Teaching 3D: Solids versus surfacing/wireframe

[cadprof]

Hello,
This is my first posting since joining. I am an instructor at college level, and have used AutoCAD since 1985. My question is: The cirruculum has us teaching 3D wireframe(elevation & thickness), and surfacing prior to teaching using basic AutoCAD solids commands. I believe we shold start out immediately in solids and then explain to the students about the wireframe and surfacing, allowing more time to refine the solid modeling skills.
I am also doing this not only for myself, but as part of a course I'm currently taking.

Any input would be appreciated.

[Mr T]

Hello,
My question is: The cirruculum has us teaching 3D wireframe(elevation & thickness), and surfacing prior to teaching using basic AutoCAD solids commands. I believe we shold start out immediately in solids and then explain to the students about the wireframe and surfacing, allowing more time to refine the solid modeling skills. I am also doing this not only for myself, but as part of a course I'm currently taking.

I teach sec. school Advanced Higher Graphics. This includes solid/surface modelling and rendering.

Last year I taught all the surface modelling then solid modelling. I have taught solids then surfaces this year. It was a lot more efficient since solids are easier to manipulate and draw in 3d using UCS etc. I did surfaces second, they were easier since 3D awareness of UCS etc is already secure knowledge in the pupils.

Please check my students work at my site www.autocadzone.com

Nick

[robfowler]

I also teach Advanced Higher for the Scottish curriculum and our course notes for this level start off with surface modelling.

However I am into my 3rd year of teaching this now and the students will readily adopt 3D solid modelling techniques. They also enjoy, at an early stage, using Boolean operations / slice / shell etc. on solids which are not possible with surfaces. They are therefore able to gain greater success with modelling at an earlier age than would be possible with surfaces.

Each modelling technique has its own advantages/disadvantages and there are some shapes that are only achievable with surfaces.

However I start 3D solid modelling as early as S3 (13 year olds) and they thoroughly enjoy it - I therefore leave surface modelling until much later once many of the other 3D techniques have been learned.

Every tutor will have their own ideas but the above is what I find has worked for me and has produced excellent student results.

Rob.

[Mr T]

Each modelling technique has its own advantages/disadvantages and there are some shapes that are only achievable with surfaces.
Rob.

What can't be created with solids then ? :?:

Nick

[robfowler]

Some complicated curved shapes such as a computer mouse can only be achieved by using edge defined surfaces.

Granted, the surfaces can then be converted to solids afterwards by using a lisp routine called m2s.lsp but this would be beyond our average AH pupil. Also other shapes produced by the Ruled Surface could not be reproduced using solid modelling in stock Acad.

Rob.

[Mr T]

Rulesurf is really like an extrude along a path, possibly tapered as well.

EDGESURFs are ideal for curvy profiles, but taper face,slice, fillet etc on a solid primitive could create a mouse.

Anyway, I have finished cag mags and I'm about to start rendering and making up layouts, soldraw et al. I have drawn m'persp. and conic sections and my prelim is in a month. How far are you through the course ?

Cheers

Nick

Grangemouth High.

[robfowler]

[Rulesurf is really like an extrude along a path, possibly tapered as well.]

You can do things with Rulesurf which are simply not possible with solid modelling ie. rulesurf from a circle to a square. This command cannot be achieved using stock AutoCAD solid modelling but can with the like of Inventor's Loft command. Although you can extrude along a path you cannot extrude along a path with a taper! Try creating an oblique cone using solid modelling!

I have to disagree about your view on creating a mouse with solid modelling. It may be possible to create a mouse but the likes of Microsoft's Intellimouse would look far more realistically smooth using edge defined surfaces.

It's almost impossible to get teachers to agree about anything eh?

Anyhow, my 3 AH pupils have finished their 3D models and are producing their orthographic drawings from them, sections, scene etc. One lad has done an upright Dyson vacuum cleaner, another has completed a go-kart (all except the engine) and the last of the three has gone down the architectural route and done a tower block. Technical Graphics unit was finished before the end of the year. They have done mag analysis for their DTP and are about to do the thumbnails and visuals before their prelims in 2 weeks time. I think they'll manage to finish the work in time but it's always a bit of a rush at the end!

Ho - hum - the joys of teaching.

Rob.[/quote]

[fuccaro]

I think that AutoCAD is designed to work with solids. Because some solids are difficult to obtain with the tools offered, “they” introduced the surfaces. The surfaces are used only when solids are hard or impossible to obtain. Unfortunately, here is no way (we are talking about AutoCAD) to convert the surfaces to solids, the mathematics used for is different. So I consider the surfaces as an “appendix” good for extreme situations.

[CADTutor]

I have to agree with Fuccaro. Historically, surfaces were the only way to create 3D forms and that was that - we had to use them. I consider that Solids now replace this functionality and you will notice that each recent version of AutoCAD has improved the functionality of solids while surfaces remain untouched. I admit that on occasion I do resort to surfaces but it happens less frequently now.

I teach Digital Design at graduate and post graduate levels. Fortunately, I don't have a prescriptive curriculum to follow and so I can decide for myself what I teach. I have now dropped the teaching of surfaces in AutoCAD but do a lot on solids. I am currently looking at Rhino (serious surface modelling). If AutoCAD surfaces worked like this, I would reconsider the situation but right now, surfaces in AutoCAD are dead!

So, I would condone your approach, cadprof. Start with solids and then backtrack if necessary.