Rusty the Junk - 3D model

Being computer nerds, when we bought Rusty the hull, and started considering her eventual layout, the first thing that came to mind was to draw the plans and play with them on a computer.

Initially we transferred the plan and elevation into a 2D drawing package called Cad/Draw by Tommy Software, which, I believe, is sadly no longer available, but the writers have a new product CAD6. For ideas of superstructure, rig and interior, it was a very good start.

Not satisfied with a good thing we had to try for 3D. Initially we used Turbocad, an industry favourite. We successfully created a 3D model, based on the lines from the original plans, and the superstructure etc. that we had already imagined. Design progressed a long way down this path, until we had something that looked as though it would nearly float!

Yet again unsatisfied, we felt that it would be good to have high quality rendering of our 3D model. Rendering is the process of creating a picture of the model. We found that there was a Renderman compliant renderer called BMRT available, completely free! Renderman was the renderer of choice for the major CGI cartoons of the time (Toy Story et al.) It was developed by Pixar who are still world leaders in computer graphics and animation.

In order to make use of this renderer we needed a modeller that worked in and could output the model in NURBS. I am not going to attempt to explain NURBS here, I strongly recommend those interested look it up. At about the same time a product called Rhinoceros, was being publicly beta tested, that means that it is made available to the public in an unfinished form (albeit close to release) in order to get a much broader range of use and feedback than is possible within the confines of the developing company. Rhinoceros did its modelling in NURBS so was perfect for our needs. We became part of the public beta test and when it was first made available bought a copy.

Unfortunately BMRT was removed from the scene by its developer, Larry Gritz, after he joined Pixar. So we have discontinued using that as our renderer of choice and now use 3delight.

The combination of modeller and renderer was a revelation. Had we had the time and enthusiasm, we could comparatively easily have made a film of Rusty sailing across the waves. It enabled us to model the boat in surprising detail, and then look at it from various angles, and with varying colour schemes, different woods etc. etc. If you are going to work on your own boat, house, car or whatever, we strongly recommend a 3D model.

Operation of these tools at a basic level, which is about all we used, is very straightforward. There is quite a large cost in time to set up a complete model, but a useful model can be made very quickly. Then one refines continuously, so the time is swallowed up. We are still using the model to check out furniture etc. before we fabricate and fit it.

The model is useful for more than just dimensions. With the renderer we can get an impression of what items will look like, individually or in context. We can also find information that isn't easily calculated. For example, once we had modelled them, a single instruction found the internal volume of our awkwardly shaped tanks. And went on finding it, as we tweaked the dimensions to get the largest capacity. One caveat, your boat, plane, house etc. will not match your model perfectly (both the fabricators and the modellers are human!) So never build something for your project without checking the dimensions in real life. That said it still provides a very quick and easy check, because it won't be far out.

When items are being fabricated by other people, one can produce a full set of drawings, views of what the finished item should be like, exploded drawings etc. very, very easily. The welder who made our tanks for us, felt they were the best plans he had ever been given. Making a tapered, aerofoil rudder, goes from being a complete nightmare to just quite difficult. Of course, if you make a mistake in your model, the builder will faithfully reproduce it (not always , but usually), and you have no-one to blame but yourselves.

One of the subtle points, which helped us, was the ability to find the view from anywhere, outside or inside the boat. We were doing visibility checks on the inside steering position. We had mounted a virtual camera, where the helms-person's head would be, and checked the view through 360 degrees. Fortunately that was all fine. However, for some reason we decided to look up towards the mast to check the set of the sail, and realised that we had solid wheelhouse roof above our heads. No way to see the main sail without going outside. It was comparatively easy to add a hatch above the helm at that stage.