Realis3d is described as 'REALIS3D is a state of the art visualisation package that lets you create stunning real time 3D environments quickly and effortlessly'. There are four alternatives to Realis3d for Windows, Mac, Autodesk Revit and Sketchup. The best alternative is Lumion. It's not free, so if you're looking for a free alternative, you could try Enscape3D or LumenRT.
Designed by architects for architects, veteran visualization studio KA-RA has announced the release of Twinmotion®2, an award winning real-time studio that lets architects and designers create, edit and share interactive 3D models.
Walk through your architectural projects in virtual reality with the Oculus Rift. Download the Enscape Revit plugin and Revit sample projects for free. Enscape is a Realtime Rendering Plugin for Revit. Live link from BIM to virtual walkthrough.