2D to 3D conversion is the process whereby existing 2D content is converted to 3D. There are a number of different methods that can be employed, though none will produce the same effect as recording in 3D in the first place. There are a number of reasons for this. A key issue is that some information is missing. Try looking at an object in the distance that is partially obscured by one nearby. Close each eye in turn. You'll see that more of the background is visible in one eye than the other. If you only had the view from the more obscured eye, the extra background is missing and would have to be extrapolated (invented) when creating the missing eye view. 3DCombine contains proprietary algorithms for re-creating this missing data, but it's still a guess. Transparent images (glass with partial relfections) pose a particular problem and should be avoided wherever possible. When converting 2D photos to 3D, the only really effective way is to use a depthmap. This is a greyscale image where objects further away are coloured darker than those nearby. It allows the location of objects in the scene to be accurately specified. Computers are still not yet smart enough to determine that automatically from the scene alone. It's also possible to just set the image backwards (depth queueing) so it appears behind the monitor. This can trick the brain in to seeing it as 3D but it isn't really. When it comes to videos, the way that objects move in the scene relative to each other and the camera provide more information about them. The automatic 2D to 3D converted in 3DCombine takes advantage of that to identify objects and their correction location in the scene. It will sometimes make mistakes however which can lead to artefacts in the scene. By far the most effective way of converting videos is to create a depthmap, as when converting photos. This can be time consuming on a frame by frame basis so 3DCombine routines which identify the objects contained by the depthmaps and attempts to track them as they move. This reduces the number of depthmaps needed to one per keyframe. A keyframe is one where the scene changes significantly, such as when the scene cuts or the camera changes to a different viewpoint. In the interactive mode within 3DCombine, the software will detect this automatically and prompt the user for a new depthmap. Follow this link for video tutorials to see 3DCombine's 2D to 3D capabilities.