Editor’s Note: In this technical post we explain how Seurat, a developer tool from Google, is able to bring high-end graphics to mobile VR systems.

If students could see almost any place in the world with the high quality graphics of Google Earth VR, it would create new opportunities for exploration and learning. For this to work, it would need to be based on a system that’s accessible and easy to use for schools. Using a new tool called Seurat, we were able to do just that. We recently launched support for Google Earth scenes in Expeditions, which lets millions of students around the world experience some of the most beautiful places on the planet.

Mobile VR is easy to use, but it has less available computing power than PC-based systems. To make Google Earth VR hit the required framerates on mobile VR, we need to use techniques like occlusion culling. Google Earth has one of the largest 3D datasets available today, and we’re constantly updating it with new scans and applying reconstruction algorithms in our data centers. However, the pace of updates makes it challenging to apply recent research advances.

Fortunately, Seurat can help deal with scenes that are heavily occluded. We announced this tool at Google IO, and it’s a solution for high quality graphics on mobile VR:

Seurat is a scene simplification technology that optimizes the geometry and textures in your scene from a defined viewing volume (cube to the left above). It takes layered depth images (RGBA + Depth) as input and generates a textured mesh, targeting a configurable number of triangles and texture size. Having control of triangle count is beneficial for the Google Earth data, where the quality of the vertex data varies between locations. Hitting consistent framerates is important for VR, and the more reliable the scene geometry rendering time is, the easier it gets to organize per-frame budget for other elements, such as menus and overlays. Below is an example of generating Seurat input from Google Earth data.

As seen below, the mesh looks good inside the viewing volume. As soon as we move outside, we can quickly see the effects of the Seurat occlusion optimization. In this example, we used millions of triangles and 1000+ MB of texture data to generate the Seurat input. The output is a 20k triangles mesh (50:1 compression) with 5 MB texture data (200:1 compression).

In current writing, mobile VR only supports 3DoF (rotation only) tracking. 360 degree images, both mono and stereo, have been utilized in this environment with great success.

Seurat is a powerful tool for bringing immersive experiences with high fidelity graphics to mobile VR. Hear what our friends at ILM had to say about it, and if you want to check out these Expeditions with Earth VR imagery for yourself, download the Google Expeditions app on iOS or Android and enjoy them in your Cardboard or Daydream View. Seurat is still in development, but stay tuned for future updates!

While most students are settling back into the classroom, teachers everywhere are thinking about how to keep their lesson plans fresh. The struggle is real, but it’s definitely worth it: students learn better and faster when they’re engaged with the material at hand. That’s one reason why we built Expeditions: it lets teachers take their classrooms on virtual field trips anywhere and get a completely different perspective. So as the school year kicks into high gear, we wanted to share a few updates to Expeditions that might help bring the lessons to life.

First, this week marks the start of the Expeditions AR Pioneer Program. Our team is hitting the road as we visit schools around the U.S. to bring augmented reality to the classroom.

Students will learn about topics like the circulatory system and Ancient Rome together by observing digital objects right in front of them. The program will kick off in Los Angeles, San Diego, Chicago, Austin, and the New York City area, but these are just our first stops. We’ll be traveling across the United States with Expeditions AR throughout this school year, so if you’d like us to visit your school, please let us know by signing up.

We're also releasing five special VR expeditions this week featuring scenes from Earth VR. Earth VR is one of the most popular apps for high-end virtual reality systems, and it lets you explore the world in beautiful detail, but it needs more computing power than a smartphone can handle. But, thanks to a new tool that we announced at Google I/O called Seurat, it’s now possible to experience some of the magic of Earth VR on a mobile device. You can trek to the top of mountains like Mont Blanc or Kilimanjaro, and take a trip to some of the world’s most famous cities, including London, Paris, Tokyo and Hong Kong. Access these new Earth Expeditions right in the app.

Last, we're bringing self-guided Expeditions to iOS (it’s already available on Android). So now, with an iPhone or iPad, anyone can explore anywhere Expeditions take you. It’s also great for guides who want to assign an Expedition for homework, or do a practice run before taking their classroom along. Check out more than 700 Expeditions including tours of universities, virtual career days, and even a trip to the  International Space Station. So grab Expeditions from Google Play or the App Store, and start exploring!