Mitsuba 3 vs Picogen

Mitsuba 3 is a free, open-source, research-oriented system for forward and inverse light-transport simulation. It offers monochrome, RGB, and spectral rendering with optional polarization tracking, and computes derivatives with respect to camera pose, geometry, materials, textures, and volumes. Dr.Jit compiles rendering code for CPUs through LLVM and NVIDIA GPUs through CUDA and OptiX. Python integration supports development of materials, textures, and rendering algorithms, with documentation covering PyTorch interoperability. Installation is recommended through pip and requires Python 3.10 or later. Optional GPU computation requires NVIDIA driver 535 or later; parallel CPU computation optionally requires LLVM 18 or later. The project reports Linux x86_64, macOS aarch64 and x86_64, and Windows x86_64 support. Its plugins cover materials, light sources, and complete rendering algorithms. The Python package includes thirteen variants by default; more require compiling a custom Dr.Jit version with CMake. Tutorials, notebooks, how-to guides, and API and plugin references are provided.

Picogen is a free outdoor ray-tracing system for generating large terrain scenes with realistic illumination across day and night and detailed plant populations. It supports procedural scene work through SSDF userspace scripting and heightfield objects. Implemented rendering choices include Whitted-style rendering and path tracing. Materials include fully diffuse Lambertian and perfect mirror specular types, while Height-Slang programmable materials and shaders support terrain. A sun-sky global setting controls scene lighting, and cameras provide yaw, pitch, and roll controls. Picogen is licensed under GPL version 3 or later and runs on Linux and Windows. Linux downloads include 32-bit and 64-bit packages for Debian, Ubuntu, and similar distributions, plus tarballs. Windows offers an installer and portable zip or 7zip archives. Source code, a no-signup forum, and wiki documentation are available. The roadmap lists several features as unimplemented, including a graphical interface.