Google has announced that Seurat, its scene simplification tool for converting complex 3D scenes for VR display on mobile, is now free and open-source. Seurat works based on the assumption that VR is viewed from within a limited region. It takes RGBD images (images with depth information) from within that region and then reconstructs a textured 3D version of the scene with options for the poly-count, texture size, and fill rate.
Find out more about this announcement on the Google Developers blog and download the code and plugins for Unity, Unreal and Maya from GitHub.