In my workflow I find that even the best SketchUp models need some clean up before they are used for renderings. There are certain things I go over with every SketchUp model before sending it to software like Thea or 3dsMax.
1. Save a copy and rename it so you don’t mess with the original file. Seems logical, but it’s easy to just open and start working without remembering how important this step can be if you later have to return to the original for some reason.
2. Turn things off: Have you ever opened a model and wanted to flip between saved scenes only to sit and wait for the model to fly from one scene to the next? It takes time. And it takes even more time if the shadows are active. Turn off shadows first, then animation (it’s the first tab in Model Info), then styles that have extended lines or profiles. I want a lean, mean, clean model that can keep up to me while i’m cleaning it up and checking it out.
3. Back-faces: The first thing I do to the model is check back faces. Why? Because faces that are reversed will often not render or will render as pure black. So, first click the Monochrome icon or go to the StyleMenu and find it there. This will show the front-facing faces as white and the back-facing faces as blue. If you see blue, you need to reverse those faces so they become white, front-facing faces. You can right click a face and select Reverse Face. But I like to use an awesome plugin by Tomaz called Front Face. You can download it from SketchUcaton.com. This tool will save so much time and headache.
4. Unhide everything and erase: Go to Edit>Unhide>Unhide All. Also go over to the layers and make sure they’re all visible. You could even to show Hidden Geometry under the View menu if you want. The point is, make sure everything in the file is visible. Then erase what you don’t need. You can select things and hit the delete key, use the eraser tool, and even choose to just erase entire layers. Once the file is cleaned up from things with which you don’t need to clog up your render engine, you can move onto the next step.
5.Consolidate Layers: You’ll already have turned on all the layers in the model. To make the file size smaller before rendering I move everything off the remaining layers and put them all onto the default layer. To do this select your layers (try selecting the first layer you want, holding shift then select the final layer you want and the layers between should also all become selected). If there’s anything on the layers to begin with, when you hit the delete key a few options will come up. I choose to move the content of the layers I’m deleting to the default layer.
6. Purge! Purge! Purge! Every layer, style, component, color, and layer you use is saved in the file. If the design is ready to render, it’s ready to be purged. Under Model Info, in the Statistics tab there is a purge unused. But i prefer to use the Purge All plugin by TIG from SketchUcation.com. It’s fast and you can choose what to purge, plus it delves a satisfying report of what was eliminated from your file. This step of purging is what actually reduces the size of your file. Even if you do nothing else, this is a step you should take once you're ready to reduce your file size- it's not uncommon to cut the file size in half!
7. Consolidate Materials: Close behind Purge All is a powerful (and potentially dangerous) plugin called CleunUp3 by thomthom of SketchUcation.com that allows you to consolidate materials. Too often there are multiple versions of the same material in your model. Generally in a rendering engine you want to select a material, like window glass, and edit it once so all the geometry with that material changes universally. With dozens of versions of the same material, this can take a long time; consolidating eliminates that problem. Of course the other thing to look for is that all your window glass, for example, is actually the same material throughout the SketchUp model. The glass material you apply to a window component and the glass material in a component from the Warehouse might be different. And even though they look the same and you intend for them to be the same, they might very well be two separate materials. Take the time to edit the components so they all have the same glass material if that’s what you’ll be wanting once you get the model into your rendering software.
8. Groups and Components: Inevitably there will be changes to the model or at least to materials. If it's a model I've received from a client I go over the model and look at how it’s been constructed. Ideally objects of different materials are in their own groups, and components for similar models have been used. That way if i have to make a quick material change i’m not wasting time making elaborate selections. Too often people don’t know or get lazy and simply model everything as connected geometry so that when you triple-click an object in order to select it, you end up selection the entire model or at least much more than you need. If you see that you have a model like this, beware how long edits may take you.
9. Save down: I like to save my models down to version 8 or 7. This is because some rendering or modeling software can’t read the latest version of SU and you’ll get an error when trying to import it. You may not need to worry about this step at all. But it’s worth noting.
This whole process takes time. It also saves time. If you do your own modeling you can make it part of your modeling process. If you’re getting the model from some one else, it’s worth going over these steps to make the model as streamline as possible before running it through your rendering engine.