CompuServe Thread

#DXF information

9 messages in this thread
#122299From: merlin farmerSep 6, 1994 9:12 AM
I did not know for sure where to direct this question to, therefore I have simply thrown it up here for all. Simple question, I think. I am in need of DXF information. Actually, I need to know everything about DXF, I have an architectural walk-thru project comming up very soon, (my first), and the architectural firm is a few hundred miles from here. I am somewhat unclear as to the best method of saving (exporting) DXF files with AUTOCAD as well as (importing) DXF to 3D-STUDIO. I do not have any problems with the test DXF files that I have exported from ACAD 10 to 3DS but I am unfamiliar with ACAD 12. I know there is more than one method of saving the file. My question here is what is the best method to accomplish this. I am sure that is dependant upon how the design is structured (see, I am not an architect or I would have used a different word there) (g) I am wanting to avoid kicking the DXF back an forth over a 200 mile area. I do not have ACAD 12 or I would simply figure it out for myself. Any information would be greatly appreciated. Any sources available would be appreciated as well. Thanks in advance Merlin G. Farmer Crystal Cave Animagix VOICE (618) 985-8154 CTS
#122441From: Bob ProkoppSep 6, 1994 10:22 PM
Hi Merlin, You should have no problem bringing a .DXF from AutoCAD12. The DXFOUT of R12 and R10 are pretty much the same. R12 will have more data of course, but 3DS is primarily interested in either 2D lines on a single plane or 3D faces. If the AutoCAD model is made up of 3D Face geometry, you're that much more ahead of the game. You can import the file and start applying materials to the walls and floors. If you're given only 2D floor plans, you can still use them by impporting them into the 2D Shaper, making sure all the vertices are joined, and then use the 3D Lofter to extrude to elevation of the walls. R12 still has the ability to create filmroll files. This was a filetype used by AutoShade that only looked for 3D surfaces. If your client is going to give you a .DXF, also ask them to include a .FLM. The FILMROLL command will allow them to make this file. Ask if your client has AutoVision. If so, AutoVision can do .3DS conversion while you're in R12. One note of warning. Find out if the drafters use some sort of layering conventions for thier drawings. 3DS has a 64,000 face per object limit. 3DS asks you how you wish to import a file, Layer, Object, or Color. I've found Layer to be the most controlable, but if the drafter has put everything on a single layer, the 64k limit could be exceeded and the .DXF won't import. You're then forced to use Color which can run you into the same problem if they've drawn everything in one or two colors. If you have to import at an Object level, you can end up with many small parts that you to piece together. I hope this helps, Bob
#122461From: Phillip L. MillerSep 6, 1994 11:25 PM
A word of caution – AutoVision does NOT convert DWG information to 3DS the same way that 3DS interprets the _same_ model in DXF format. – Phil
#122607From: Bob ProkoppSep 7, 1994 2:34 PM
Hi Phil, That's true. Once the model is in 3DS, there will probably be some further massaging needed. When I've done this, the first thing I do is make a selection set of the entire model, then Surface/Normals/Object Unify. Even this process has become outdated for me since Gary Yost shipped his latest IPAS libraries. I use his OPTIMIZE routine religiously, now. Bob
#122460From: Phillip L. MillerSep 6, 1994 11:14 PM
You might want to check out Chapter 11 of "inside 3D Studio" for a fairly detailed account of DXF to 3DS. – Phil
#122766From: merlin farmerSep 8, 1994 8:03 AM
Phil, thanks, I have been meaning to buy that book anyway. Merlin
#122495From: Dietmar RudolphSep 7, 1994 2:56 AM
Merlin, you don't need to know much about DXF for bringing models into 3DS. It's more the problem to _construct_ the model correctly (i.e. putting 3DS objects on different layers) than the transformation process itself. In any case, if you really want to know 'everything' about DXF, check into this: – The AutoCAD software manuals (DXF chapter of the customization guide): This text is very compressed and requires a detailed knowledge of AutoCAD internals. The complete chapter is available for download as DXFDOC.EXE from the libraries of the ACAD forum. – The book "DXF standard" (which I co-wrote): This is a >500 page hardcover book containing not only the complete specification of each and every DXF structure (while not requiring AutoCAD knowledge), but also hints and rules for working with DXF files. The text (approved and authorised by the DXF creator Autodesk, Inc.) is written for both end users and converter programmers and uses a textual, tabular, graphical, and formal description on all DXF entities. The book comes with a disk full of DXF tools (viewer, manipulator, ASCII-binary converter, release converters, complete test suite a.s.o.) While most of the book is multilingual, the basic text is written in german language. Ordering information as well as an english language
#122764From: merlin farmerSep 8, 1994 8:03 AM
Dietmar, Thank you for the reply. I will DL the DXFDOC file. The book sounds very interesting and may be looking into that soon too. I do not however, read german (g). Thanks again Merlin G. Farmer Crystal Cave Animagix
#122785From: Forcade & AssociatesSep 8, 1994 9:46 AM
Merlin, As Dietmar has said, your real problem will be dealing with how the Acad modeler has built the model. Layer organization is one aspect you will need to work out. The default for 3DS is to convert an entire layer into a single object. Good if you planned it this way, bad if you didn't. If the Acad modeler is using 3Dfaces to model surfaces chances are that many/most/some will have their normals facing the wrong way. You can try using 3DS to automatically fix the normals. If the model was done correctly on all other respects this will probably work. If not, then it could get worse. The other modeler may not be snapping endpoints to each other, just going by what looks cloe on the screen. When you bring this into 3DS and weld the vertices, they may not weld. I have even had clients give me a wireframe that was exactly that. They had used 3Dlines to trace out the edges of the building. No surfaces, just lines. I had to go into Acad and trace over the lines with faces. A real time waster! I suggest you have them send you a sample file ASAP so you can see what they are doing and make plans to correct or deal with such problems. Good luck. Terry Gilbert Forcade & Associates