How to Export from SketchUp v5 does a superb job of exporting small or large files to 3DS format (see the Marina demo as an example of what can be achieved). Here are a few hints on how  to optimise SketchUp Modelling and Export.   1) Faces Whereas models created and textured in SU will always look acceptable in SU, when you export (3DS) any faces that are "reversed" will be transparent to real-time engines and rendering software.   a) Check faces (via View>Rendering>Monochrome)   If it faces out and is purple, reverse it - don't forget to check the other side! SketchUp Hint:- select any face go to Window > Preferences > Shortcuts > Edit/Item/ReverseFaces  enter Shift+R (or your choice) to set a keyboard shortcut In future, if you see a reversed face select the PushPull tool hover the mouse over the face (don't click - it will be selected automatically) hit Shift+R. Also remember the right-click > Select options, which may speed things up if you have multiple reversed faces.   b) Create outer faces   - for your building facades and inner faces for your interior walls - in other words, like reality!   c) Create a ‘Thickness’   Single-face surfaces, and double-face surfaces which occupy the exact same coordinates, may at best light strangely and at worst be almost invisible when rendered.   In the SU 3DS Export Settings dialog, there are a number of options to export double-sided faces, but the best option is generally to give walls, fences etc a thickness, check both sides "face out" and texture them.   2) Textures When a model is untextured the boundary between adjacent faces can sometimes be unclear. use textures rather than colours when creating the model in SU where appropriate apply different textures to vertical and horizontal faces think carefully about the application/direction/strength of realtime light sources This will help to highlight the geometry and make the model more legible.   3) Units For correct scaling export from SketchUp with Units = metres. (Reality4D camera position and coordinate readouts are currently in metres.)   4) Position If you import a 3DS model with a wide, flat base, you may notice a flickering effect with the ground as you move around the scene. (The effect becomes more obvious the further you move from the model, and is a function of the geometry and maths constantly recalculating the scene, and is common to all realtime renderers.) The renderer needs the two flat faces (the model base and e.g. the ground plane) to differ in their elevation.   In Reality4D:- open the Model Properties Dialog select the model (either in the scene or in the Models List) click the Position Tab raise the model using the Elevation spinbuttons until the flickering disappears (this may be as little as +0.1m) or if the model gets dragged it will automatically align with the ground (it will drop back to 0 elevation). You may prefer to use Y-Offset to achieve a permanent height above the ground. You may also find it advantageous to add extra ‘edges’ which slope very gently away from the main model base outwards and downwards through the ground plane. (See the Example Project house model.)   5) Window Transparency If you would like your building to have transparent windows in Reality4D:...   In SketchUp:- put the building and the windows on separate layers or in groups select the building or solid features, and in the 3DS Export Settings dialog, check "Export only current selection" Export the building then select only the windows/glass and Export again to a separate 3DS file In Reality4D:- open the Model Properties Dialog import the building and the windows as separate models (at the same coordinates) select the window/glass model click the Model Properties  > Vis Light Tab set Alpha to about 30%. In this way you can control the exact degree of transparency of all the windows. See the Mires Beck Demo glass house for an example.   (Please feel free to send us any additional information regarding exporting from this or any other modelling software.)