[cad-linux] Re: 2D versus 3D thoughts
- From: "Jeffrey McGrew" <JMcGrew@xxxxxxxxxxxxxx>
- To: <cad-linux@xxxxxxxxxxxxx>
- Date: Wed, 15 Jan 2003 16:29:55 -0800
For me, it's not 2D vs. 3D. It's line-based vs. object-based.
Qcad is line-based, in that their are lines that you push=20
around. You can put them on layers and such, but beyond that,
the computer doesn't 'know' what the content of the drawing
is or how to manage them. So you wind up having to do that
job; manually updating sections, detail keys, moving a door
when you move a wall, trimming the lines of the wall to make
them close up to each other... In other words, this is the=20
same way that you work in AutoCAD. It's more or less like=20
drafting with a parallel rule and pin-registered Mylar; but=20
you can edit the text a lot easier :)
AutoDesk Revit (IMHO the best CAD package yet made for the=20
Building Industry) is object-based; as is Solid Edge,=20
Pro-engineer, VariCAD, ArchiCAD, and others. These have an=20
inherent advantage over line-based CAD in the same way that=20
object-orientated programming languages do over non-object=20
orientated programming languages. What I mean by this is that,=20
in Revit, the content of the drawings is semi-intelligent, and=20
the computer understands the context within the drawings.=20
Revit can fill out all my detail keys, and update them when=20
I change something. Revit understands that when I call=20
something a chair that it lives on the floor, doesn't show=20
up on the ceiling plan, and is a piece of furniture and will=20
show up on a automatically-generated furniture schedule. And=20
that chair doesn't even need to be drawn in 3D. It's not so=20
much that the data is in 3D, but is more about data-models &=20
databases. Or if I move a wall, the doors (and everything else)=20
that lives in that wall will move too, without my intervention.=20
Or, on the mechanical side, it's the ability to re-size a valve=20
and have the piping that connects to it automatically re-size=20
too; or about being able to have the computer parse the data=20
file and generate automated schedules or order forms for those=20
valves.=20
There is some bleed-over, in that some line-based systems will=20
allow for some level of parametric and object-based items=20
(Architectural Desktop, Mechanical Desktop, Vectorworks) but=20
none of them really work as well as the complete object-based=20
systems; they are a lot like Windows 3.1 in that they are really=20
just 'faking it'. And some of the object-based stuff bleeds over=20
into the 2D realm by allowing you to 'draft' in 2D like before,=20
but it's obvious that it's not it's strongest suit.
And when it comes to graphic quality of the 'drawings' there=20
really isn't an advange of one over the other as far as I can=20
tell so far, for I've seen 2D systems that can't make good=20
looking drawings (AutoCAD and it's AutoCAD-only vector fonts &=20
limited colors) and 3D systems that can make wonderful 2D=20
drawings (Revit's wonderful plans, elevations, and sections=20
drawings that are all dervied from the 3D model).
these 'parametric' systems can be vastly superior to a=20
line-based system when the task at hand is not DRAWING but instead=20
MANAGING INFORMATION. Most of what I do as an Architect is specify=20
what is going to get built/ordered, where it's going to go, and when=20
it's gonna get there. So for me, these object-based systems, that take=20
care of some of the basic drawing needs (like coordinating Detail=20
keys, automatically generating schedules and elevations, and more)=20
can save me a huge amount of time while allowing me to take on jobs=20
I might not have been able to before, like facilities management-=20
something that's all about information tracking.
So I'd look at what you really want to accomplish. For me, AutoCAD=20
hasn't had ANY real value; it was the price of admission to being=20
an Architect because it's what the clients demand that I work with=20
it. I have yet to talk to an Architect that bought AutoCAD because=20
it suited their needs best. If anything, AutoCAD has hindered us as=20
Architects. If you made a AutoCAD-clone that was open source, I=20
would say great! and would try to help out however I could; however=20
I would still have to spend way way too much money on a proprietary=20
system like Revit, because there is no open source alternative at=20
this time. Revit saves enough of my time that it's worth it to me,=20
even if it sucks to be AutoDesk's bitch. :)
But for many people AutoCAD is everything they need and then some.=20
For the professionals, like me, with special needs and the real=20
need for a system to be fast & easy, I'll probably always have to=20
stick with a proprietary system. Architect's don't code, for the=20
most part. I've been doing lots of research, and it looks like=20
making a Open Source version of something like Revit would be well=20
beyond realistic at this current point in time. So instead I'm=20
trying to get it to run under Wine on Mandrake :). Can't give up=20
altogether!
I'm using Open Source where I can, like the GIMP and Open Office=20
and Mozilla and Mandrake 9.0 and more. Those software packages=20
serve basic needs for the majority of computer users, and work=20
very well for me too. But my wife, a graphic designer, uses=20
Photoshop on a Mac because it has the colorspace options she=20
needs to serve HER clients, things that the GIMP doesn't really=20
have. You can argue that the GIMP can do the job to all you want;=20
when my Wife is sending something out to the printer, and if it's=20
wrong, it's a lot of money down a hole & a very angry client- and=20
the people who make Photoshop know printing very very well, and if=20
they say it works, it probably does. She needs a system that easy=20
enough for her to use that she can also trust to be consistent=20
with her special needs.
So I'd look hard at what you really want to do; create a general-
purpose CAD tool (ala QCAD) that's more robust than the current=20
options, or something more like lignumCAD which is a parametric=20
CAD system for furniture designers (and wouldn't work too well=20
for anyone else).
just my 2 cents.
Jeffrey McGrew
Designer
Huntsman Architectural Group
50 California Street, Seventh Floor
San Francisco, California 94111
Telephone: 415.394.1212
Facsimile: 415.394.1222
> -----Original Message-----
> From: Kim Lux [mailto:lux@xxxxxxxxxxxxxxxxxxx]
> Sent: Wednesday, January 15, 2003 3:41 PM
> To: cad-linux@xxxxxxxxxxxxx
> Subject: [cad-linux] 2D versus 3D thoughts
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> I have not spent much time with many of the packages that have been
> discussed here ie Cascade, Varkon, etc. However, rightly or wrongly, I
> have formed the impression that the 3D packages usually have very
> limited 2D drafting capabilities. Is this an accurate impression ? I
> assume it doesn't have to be like that, only that the authors=20
> of the 3D
> packages have put more time and emphasis into the 3D aspect=20
> than the 2D
> aspect ?
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> What is everyone thinking of the 2D QCad package ? It is open source
> and looks fairly well written. Would it be a decent starting point ?=20
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> --=20
> Kim Lux <lux@xxxxxxxxxxxxxxxxxxx>
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