CS 184: Computer Graphics and Imaging, Spring 2023

Final Project: Minecraft Path Tracing and Physically Based Renderer Milestone Page

Oren Azad, Omer Sasson, Varun Srivastava, Arthur Pan

Accomplishments So Far

The primary goal of this project is to extend CS184's path tracer to support rendering small minecraft builds and eventually, larger scenes. So far, we've successfuly been able to load in 3D geometry from Minecraft along with it's base texture into the pathtracer. We've also successfully implemented UV mapping and the other bells and whistles needed to use textures in the pathtracer. We used project 3-1 as a base, and decided to use the Open Asset Import library assimp as our tool for importing Minecraft scenes. Refactoring the project to be able to use this new library and the imported geometry has been a massive undertaking so far, and there is still more to do. However, it has been quite promising so far. Additionally, we included stb_image in order to load the textures images.

Currently we use assimp to read in all the vertices and their corresponding textures from an OBJ and MTL file into the scene. From the vertices, we create our triangle primitives that populate the BVH. We are still using the included COLLADA reader for lights and the camera however, but we will be scrapping that in the future. We've also created a new class called Textured Triangle which extends the Primitive class, but holds a texture and samples the texture at the ray-triangle intersection point.

Finally, we also did some work in Blender to create path traced renders of minecraft builds to learn more about how textures work in path tracing and what we might expect. Here is an image we produced in Blender using the Cycles renderer.

Preliminary Results

We are quite happy with our preliminary results, and we think the pathtraced output looks amazing! As you can see, we loaded a small minecraft build into the traditional cornell box, and got a great looking image as a result. In the future, we will be able to use larger scenes as we work on some of the project infrastructure, in particular, using a different format for our 3D scene like FBX or COLLADA with assimp. Further, this scene only uses the base minecraft texture. As stated in our proposal, we plan to include Minecraft's PBR textures as well for an even better looking result.

We also worked a bit on the OpenGL side of the pathtracer to allow us to see the Minecraft textures in the rasterized preview!

Reflection and Updated Roadmap

We have been able to implement much of the important functionality into the pathtracer so far. Still, we must work on the infrastructure to support lights and the camera through one file (rather than a split COLLADA and OBJ file), as well as the PBR effects and textures. As certain issues like importing files has proven to be a larger challenge than expected, we don't persay plan on hitting our stretch goals. However, we are very happy with the progress so far and believe that the final result will be quite nice.

From here the work will mainly be split into two categories:

Project Infrastructure: Working on importing larger scenes and using a more comprehensive file format and importing system.
Physically Based Rendering: Working on using Minecraft's other PBR textures to produce great images with more advanced effects.

We will be working on these side by side in the next two weeks. If all goes well, we will investigate some stretch goals and additional nuance that might be fun to add to the project!

A funny result we encountered while first working on importing scenes from OBJ files.