ACAD NURBS > RHINO and Gen'lly More Robust 3D CAD

From: Jonathan Chertok (
Date: Fri Apr 11 2003 - 00:38:07 EEST


1. Can anyone tell me if there is a special way to get NURBS curves from
ACAD 2000 into Rhino. I have some curves modelled in ACAD, but they seem to
come into Rhino without all the through points.

2. Also, can anyone tell me exactly the limitations of ACAD 2000 are
particularly with respect to 3D and NURBS modelling. My reading tells me
that "Autocad is a Non-Uniform Rational B-Spline (NURBS) modeller and uses
polygon meshing to create 3D surfaces" (ACAD 2000 3D - Matthews). This
sounds pretty good for my uses. What exactly would this not allow you to do
with respect to manufacturing (as opposed to rendering)?

3. I have also run across the statement "Unlike Mechanical Desktop you will
find Autocad is limited as a surface modeller." Can anyone give me a
common-sense understanding as to what Mechanical Desktop (or 3D Studio) can
do for me that Autocad cannot?

4. If there is a ACAD NURBS (or overall NURBS) Guru out there I wouldn't
mind picking their brain about a couple other issues as well.

5. And tangentially (I think) can I go from .stl to IGES relatively easy in
order to get some things machined? Or is this a tricky bunch of business? Is
there a date that this was discussed on RPML, name of person who posted the
question, etc?


I'm a monster on ACAD (and hate to put all that "Masonic Knowledge" aside,
but I would like to step up my 3D Modelling capabilities (like getting
points in space from 3D objects and being able to projectively work with
shapes...) as it relates to my architectural - and other - work. Do I go
with 3D Studio, Mechanical Desktop, Rhino, or look in another direction?
Charles has specifically mentioned Revit and Nemetscheck's Vectorworks
Architect - neither of which I am familiar with...has anyone got a handle on
where I can get more information about the state of the state with respect
to more robust 3D CAD Programs. Speaking of which what does Bentley do for

I suppose I can pick and choose programs depending on what I am doing, but
it would be great to get more of a handle on what does what and what is
coming on strong.



P.S. I will be taking a closer look at Jerry Laiserin's site with respect to
these issues and also would appreciate any suggested links.

Universal Joint Design Build
Full Service Design and Construction

Jonathan Chertok. Principal
Austin Texas [512] 407 9628

Buildings + Digital Manufacturing

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