I really regret that I had to present so much at this SWx World, because with that many smart people together in one space I usually walk away with some new ways of thinking about the software that change how I do my job (Robert McDonald, I LOVE that animator tip about manipulating the bounding box to promote clean rotations around products until cameras are available!)... I can't wait to see some of the sessions on multi-bodies and "low-carb part modeling" on the CD to catch up on what I missed, and see if Phil Sluder had any new stuff to get me through day-to-day stuff faster
One technique that has captured my imagination is from Mark Biasottis Advanced Modeling 101 - performing a deform using another body as a deform tool. What has got me thinking is NOT using it as a modeling tool (I do not care so much for investing a lot of time in developing deform-tool-geometry that MAY be allowed into the model IF a fickle feature decides to work and deliver EXACTLY what I desire.. if I did this and it was close but not exact, the CAD and its limitations could drive the final product, which is a poisonous notion)
What has wormed into my brain is the concept of using the deform-with-body tool as a geometry correction and optimization tool. We all do these lofts with various success adding curvature continuity and tangency - or if they are successful, they might not be all that smooth, or have ripples. We also know that every additional face in a model increases the risk of rebuild errors and latter feature failure.
I love the notion of taking surface-push via selected body and using that like vacuum forming a final C2 single-face-skin on top of a close-to-precise mandrill that represents the best currently available model. Where dozens of patches might be necessary to get the geometry nailed using current modeling techniques, we would instead swap in one face, and it would be C2. The accuracy slider would represent the heat of the plastic - the hotter it gets, the tighter it fits, which means you can get more control from your tool body but also more flaws would show through (so your tool better be REALLY good).
On the plane back I started to run through some experiments, and found some good news and some bad news.
The good news is that the success of the feature depends on the same UV direction stuff I have been lecturing about for the last two years - if the UV lines do not 'flow' in the direction that you would sand or sculpt the product, you will not get the shape you really want. So, hooray, I already know what is required of the surface that I apply a tool body to in order to get what I want. The down side is that the UV flow DOES matter - I cannot just create any old surface and hope it works.... it has to have the correct UV direction (you can use face-curves to preview the UV direction if you want to see it) The deform tool *appears* to work by leaving the UV lines *as-is* and only changes them in the direction of the 'push direction' - for instance, if you use the 'TOP' plane as a reference, only the Y value of the UV lines is affected by the deform tool. The accuracy, I think, has something to do with the number of UV lines calculated for the surface, though my evidence is spotty.
The real problem that I see is that the tool body does not seem to effect the very edges of a provided face in my initial tests, so if you want tangency to something nearby, it better already be in the target face. The other significant disappointment is that the tool body does not effect the unseen geometry outside of the boundary of a given face - if you untrim after deform, you will see that the original geometry remains intact, and that the surface goes through crazy s*** to adapt to the tool body but stay in contact to the unseen&unaffected parts of the surface.
In the short term, I was wondering if anyone was interested in sharing experiments via this group to see how we can push this tool to clean up extra faces and create C2 surfaces from non-c2 targets. In the long term, if we find a workaround that is reliable, I think we might get SWx or a third party person to automate the steps that we come up with and provide that magic tool we talked about on the newsgroup a few years back - select a set of faces, punch a button, and have it get replaced by a single face that matches the original (within a tolerance) that is smoother and C2!!!
-Ed