VR for UI Designers: How to Make Skyboxes
In Virtual Reality, user interfaces do not exist in a void but within a 3D environment. When designing user interfaces for VR, UI designers have to stretch our skillset to include environment design, because now the UI is an extension of the environment or vice versa.
It can be a daunting task for traditional UX/UI designers to create a 3D scene because it involves completely different tools and domain knowledge than what we were trained for. But fear not UI designers, there are ways to make an environment for your Virtual Reality UI without the need for 3D models or fancy shader graphs. And that is by creating a 360 image, or skybox.
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Skyboxes 101
You might have seen 360 photos on Facebook or elsewhere. Viewing a 360 photo is like being transported to that location. And a 360 photo is, just like any other photo, a 2-dimensional image. If you know how to edit images (via Photoshop or other means), then you know how to create 360 photos/skyboxes.
You might also have noticed that 360 photos, a.k.a. equirectangular images, are severely distorted. And that both the front and the back of a scene are displayed side-by-side. How does it all work?
An equirectangular image is a type of projection of a 2D image onto a 3D sphere. Imagine printing out a map of the Earth, and then wrapping it around a globe.
In a 3D scene, an equirectagular image can be use as the background image, or skybox, that surrounds the scene. There are other types of skybox projections with their own pros and cons, but for this tutorial we will focus on creating an equirectangular image.
Ways to Make an Equirectangular Image
The simplest way to make an equirectangular image is to take a 360 photo with a camera. If you don’t own a 360 camera then most mobile phones can also do the job. Simply go to the location of your choice, snap a 360 photo, and you are done!
But what if you want to create a futuristic scene, or something else that doesn’t exist altogether?
Well, since equirectangular images are just 2D images, you can try to Photoshop/illustrate one, distortions and all. Here is a guide on how to do just that by a talented individual: Drawing a Spherical Panorama.
I personally do not recommend manually drawing equirectangular images. While it is a fun exercise, it takes an expert illustrator to do a convincing job, and no matter how great of an illustrator you are, you will never be able to reproduce the required distortions perfectly.
The easier way to go is to draw/Photoshop images that make up the six directions and put it into a 3D software, then take a 360 screenshot of that scene.
How to Make Skyboxes From 2D Images
To create a skybox using images alone, you will need Photoshop or equivalent, and a 3D program. In our case we will use Unity.
For this example, I want to create a cartoony environment with clouds and stars against a bright sky. The ground will be a sphere with a cute tree growing out of it.
To start, we make square illustrations of the different objects in the scene with Photoshop, and save them as transparent PNGs.
Next, we create a new 3D project in Unity and import our PNGs. For each illustration we want to create a new Material, set the Shader type to be Unlit/Transparent and assign the PNG as texture.
In our scene, we’ll make a Quad (a square geometry). Go to Create > 3D Object > Quad, and assign the Material to it, by dragging and dropping the Material on top of the Quad. If done correctly, we should see the illustration displayed on the Quad with proper transparency.
Selecting the MainCamera, we need to reposition it at the point of origin (x: 0, y: 0, z: 0). Then we make more Quads of the various objects, place them around the MainCamera, facing it by rotating the Quad to be perpendicular to the camera, and compose our environment in that manner.
Once you have constructed an environment to your liking, you can take a 360 screenshot of it using this Unity plugin: Sky Capture or similar free assets. The result is a perfectly distorted equirectangular image that can be used as a backdrop for your VR applications and prototypes.
While our example is a cartoony skybox, you can also create photorealistic skyboxes using the same technique. The limit is your imagination!
Get a jump start building your VR application with my VR Lobbies: Environments, and Skyboxes Starter Pack, available on the Unity Asset Store.
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