Arion is described as 'is the hybrid-accelerated and physically-based light simulator developed by RandomControl. It inherits all our expertise in light simulation and makes it run on steroids, thanks to our very unique approach to massive CPU+GPU+LAN computation' and is an app in the System & Hardware category. There are more than 25 alternatives to Arion for a variety of platforms, including Windows, Mac, Linux, Autodesk 3ds Max and Sketchup. The best alternative is Adobe Dimension. It's not free, so if you're looking for a free alternative, you could try LuxCoreRender or POV-Ray. Other great apps like Arion are Keyshot (Paid), V-Ray (Paid), appleseed (Free, Open Source) and RenderMan (Free Personal).
Clara.io is a full-featured cloud-based 3D modeling, animation and rendering software tool that runs in your web browser. With Clara.io you can make complex 3D models, create beautiful photorealistic renderings, and share them without installing any software programs.
Pixie is an open source RenderMan renderer for generating photorealistic images. You can compile Pixie on Windows (using Visual Studio 2005), Linux and on OSX (using XCode or unix style configure script).
Thea Render is a state-of-the-art biased/unbiased renderer with a rich set of innovative features, a powerful material system and its own advanced studio, all-in-one. Plugins are available for 3dsMax, Blender, Cinema4D, Rhino, SketchUp and SoftImage.
YafaRay is a free open-source montecarlo raytracing engine released under the LGPL 2.1 license. Raytracing is a rendering technique for generating realistic images by tracing the path of light through a 3D scene.
NOX Renderer is a rendering software based on unbiased methods. The renderer is available as a standalone Windows executable with a plug-in to link it to 3ds Max. A linking script is also available for Blender users.