Tue, Apr 23, 8:41 AM CDT

Sophisticated Primitives -- Building Models Fast!

Jan 30, 2004 at 12:00 am by AsherD


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Computer 3D artwork has many facets to it such as modeling, texturing, animation, and lighting. Many computer 3D packages will tout the capability to create common objects (like a face) quickly. The creation of a generic 3D object which anybody will recognize, such as an airplane or chair, is relatively easy, but the creation of a very specific object, particularly one that many people recognize and are very familiar with, like the face of Abraham Lincoln, is much more difficult. I will show you a relatively simple technique of creating models by first building precise but simplified constructs out of common shapes which can then be used to expedite the creation of models and can be used in most 3D packages. The first most important step in creating a model is to do some research. Research can range from a ten-minute sketch of your model on a napkin to many days of research in the library or the Internet. You should be looking for views of your subject from all angles, variants of the model that may have existed, color schemes, or other related information. Once you have some references, you may want to do a couple more things, which could also help you. Create a large compilation of images of the model and apply some grids to the images for reference. I sometimes use transparencies with grids printed on them just for this purpose. Sculpting a model from clay can be useful too. And consider purchasing a plastic model kit if one is available. Of course, none of this research or preliminary work is absolutely necessary but it can be a huge help, especially if what you are working on has a lot of details like an ancient sailing ship or a car engine. The next thing is to translate the references and research into the computer. Some applications have the capability to import images as a backdrop to build a model onto. This interface can sometimes be clumsy and difficult to perform. Another technique is to build the model by stacking 'simple primitives' into a simple but precise shape of the final model. If your 3D package also supports deformers, they can be applied to the primitives to improve the primitive final construct. Additionally, using this technique can resolve several issues with your model ahead of time.
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Decisions can sometimes be made ahead of time concerning the steps and level of details the final model needs. For example, you may not need to put in all the rivets on the wings of an airplane. Maybe some of the details can be applied through the texture instead of through more wire frame components. You may also be able to make preliminary decisions on how you plan to construct the final product. Certain main components may need to be built first as the basic reference point and this technique can help with these types of decisions. You can use the primitive model as a prop in your sets for lighting and texturing tests too. If the final product will have many copies of the model, it may be possible to use the primitive as one of the backdrop small versions of the more detailed final model; for example, ants on an anthill could use the detailed models close up and the less detailed models in the distance. Once you have confidence in the simple scaled primitive construct, you can start building the final model over the top of the primitive, which provides a great way to check how the components you are creating fit into the final product. For this reason, it's crucial for the geometry and dimensions of the primitive model be correct so that your line-ups with the final detailed components come out correct.
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This technique is not necessarily limited to mechanical types of models or models which require strict accuracy either. Many organic and other common non-confirmative models can be prototyped in this manner. A skeleton is a good example. No two real skeletons are the same but we, as humans, are very familiar with the shape of a human skeleton. Odds are, the first whack at a skeleton model will significantly benefit from prototyping the major bone components through simple primitives first. While it's relatively easy to go out and download or purchase a human skeleton model, it might be a little more difficult to get one of a platypus and you never know when you are going to need one of those! This technique can help you get there. This issue will probably be more critical for models that have many components that need to fit and scale well with each other, particularly if the model is to be animated. Let's look at the skeleton idea again. Constructing the arm bones, hand bones, and connecting the arm to the rib cage, shoulder bones, etc., will be much easier when you know how long each bone should be ahead of time and how each bone looks beside all the other major components without having to have the whole model completed ahead of time. It's very annoying to be creating a model and realize that some of the major components, which were built early on, are too long or too small. This can lead to many hours of reconstructive surgery on a model and can be rather frustrating.
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Another unusual aspect of using this technique is the reduction of error or the purposeful introduction of perspective for scenes that have unusual camera angles. If you make the mistake of building your precise primitive model using camera views which aren't isometric, it can lead to disappointing results particularly when you move the camera to a new angle. If you get it right the first time, it will always be right. If you are creating something strictly out of your head like a cartoon character or space ship, building something with simple primitives can also be a big help in the creation process. Making lots of versions of a model can lead down paths that may not have been in your original vision. Animating simple constructs can also help in prototyping your plans and for storyboarding. Simple primitives will also render a lot faster so testing should be easier and quicker. The use of simple primitives can go a long way to helping you create complex objects and scenes quickly, easily, and reduce your iterations for a final product. Their uses are practically unlimited and once you get used to building them, you will probably find them fun to play with and cool to create.
Graphic1760.jpgAbout Kixum: Howdy! I'm Kixum, currently the moderator for the Carrara Raydream forum here at Renderosity. I've also been appointed the Amapi forum moderator formally but I'm just a newbie there. In real life, I'm an engineer who hasn't decided yet to quit his day job to become a computer 3D artist. My work here at Renderosity started when I began the Carrara Raydream Resource CD project. That was around October 2001. My life in computer 3D artwork started a long time ago when I purchased the Corel Draw 6 package which contained Corel Dream 3D. As time progressed, Raydream picked up more features, which I followed. Eventually Carrara entered the scene and finally, after a long dry stint, Eovia got it's hands on it and now we have a living/evolving software package that I can manage. Star Wars and Star Trek stuff are clearly two favorite things I like to work on and I've always had a love for playing music. Thirteen years of piano lessons coupled with my bizarre attraction to the Fife keeps our household busy with homemade music. My love of photography continues to grow and I enjoy it more as I go photograph some of the incredible places in the U.S. Everybody has an artistic talent. It just takes the right palette to paint from to truly show it. -Kix
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