Action3D Reducer is a great polygon reduction tool that changes the level of detail in real-time and creates both .3ds and .x files.

To reduce a 3d object, Action3D Reducer creates a progressive mesh. Then, you can reduce and increase the number of triangles and vertices displayed by the progressive mesh in real-time using a slider control. Action3D Reducer uses iterative edge contraction for removing or adding triangles and vertices in a 3d object. You can also specify quality constraints that the reduced object must meet. Action3D Reducer will display a progressive mesh with the lowest triangles/vertices count possible which meet the specified constraints. You have total control on the reduction parameters although the default setting works fine. Action3D Reducer is designed to reduce big models and was tested with 3D objects containing up to 300 000 triangles.

It is a user-friendly button driven desktop application. You can create multiple documents and each document is a virtual world in which you can move like in a first-person-shooter game and rotate the 3d objects with your mouse. To better see your 3d objects, you can enable up to 6 directional lights, change the color of the light and of the virtual world background. Action3D Reducer is a multi-threaded application which means that you can do other things like changing the light or moving in the virtual world while reducing an object.

You can load 3d objects from a .3ds and .x file and save them in either file formats. Action3D Reducer can also load the following texture file formats: .bmp, .dds, .dib, .jpg, .png, and .tga.

Not all models can be reduced by a factor of 10 while keeping a decent level of quality. Obviously, it depends on the density of the original model and its geometry. But Action3D Reducer is a real polygon cruncher and you will have a hard time to find a competing product that can reduce further a 3d object reduced with Action3D Reducer without a great loss in quality.