Tutorial: How to render a 3D CGI background for your green screen VR video

This tutorial will teach you how to create all-new, awesome backgrounds for your VR video content. The instructions come from our talented creator, Zed, who worked with us on the blog post about submitting your own backgrounds. 

Looking to convert your existing CGI animations into VR content? Read our sister tutorial for the full details. 

What do you need to follow this tutorial? 

• Basic knowledge of Blender 3D (free, open-source)
• Basic knowledge of After Effects (Adobe product)
• Project files: download here: 135mb zip

See how CGI background replacement looks in VR: 

View at DeoVR or download the short sample VR180 video (7 secs, 41mb)

Step by step guide to rendering a 3D background scene for VR:

We have prepared a simple 3D scene for this tutorial. Download the project files at the link above. 

To best merge VR video with your 3D background image, you must pay attention to measurements and size. In general, aim to keep to real-life dimensions, for example, a door height should be around 2 metres. 

Add the camera perspective to the scene and try to keep it as accurate as possible. The key elements to keep in mind are the camera angle and the height from the floor. In most cases, while creating the video footage you should keep the camera straight and static - it looks better in VR and won’t cause dizziness. 

Prepare Blender for VR rendering. Set up your camera to be: VR stereo image, with the relevant field of view (FOV) for the footage you want to use. We use: Panoramic, Fisheye Equidistant camera.

Check the FOV of your lens. For example, the Izugar MX200 has a 200mm FOV, while the Canon RF lens has a 190mm FOV.

In Blender render settings, check Stereoscopy. With this option, Blender will render both left and right images.

Render your image. Save this, and open in After Effects. 

Sometimes you need to prepare a few test renders to check how your video matches the 3D render. Use low sample settings - about 20 with denoiser is usually enough at this stage. 

For the final render, use 500-1000 or more - it depends on the scene.

Add your video footage to the After Effects timeline. Below this, put your 3D render.

Now we need to remove the green background from the footage. 

• The Keylight plugin will give great results.
• Adjust the Clip black/white option to better work with your footage.
• You can use the Shrink and Soften option too

Apply masks to your footage if your green screen doesn’t cover the entire camera view. 

You should see your cutout object with the CGI background. Export one frame to check that everything looks good on your VR headset. 

Want to add shadow? Add a Black Solid layer with opacity set to about 50% and a mask to simulate some shadow. This will improve the connection between the video and the background.

That's all! Now you can create your own beautiful worlds for any VR footage you record. Be sure to upload them to DeoVR and share your creations on the DeoVR Facebook page and other social media.