Picogen vs Terragen

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.

Terragen builds, renders, and animates natural environments for landscape visualization, visual effects, and artistic work. It creates procedural and heightfield terrain, can use real-world terrain data, and adds details such as cliffs and overhangs. Its spherical planetary atmosphere model includes volumetric clouds and fog, multiple scattering, and global illumination. The hybrid renderer combines micropolygon rendering and ray tracing, with support for anti-aliasing, motion blur, depth of field, and render elements. Nearly every project parameter can be animated, and image sequences can be rendered through the interface or command line. Terragen imports 3D objects and camera data, exports terrain as heightfields or geometry in formats including TER, EXR, LWO, OBJ, and FBX, and handles camera data in FBX, Nuke CHAN, and Maya MOV formats. It can also generate HDR environments for lighting in other renderers. Windows and macOS are supported, with Linux render-node support. The free edition is for non-commercial use or 30 days of commercial evaluation, with still renders limited to 1280 × 900. Professional subscriptions start at $10 a month.