Large Drawings

[Rich Rosemann]

Good Morning.

 

I've run into a brick wall with a very large Autocad model.  When runnung the Render command, the Preparing Model window opens up and never goes beyound opening the actually Render window.

I've tried rendering normal and in the Walkabout window.  Lots of trees.

 

Using the latest nXt w/ Autocad 2010, XP-64, Duel processor - 3.0 Mhz, 16 Gb Ram, nvidia card.

 

Am I running into an Acad limitation problem or a nXt limination problem, do you think?

 

I've tried rendering at 800x600 res. with no change.

 

Thanks

 

Rich Rosemann

 

[Roy Hirshkowitz]

There really shouldn't be any limitations in 64 bit-- at least none that you'll hit. If you're running out of swap space you'll get a large system-wide dialog box notifying you of this.

More likely some sort of bug. You can try sending me the thing-- I'll take a run at it.

http://www2.mcneel.com/upload/Upload.aspx
[e-mail] as the recipient

[Rich Rosemann]

Hi Roy

I'm getting no notification regarding swap file space. I have at times had XP notity me that it was enlarging the swap file size, but not in this case. I've let thr program run for 6 hours without any results.

The file is large (200 Mb. --It's not my fault). I need to render the entire area. I'm also restricted to proprietary property on this model and can't share at this time. I have been able to render with the terrain model unattached, but I require it to complete the render. Rendering it separatly and adding it in post editing is not a choice. My post editing is - limited. I havn't read of anyone rendering files this large here, so experience here may be limited.

I will built another file up to 200 Mb. and see if it fails. If I have problems, I will sent the file to you to play with. Thanks

Rich Rosemann


Rich Rosemann

[Roy Hirshkowitz]

If you can't reproduce it-- see if you can get permission from the clients for me to have a look at it. I won't publish or keep it. These types of bugs can be hard to reproduce. I doubt if it's strictly a size thing.

[Wayne Williamson]

Rich

I do many large files and my experience has been spotty with files over 100mb. I have posted issues with one recently but have had several other that worked fine. I only have had 2 over 200mb one was a good experience and one not. I can not point to any one thing as an issue but if you are running a 64 bit system you should never have a memory problem.

When I have had problems I have done an audit of the file and copied everything into a brand new file. This sometimes works, don't ask me why - I have no explanation but sometimes things will suddenly work better.

Also I have found that x-refs save time & memory for autocad but in the end are not reliable for NXT modeling with large files, many times they render like materials are not attached to objects or wall components. No one can explain this to me but in all case inserting the same items as a block & exploding has fixed the problem.

I don't know if this will be helpful but I hope so. Goodluck.

[Rich Rosemann]

Hi Wayne & Roy

The trick of copying to a new drawing is almost as old as Autocad. I havn't tried this yet. I may tonight. This was almost a sure fire way to clean out nasty information. The fact that you had on and off success suggest to me that the file is at fault. I will see. I'll build another file and see what I get, Roy. If it behaves the same way, I'll send. Thanks

Rich Rosemann

[Rich Rosemann]

Hello, Roy,

With regard to the memory limitations I asked about, I did some testing of different file sizes with the drawing I had problems rendering. THe first test was the complete drawing at 265 Mb. I brought up Task Manager and watched as my physical memory, starting at 11 Gb, dwindeled down to 1Mb and died there. By removing the fence surrounding the plant, which lowered the file size to 220 Mb, I was able to render without any problems. I assume there are just too many faces on the fence for 11 Gb of memory to handle. I guess, in a way, there are size limitations in rendering a drawing, but the limitation is memory, not Autocad or nXt. Someone once told me the no one needed more then 6 or 8 Gb of memory with a 64 bit machine. I beg to differ.

Rich Rosemann

[Roy Hirshkowitz]

No Rich-- you're likely running into some kind of bug here-- not a memory limitation. Provided your swap file can handle it you should be fine. Like I said, if your swap file can't handle it, you get a system-wide dialog box informing you of this and giving you some choices. This is very different than the limitation which occurs w/ 32 bits. The amount of RAM on your system is only related to performance, at this point.

Whether the problem is nXt or AutoCAD I can only guess. Until I get this reproduced here under the scope we won't really know the nature of the problem.

Incidentally, file size, and memory footprint are only distant cousins. It's very easy to produce a small file that will allocate 15GB. Conversely, large files don't necessarily equate to large memory allocations for nXt.

[Rich Rosemann]

Hi again, Roy

That information is very interesting. From what I think you stated before, once the nXt engine is run, it runs seperatly from (any) Autocad influence, as far is memory usage is concerned. Is this correct?
If I remember correctly you had stated, at some time past, that nXt is influenced by the processor speed and number of cores and not the video card or the amount of Ram available. That is not all corrent, I'm sure, but in watching the physical memory dropping in the Task Manager, I could only think - memory leak. Your last statement does have me confused, though:

"Incidentally, file size, and memory footprint are only distant cousins. It's very easy to produce a small file that will allocate 15GB. Conversely, large files don't necessarily equate to large memory allocations for nXt."

Are you talking about number of polygons per drawing, as a small, compact drawing
w/ thousands of polygons versus a drawing extending hundreds of feet, but few large polygons? Are am I missing the point completely? I love being confused.

Rich Rosemann

[Roy Hirshkowitz]

A memory leak symptom is a rising allocation-- not a falling one-- so no-- what you're seeing is not a memory leak. Memory "leakage" means memory which is allocated but never released. For example, if you pressed the render button several times and saw the allocation go up significantly each time without recovering-- that might be a memory leak.

Yes-- during the rendering process AutoCAD is mostly dormant. It does, occasionally spring to life for actions like it's own autosave-- which causes nXt to take action as well. nXt communicates with AutoCAD quite a bit when it's receiving the geometry to render-- then not much after that.

I can create a simple sphere dwg that would produce millions of polygons just by turning the tesselation up-- that drawing would be quite small. I can also produce a huge 2D drawing which wouldn't generate any polygons at all to render. All kinds of non-graphical elements can add to the size of a dwg file.

[Rich Rosemann]

Understanding comes in bytes.

Rich Rosemann

[Roy Hirshkowitz]

Yep. BTW when you notice the allocation drop precipitously (like you did) what you may be witnessing is the program attempting to shut itself down-- but getting stuck somewhere in the middle because something has gotten messed up.

[Rich Rosemann]

When you say "The Program", are you referring to nXt, or to Autocad? In either case, is there a solution to the dilemma other then reducing the file size, or rather the number of polygons? Would farming out to another computer of any help? Questions, questions.

Rich Rosemann