Cubemap and Stereoscopic Images

Written by: Pablo Vezzini, KiSP Technical Services

Cubemap Images

A cubemap is made up of six images which are stitched together to form an environment.  The environment is projected onto the sides of a cube and stored as six separate square textures or as a single texture where all faces are unfolded.  The six squares (textures) form the faces of a cube surrounding the viewer. Each face represents the view along the directions of the world axes. The coordinate system definition varies between software. For example, 3ds Max uses the following co-ordinate system:

+Z Top    
-Z Bottom
+X Right
-X Left
+Y Front
-Y Back

 

If you were to create the six square textures that form the cubemap, you'd get the following 6 images:

     

These are the six images that form the cubemap texture. This cubemap can be used for creating fixed point renders by duplicating the cubemap for the left and right eye. One downside of using this approach is that the cubemap will be monoscopic. This means the at the viewer won't have any sense of depth or perspective when looking at the image.

Stereoscopic images resolve this.

Stereoscopic Images

A stereoscopic image consists of two slightly different sets of images captured for left and right eyes (e.g. from two camera positions). This small offset is what gives the illusion of depth to an image. It provides the brain with spatial information which tricks it into believing and seeing depth in the images. Stereoscopic vision is the normal vision in humans and animals.

To create the Stereoscopic effect for virtual reality, you'll need to render two slightly different cubemaps which will be used for each eye.

Stereoscopic images are made from two different cubemaps for each eye. Therefore, there are a total of 12 unique square textures required. 

The most commonly used packaging for these 12 textures is the Side by Side format. This format consists of two cubemaps in the row format placed next to each other. This is one of the accepted fixed point render formats that can be uploaded to Yulio. 

For more information on the accepted formats, check out our article on Fixed Point Render requirements.

 

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