3d blocks

[foxbyrd31]

Is it wise to build blocks to use in 3d models?

I am working on an apartment building. In 2d I created a block of a typical unit and copied and rotated it around as needed. Can I use the same principle in 3d? Can I attach materials inside the block editor? (I built the whole thing as a sketch model with no materials, and now want to make it pretty!)

Any tips, tricks or suggestions are welcome!

 

I'm working in ACAD2010

[SuperCAD]

It would be better to create a file for the 3D model only and then XREF it into whatever drawing you're working in. If you make a block, each time you make a copy of that block you're duplicating the 3D solids which will increase the size of your drawing (and possibly corrupt the file if it gets too large). By using XREFs you'll keep the file size low.

[nestly]

The problem I've encountered with 3D blocks is the Flatshot doesn't project them.

[foxbyrd31]

SuperCAD, I'm not sure we are talking about the same thing.

What I wanted to do was create a 3d "typical unit" and make a block of it. That way I can just copy the whole unit instead of having to subtract out each opening, in each floor, then inserting each window, each balcony etc. I was thinking that building a 3d block would save me time and keep me from accidentally missing a mullion or something, and if the client decides half way through that they want different size/shape windows I could just switch it out in the block and have it update on the whole building. Does that make sense? is there some other logical way to do this that I am missing? Were you thinking for me to make an X-ref of the typical unit and copying it?

 

nestly, I had never heard of Flatshot. It does sound useful though, so the inability to see the blocks could be a downfall if I try and like this command.

 

I was noticing too that the outside of my building had lines showing where the "typical unit" blocks met. Is there a way to do away with those so the outside looks smooth? Or do I just have to bite the bullet and make an entire floor and copy it then union it into an entire building?

[SuperCAD]

Trust me. Making a "block" and duplicating that block will only cause you problems. AutoCAD will literally keep adding each solid body in that block each time you copy and paste it. The file size will become enormous and possibly cause a corruption of the file. I've been down this road before so I know exactly what you're after.

 

Research XREFs. That will be much more advantageous to you since AutoCAD will only duplicate the reference to the original model, rather than the actual model. It will keep your file sizes way down. If you zoom in to an XREF it will only look like it's made up of a bunch of surfaces rather than solid bodies, but you can still flatshot it and use your section planes as if the solids were in the drawing.

[nestly]

This topic interests me because I currently use a combination of 3D blocks and 3D Xrefs in my 3D projects.

 

Trust me. Making a "block" and duplicating that block will only cause you problems. AutoCAD will literally keep adding each solid body in that block each time you copy and paste it. The file size will become enormous and possibly cause a corruption of the file. I've been down this road before so I know exactly what you're after.

 

Are you certain that's correct? All the documentation I've ever read says that block definitions are stored in a block table and AutoCAD references that table when drawing a block. Perhaps 3D blocks are handled differently than 2D blocks, but I was under the impression that having multiple instances of a block (3D or otherwise) should not significantly increase the size of the drawing.

 

The problem I have with making every 3D part it's own Xref is that the layer list becomes very large and difficult to manage.

[Oppie]

The problem I've encountered with 3D blocks is the Flatshot doesn't project them.

 

I never encountered this problem. The only thing to keep in mind when using FLATSHOT or SECTION PLANE is that you only use SOLIDS

 

Still, use the XREF method.

[nestly]

I never encountered this problem. The only thing to keep in mind when using FLATSHOT or SECTION PLANE is that you only use SOLIDS

 

I should have said "Flatshot doesn't always project them' I'll post one later if I remember, It's just a just a bar joist bridge made up of angles and Wide flange beams

 

Still, use the XREF method.

 

So if you were drawing a house in 3D you'd make a separate 3D drawing for every different size window, door, roof truss, light fixture, etc and xref them all? Components like doors and windows aren't typically xreffed into 2D drawings, they're inserted as blocks, so why wouldn't that also be true for 3D drawings? Basically, that means you'll have a different layer for every door size. I can see making the garage or out-building there own drawings, but not relatively simple repetitive sub-assemblies

[SuperCAD]

So if you were drawing a house in 3D

 

Yes, in large 3D models everything should be XREF'd into the drawing. To start with, drawing a house in 3D in plain old vanilla AutoCAD is a tad bit foolish. Since AutoCAD (prior to 2012) doesn't have any way to "link" the 3D model to the drawing views that are projected from it, and changes need to be done manually and increase the possibility for error.

 

I'll share a personal experience with you on this very subject. I had to draw a retail storefront that was made up of:

 

1. Steel tube framing
   
2. Wood cladding
   
3. Over 100 different sized window frames
   
4. Different colors and thicknesses of glass in the various windows
   
5. Wall sheathing
   
6. Wall finish tile
   
7. Ceiling framing and finish
   

 

With just modeling the solid bodies alone, the file became too large and AutoCAD would crash when I tried to do anything. I had to break up the entire storefront into multiple files (i.e. one for the steel, one for the cladding, 14 sections of windows) and XREF them all together in order for it to work. To further complicate the project, since the windows overlapped each other they had to be installed in a specific order, so I had to have different levels of window that I could turn on and off to show the GC how to install them.

 

Again, trust me. XREF's are the way to go for large 3D models.

[Denimoth]

Trust me. Making a "block" and duplicating that block will only cause you problems. AutoCAD will literally keep adding each solid body in that block each time you copy and paste it. The file size will become enormous and possibly cause a corruption of the file. I've been down this road before so I know exactly what you're after.

 

Interesting. I always make blocks of all my solid parts because it keeps the file size smaller. A block works like a Xref, except that the xref drawing (the block) is saved within the same drawing file. All a block does is tell autocad where to insert the block "part" and it's orientation. Same as a 2D block.

 

Try this example. Make a solid part of something. Cut and paste it a dozen times and save the file. Now repeat the process but using a block of the original part. Compare file sizes. The drawing file where you use multiple instances of a block is significantly smaller.

 

Xref is a good way to go as well, especially when working with very complex 3D models that make file sizes extremely large. Keep in mind the separate drawing files should be well organized should you need to send someone else the cad file later on.

[SuperCAD]

I just tested it.

 

Solids Only = 17.7 MB

Blocks Only = 17.2 MB

XREF's Only = 131 KB

 

The greatest benefit of using XREF's over blocks is making changes. When you put a block into another drawing, it has no reference back to the original geometry. It becomes it's own entity. If you change the original file the block will not update (unless, of course, the original block is in the file that you are working on). With XREF's, when you make a change to the external file, it will reload itself when the drawing that has the XREF's is opened, ensuring that you have the most current copy of the file.

[Denimoth]

I just tested it myself with a quickly made solid.

 

Arrayed the solid so that I have 144 copies of it in one file = 339 Kb size.

Used the same part, turned into a block, and made 144 copies of it in one file = 74 Kb in size.

 

or

 

Saved the single solid part to be used in a seperate drawing as a Xref = 68 Kb.

Inserted single part as a Xref in seperate drawing, made 144 copies. = 65 Kb.

Total size of project files = 68 + 65 Kb = 133 Kb

 

Maybe we're not talking about the same thing? I've attached my results for kicks and giggles. (doh, my non-block solid array was too large. Just open up the file "solid-temp.dwg" and array it 12x12 with spacing of 150 units and save.)

 

Xref would definitely make the primary drawing file smaller in size, but don't forget to take into account the file sizes of your reference parts. Granted your xref'd file is 131 KB, but add to that number the size of the source drawing file (which I'm guessing should be around 16-17 MB).

 

Also worth noting is that your computer is still opening up the other xref'd parts into memory, using up as much resources as a file with internal blocks. Inventor users are familiar with this as it displays the number of opened files in memory. Autcad doesn't show this, not directly anyway.

solids.zip

[SuperCAD]

We're comparing apples to buildings here. Your files aren't even 1MB. AutoCAD can handle things that small. With my file you're looking at 131K with XREF's vs 17.2MB with blocks.

 

I've got 12G of RAM on my computer, so that isn't the problem. The fact that AutoCAD cannot intelligently handle a very large file without problems is the limitation (and one of the many reasons why we're ditching ACAD and going with SolidWorks).

[foxbyrd31]

I had no idea I was going to open such a can of worms! I see the advantages of each, and my computer is new and has lots of memory, so I will have to try it both ways and see which works better for me. It is very unlikely that I will have to share the drawings with anyone else in electronic format, so that eliminates those issues.

 

Thank you all for you help! I love this site, so many helpful people! (and I'm sure you will be hearing more from me as I re-learn 3d and rendering!)

[SuperCAD]

It's not really a can of worms. Just two people vetting their methods. The problem is the comparison between the two examples. One used very small file sizes and didn't find much benefit to do it one way over the other. The other used very large files, similar to what you would find in home construction, and found a lot of value using the other way over the one. Your method will depend on the size of the files that you are copying.

[nestly]

Yeah, I don't view the discussion/debate as a can of worms either. I see it as a chance to learn.

 

So far, I tend to agree with Denimoth. His ideas agree with the conventional thinking concerning 2D blocks, however as of yet, I haven't seen any evidence that the same principles do not apply to 3D blocks.

 

Yes, individual drawings will be smaller, but I think Denimoth is probably right that AutoCAD is going to consume roughly the same amount of system resources displaying x-number of 3D objects, whether they're all in one file as solids, stored only once in the drawing, but replicated many times, or stored externally in xrefs and replicated many times.

 

I'm going to have to try this out for myself to figure out which is more efficient, although even if the Xref method turns out to be more efficient in terms of system resources, I just don't think I'll be able to get on board with xreffing hundreds of relatively small parts/assemblies such as doors or windows into a master drawing.

[SuperCAD]

17.2MB vs 131K wasn't enough evidence? I thought that was pretty clear.

[nestly]

The file size alone does not tell the whole story. Does every extra instance of the Xref require an additional 131KB to be displayed. My guess is that it does, if not more, at least on the video memory size, and probably in the system memory as well.

[Denimoth]

Nestly is correct. What a drawing does when it displays one or more xref drawings, is essentially building an index file, that tells Autocad where the xref'd drawings are located in the computer, and where to insert those drawings and it's orientation.

 

Try this example. Create your drawing and save it as Building.dwg. Now, create other drawings that you will want to insert into "Building.dwg" as an xref. Lets say you created 5 files this way, call em suite01.dwg, suite02.dwg, suite03.dwg, suite04.dwg and suite05.dwg. Lets say you insert these files (as an xref of course) into your Building.dwg and copy them several times over as you make the floor layout, and then repeat the process for additional floors. When your done, save and close the file, Building.dwg will be a small file size because it's only storing the file path location (like a link on a web page), the insertion points, the layer it's inserted as, and it's orientation relative to the UCS. Note that the file is small, just like what Supercad is saying. Now, delete the five other drawings (suite01.dwg, etc). Your Building.dwg stays the same size. But if you open it, all you will see is a text describing the path of the xref files. Autocad can't find those files because you deleted them and therefore it doesn't know what to draw or what should be seen. It can't load that information from the other files into it's memory. If you save Building.dwg again without changing anything, it will stay the same size, even though it's not showing anything but the file paths to all the xref files you used.

 

Since AutoCAD needs the other drawings to build your assembled 3D model, you therefore have to take into account the file sizes of every other *.dwg you used as a xref.

 

The huge benefit of using Xrefs is that you are not putting all your eggs in the same basket. What I mean by this is that if your primary file (Building.dwg in my example) gets corrupted or accidentily deleted for whatever reason, you will not loose everything as you will still have all the other files you used to build your Xref model. You just need to put them back together again instead of starting from scratch. Unlike if you use nothing but blocks all in one file, and it gets deleted, corrupted, whatever, well... you're pretty much screwed.

[SuperCAD]

Edited for content

Edited June 16, 2011 by SuperCAD
I was very tired and realized that what I posted was rude.