The biggest DWG file I’ve ever seen

The biggest DWG file I’ve ever seen

Today, I tried to investigate a DWG file that one of my users couldn’t open. It wouldn’t open for me on an old 1 GB PC. Trying a PC with 4 GB didn’t help, and neither did experimenting with various releases of AutoCAD. Depending on the release, AutoCAD would either try to open the drawing and eventually die with an out of memory error, or would instantly inform me that the drawing was too big to open. I don’t have access to a 64-bit version of AutoCAD (which might possibly be able to open this monster on a PC with more than 4 GB of RAM), so the drawing is effectively useless.

The drawing is 242 MB (254,145,119 bytes), which I’m pretty sure is the largest drawing I’ve ever encountered. Based on a plot of a previous revision of the the drawing, it should be about 200 to 300 KB, i.e. one thousandth of the size it is. Looking at other oversized drawings from the same company shows that they are large because they contain lots of invisible proxy objects from a third party add-on or vertical variant of AutoCAD. Wblock will dramatically shrink such drawings, but care needs to be taken to ensure it’s not stripping out anything that might possibly be needed.

What is the biggest drawing you have ever come across? Did you discover what was making it so huge?


  1. Chris Cowgill

    About 5 years ago, I reduced a drawing that was 304 mb down to about 3 1/2 mb mostly by removing duplicate objects. It was a map, that had about 3 or 4 copies of the linework on top of itself. I dont quite know how long it took to clean it up, but I do know I used the express tool Overkill to remove the duplicate linework.

  2. daveea

    over the years i’ve seen some gimongous DWG files… here are the top 5 causes for them that’ve run into and each cause had to be handled very differently:

    1. a lot of content: working out in the mines where people are digging holes the size of entire cities, a mile down, and over a 10 year period, survey data gets pretty huge. these cases were handled by busting up the flat data into bite size pieces according to its use and a lot of training on polyline vertex optimization.

    2. duplicate objects: crappy or careless or oblivious CAD work, these cases were handled with custom duplicate entity removal routines and a lot of training on duplicate entity prevention and detection.

    3. cheap raster-to-vector polylines from hell: horrible or incorrect settings and conversion routines which created contours using polylines with billions of unnecessary vertices. these cases were solved with custom polyline weeding routines and training on raster-to-vector software configuration.

    4. 3rd-party/other CAD proxy objects: it’s amazing how much junk a 3rd party app or an alternative CAD program can add to a simple drawing. these cases were handled by source investigation, hacking, and by uding AUDIT, WBLOCK, DXF search/replace and other elegant junk data stripping tools when the plots were verified as the only data really necessary for keeping.

    5. exploded entities: these weren’t duplicates, they were just mishandled native entities — hatch patterns probably being the world culprit. thank god most of these cases were organized by layer and deletable/re-doablk.

  3. the_mini_guy

    I am still green in C3D 2010, i went through the Beta testing & am only running a 32-Bit PC.
    I ran a 360Mb survey (14000ha x 1km vertical) & compressed it down to 100Mb surface file (after deleting the drawing objects) then data shortcut it to a new file = 1Mb. now i can freely model away..

  4. Earl Kubaskie

    “Nodisplay” styles in Civil 3D are your friends!

    If you’ve ever seen mapping of arctic coastal areas, you know that a few square miles may contain a thousand small lakes/ponds. Back at the turn of the millenium, imports from Microstation that contained those polygons with a “fill” gave you a dwg with a few thousand flat 3D meshes, needing *many* times the memory of a closed polyline. Worse yet, his was just prior to the lightweight polyline feature’s debut.

  5. Dave Tee

    Not Autocad, but Visio…. about 15yrs ago so not so fast machines.

    One of our project managers drew up a cabinet full of computer gear – switches, routers, patch panels, etc, looked so good he drew up all 68 cabinets in the equipment room, then cut and pasted them into a master drawing. Failed to notice that each drawing was already 1.5MB. Note it was cut and paste, not copy, so about two weeks work that he wasn’t able to open with his laptop.

    We eventually opened it on one of our cad machines – took 45 mins to open the file.

  6. Susan Lafleur

    Not a DWG file, but a co-worker found some AC$ (temp files) yesterday that were 1 & 2 GIG!!! The associated drawings weren’t even close to that. No wonder his computer was bogged down!

  7. Daniel

    Regularly Autodesk software have problem with memory. They are often slow. I didn’t compare precisely autocad with Bentley microstation but my sense tell me Microstation is better in handling drawings.
    I think it takes all needed resources at the first and after the file is opened, it is easy to handle.

  8. I work with 700+ MB Revit exports as XREFs in my drawings all the time. It takes a few minutes to open and the drawing is super sluggish while the XREF is loaded. The problems I have found have to do with what is being processed by your GPU versus the CPU. CAD can only use one GPU at a time to process, so even in your multi-core/multi-graphics card computers you’re still only using one processor.

    Would be pretty sweet if Autodesk could find away around this, files aren’t getting any smaller or less complex.

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