appleseed vs Picogen

appleseed is a free, open source rendering engine for animation and visual effects, built around physically based global illumination. It is designed for individuals and small studios and runs on Windows, Linux, and macOS. Rendering methods include unidirectional path tracing, stochastic progressive photon mapping, light tracing, progressive and interactive rendering, and spectral rendering. For shading, it supports Open Shading Language and on-the-fly shader compilation. Production tools include motion blur, AOVs, Cryptomatte, adaptive sampling, denoising, and resumable render checkpoints. Native integrations are listed for Autodesk Maya, Autodesk 3ds Max, Blender, and Gaffer. It works with OBJ geometry and image formats including OpenEXR, TIFF, HDR, PNG, JPEG, and PSD. Developers can use C++ and Python APIs or extend the engine with external C++ plugins. The listed plan costs nothing and is under the MIT license. The download page lists version 2.1.0-beta, released September 21, 2019.

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.