul’s lecture.
When designing a mobile app you can expect that when you put content on the screen, your user will see it. But when designing for spatial mediums the user can be looking anywhere. Your head is the camera, and your field of view is the de facto cursor. The content you want the user to see could be behind them. Not all XR is the same, and each platform needs to be approached in a unique way.
Provide cues to guide user attention
- VR: With a virtual reality display, you can’t predict where someone is going to be looking at any given moment. If you want someone to look at something you’ll need to provide cues for where to look. Spatial audio and edge-of-screen indicators are good cues to guide the user. Rotation and teleportation are options in VR, unlike MR or AR. When designing for VR look for inspiration from best practices in architecture.
- MR: In mixed reality, you see the real world through passthrough cameras. This can’t be moved in the same way as a VR world. This makes positioning the virtual content challenging so that it mixes with the real world while allowing the user to find and see it. You might need to provide cues for the user to move toward the content. Think of this more like interior design than architecture, where you have to fit within the existing architecture of the room.
- AR: Augmented reality glasses like Magic Leap or Hololens overlay a virtual window over the real world. The field of view (FOV) of the display is smaller than typical mixed reality displays. Users viewing an object in AR have less peripheral vision, similar to looking through a scuba or snorkel mask. Because of this reduced FOV, in AR you more often will need to move content with the user as they look away from it. But don’t lock anything directly to the head. This can be uncomfortable.
Design for comfort
The worst thing we can do when designing XR experiences is make our users sick. Simulator sickness comes from when the real world and virtual world move differently. Different users have varying levels of sensitivity. Your safest bet is to never animate the position of the virtual world, but instantly teleport between positions. If this is too restrictive there are a few best practices to enable comfortable movement within the virtual world.
- Let the user grab and move the world with their hands. The act of being in control gives our bodies enough information to help increase comfort.
- Move the camera at a constant rate in a straight line. Comfort decreases when slowing down and speeding up. And don’t think about tilting the camera.
- Do a quick animation when rotating the camera in a circle.
- Google originally discovered that reducing the field of view when moving increases comfort. Most of our movement sensing is in our peripheral vision. So adding blinders
- Lastly, and this is weird, add a virtual nose. This can increase comfort without the user even knowing the nose is there.