Reference material is vital when building 3D models for production. If you're recreating something from real life, you want the actual object in your hands so you can examine it, measure it and see it from every angle. When it's not possible to get the actual object, photographs are a great help in making sure your modeled geometry matches as closely as possible.
When you're working on a video game or animated film, the same overall idea holds true. You want as much reference as possible, but this reference will likely come in the form of drawings and paintings. It's likely when you begin modeling on a project that a lot of work has already gone into designing the world you'll be modeling.
Sometimes concepts are created in 3D, but many times they exist as 2D drawings. These drawings can be created quickly and many iterations vetted without even touching the computer. Every studio and project is different, but here are a few things to keep in mind when modeling from reference art.
How much reference will I get?
The amount of reference that you'll get will depend largely on the scale of the project and on the relative importance of the assets. If you're building a secondary prop or set piece, you may only get one drawing from a three-quarters perspective. For more prominently featured sets, you may get a stack of drawings, paintings, and details.
Hero characters may likewise have an exhaustive set of reference material that's already gone through a substantial vetting process. In addition, you may get orthographic drawings of several sides of the same model. This is usually only done with characters.
Should I model directly from reference images?
Most software applications have the ability to import orthographic views into a particular viewport to use as reference when modeling. This can be a great way to block in the shapes and pieces of your model and work out their relationships to one another.
On the other hand, don't rely too much on matching the orthographic drawings exactly. Often the details on each projection may not match up exactly, and the line width of the drawing can cause uncertainty as well. In the end, these images can be a good resource, but you really need to have the ability to match the desired look of a model without having to rely on them.
What if there are no drawings for part of an asset?
In many cases, you may not get drawings covering every angle of an object. When this happens, it's the perfect opportunity for you to exercise your creative freedom. By looking at the visible parts of the model, you should be able to extrapolate the rest.
If the missing detail is important, drawings will sometimes need to be provided, so be sure to communicate with your lead. In some cases, missing content can also be filled in using live sessions with the designer, so be prepared to build and change things on the fly.
What if I have to change things?
Just because a drawing was created and approved, that doesn't mean it'll always look correct when translated into 3D. Sometimes models will need to be tweaked away from the reference for whatever reason, but don't make that call yourself. Let that happen during reviews. Concentrate on getting as close as you can to the artwork and worry about changes as they come along.
So remember, reference is your friend! It cuts out uncertainty when you're trying to finish models before a deadline and helps those models match a designed look. Relish the opportunity to work with great artists, and you'll all make each other look better in the end.
To start putting these tips into practice, keep learning with the Automotive Modeling in Maya tutorial where you'll get to use reference images to focus on recreating an accurate 3D model of a car.