3D drawing size and efficiency (AutoCAD)

[CHE]

Hello again,

 

This time my question is how can a 3d drawing size be improved in AutoCAD. I have been modeling an Ucranian church for the last 3 months at work. We are planning to use the model as an interactive way of designing the new elevator expansion area.

I have been using solids to model the church, which is almost done (bare model without textures).

The size of my file is around 45 MB. So I was wondering if anybody knows a way to improve space and efficiency when modeling with solids in AutoCAD. Thanks again.

 

[Guest ghraben]

OH DEAR LORD!!! a 45mb acad model?!?

 

just based on the size of the model, i'd say you have an excessive amount of geometry in your model. my guess is that a large portion of the smaller details that you have modeled could be effectively reproduced with materials and mapping rather than building them in geometry.

 

you will definately have to slim the model down if you want to do anything "interactive" with it like vrml.

 

another suggestion is to seperate the model into 2 or more files: the "background" model and a "focus" model. rip the elevator expansion area (or whatever you are mainly concerned with changing) out and save as a seperate file. then you won't have the overhead of all the extraneous geometry. you can always xref your focus model into your background model for presentation drawings, etc.

[CHE]

Thanks ghraben,

 

One solution:

 

1.- Export the model to an ACIS (.sat) file and then insert it back (ACIS file) into a new CAD drawing. Save it and set up the layers. This process reduced the model's size to 22 MB.

 

2.- Break the model into 4 pieces (4 drawings). (like you said).

 

3.- Xref them all into a single drawing (background drawing) for future design process.

 

It seems to work well so far. I'll try to replace as many details as I can with textures (I have to learn a little bit more about mapping in CAD ) Thanks a lot.

 

[ May 03, 2002, 01:15 PM: Message edited by: CHE ]

[Guest ghraben]

you're rendering in acad too? let me add another suggestion then: do your texturing, lighting, and rendering in another package. in my opinion, it's not worth it to try to get professional results from autocad - that's not what it was designed for. another package will give you much more control and provide a better looking result.

[Scott Baumberger]

One approach (and it may not be relevant here) is to use 3DSOUT to convert the model to surfaces. Obviously, if you need to keep the model in solids for boolean operations then this won't apply, but I can get as much as 90% reduction in file size if I convert a solid model to surfaces. Once I'm finished with the solids modeling and I know I won't need to change anything, I'll go ahead and 3DSOUT and then 3DSIN back in. It's a good idea to save the solid pieces as a backup just in case, but this method will significantly improve the performance within AutoCAD.

I also model in AutoCAD, but I use several different rendering packages and am constantly exporting 3DS files. A key factor in the quality of 3DS files exported from AutoCAD is the FACETRES variable - play with different settings to get the right amount of detail in your curved solids.

Has anyone else tried this method and had any problems with 3DS files? I usually get pretty good results as-is - the only problem that I've found is that in 3D Studio (MAX or VIZ) you pretty much have to force 2-sided rendering, which adds to the rendering time. I'd be curious to know if anyone else has tried this approach. Hope that's helpful !

[ZepSOFD]

Scott,

The problem you are having with normals in MAX/VIZ has to do with the 3DS exporter in ACAD. If you take a solids/ADT object model with no 3DS translation at all and use the .dwg importer in MAX/VIZ the model will generally import with the normals aligned properly. Also when you use the .dwg importer Do Not check "Unify Normals", which is the reason, I think, that the 3DS exporter in ACAD does not work well because it tries to unify the normals as part of the export process.

 

Give it a try if you don't like it you can always go back to what you are comfortable with.

 

tom

[PI]

i suggest surface modelling. it takes a little bit of time to get used to it but worth the time.. especially in lightscape.

 

tip: preset thickness of line ... type th and then the thickness..good luck

[HeDaCoM]

hi CHE. keep it the good work I've seen a 200Mb Solids acad drawing and it is not a problem. importing in VIZ converts it to surfaces. don't worry about the size of the DWG. and 45 Mb is not very huge. I would like to see the model a tip for not increasing the size is using blocks for repeated parts.

[CHE]

Thanks Hector and PI for the comments. Hector, I'll show you the model, it's the Ukranian church I have been talking about all over this forum. The church is the biggest 3D model I have done until now.(Interior/Exteriors).

Btw, I'm starting to think that 3d faces and surfaces are the way to go for non-complex models. You can always use both techniques

 

[ July 12, 2002, 11:50 AM: Message edited by: CHE ]

[Guest mwaychoff]

good stuff regarding the "Unify Normals" stuff, thanks.

 

going back to the original acad file question for a moment . . .

 

_purge & _audit

we are assuming you have basic file maintenance of 3 "purge" and an "audit". This gets rid of all defined but not inserted objects and recovers the dwg file acsii text code header and footer.

 

so now here are some advanced AutoCAD tricks that will help you deal with working with a large file:

 

_overkill

there is an Express Tool called "OverKill"

be VERY careful with it though = it is a destructive file management command. It deletes duplicate objects according to parameters you set. You will be suprised how many objects it finds. I have users whose files decrease 30%.

 

_partialopen

OK now you have as clean an acad file as possible. One way to work with it in pieces is to Partial Open the file. Most of us do not notice it but this is a very powerful tool. in your Open dialogue box there is a pull-down beside the file name field. Select "Partial Open" and then select only the layers you want to work on today. Viola.

 

Here are some suggestions for maximizing your use of xref.

 

_xref

Use the xref manager to Unload/Load only the part of the model you need to see. The CPU will only calculate what is loaded.

 

_xclip

learn to use "xclip" to only load a partial area of an xref. This can dramatically increase performance.

 

_refedit

you can work on an xref without actually opening it seperately using this command. It takes a little getting used to but can save a ton of time.

 

How about some system settings you can manage:

 

_viewres

fast zooms and large circle percents slow down graphics cards

 

_treestat & _treedepth

Each node consumes about 80 bytes of memory. The fewer objects per node of the oct-tree, the better the performance.

[Guest mwaychoff]

also for future reference don't get too caught up in the solids vs. surface modelling debate; because it all changes with ADT aecMass objects! They are the best of both and are now supported in Arch Studio, Arch Desktop, and Sudio VIZ.

[nisus]

Hi mwaychoff,

 

Can you tell us a bit more about those new aecMass objects?

 

tnx

 

nisus

[Guest Ph03Nix]

Hello people, let's see anyone can help me.... When i open the drawing in the Max/Viz, was made in the Autocad, a circle for example, looks like a polygon with 8 sides or less.... This always happens with circles, arcs, curves.... I try to use isolines command but don't work it..... Any ideas?

 

Thankz.

[STRAT]

yeah, it's the way autocad and max treat arcs - splits them up into 3 segments.

 

you either BREAK your arcs, therefore creating more verts in autocad first, or goto sub object segments mode and BREAK in there, or even up the shape steps in max to a high setting.

 

Personally, i never bring lofted/extruded arcs or circles in from autocad, i'll always RULESURF them first, gives me more control.

 

You could also try using splines, altho expect a shed load of verts then.

[cyborg]

@CHE

 

I have also been working with very huge files in AutoCAD, when you import your scene in MAX/VIZ you see the scene gets more "lighter"

 

The reason why your Autocad scene is so huge is because your "isolines" is high. Did you change it ? (default =4)

 

Under import (MAX) just use a 0.1 valute, and very thing will work out fine.. Hope it helps.

 

[ August 18, 2002, 12:53 PM: Message edited by: cyborg ]

[alastair]

I have a problem exporting geometry into Max.the file looks correct in autocad,but when I export the geometry gets messed up. I have tried all the welding and smoothing variables but nothing works.

blocks appear as surfaces and extruded objects gave a different depth /height when view in max.

I am using autocad 2000 and max 3.1The file is only about 2MB.

 

Please help!!

[Fernando Lino]

to clean up the file ...open it with recover or copy the objects and paste them in other file

-ADT has a tool to convert solids to masselements whiche use less memory than solid