Techniques to read dwg-format…

[Anonymous]

I’m going to accomplish this: I have ADT-dwg drawings with any types of objects in. I’d like to traverse the dwg and retrieving the following information:

1. The geometrical data for the objects. Best would be if I could get some kind of array of 3D points or similar.
2. Read the associated property sets from the objects.

What I’m (at fist) wonder in which way I can tackle this problem. I’ve earlier used the AutoCad ActiveX interface and read Property sets from there but the geometrical data do I haven’t found using that technique :-(.

All tips are welcomed!

[Anonymous]

You can get to some geometry with ActiveX and .net, but you will have to get the OMF api in order to get at everything.

Unfortunately, the OMF is only available to ADN members.
So you will have to join if you want access to it.

This question will get better response in the ObjectARX group or the .NET groups under Autocad.

[Anonymous]

Ok thanks. I've already have thoughts about to be an ADN member.

So you say there is only one way to get ALL the geometrical data for AutoCad Objects, and that via OMF?

[Anonymous]

You can get geometrical data from AutoCAD objects with ObjectArx. For ADT, you will need the OMF.

OMF can get curves from 2d objects and faces/vertices from 3d objects. All the objects properties are exposed in OMF as well; door width, frame depth, etc, whatever is there.

The 3d objects can also be queried for components, so you can get at the sheetrock and studwall components in a wall object (as an example).

Just realize there are two types of 3d solids in Autocad. There is the true, accurate solids of the acis modeler (AcDbBody objects). Then there is the faceted modeler for ADT (AModeler), all ADT walls,doors,windows use this 3d api.

One caveat, the OMF is NOT documented nearly as well as ARX, it takes a fair amount of trial and error programming to figure out how to do things.

[Anonymous]

Ok, maybe I should dig into ARX a little bit more. Do you have any short tip on where to start searching the API?
It would be great if the samples in the ObjectARX installation could be of help. I've searched among the samples and will continue to do that. Any tip of a good one?

[Anonymous]

I would start with samples/database/ents_dg and samples/database/plinIter.

If all you are interested in is AutoCAD entities, you may be able to get to them with .net as well. I know that the dotnet api for Acad has been expanded greatly in 2006. I don't know if it is complete enough, I haven't had a chance to check it out.

Unfortunately, I have to provide my add-on product for ADT2004,2005, and 2006, so the 2006 net API is still unusable for me.

[Anonymous]

What about using the GbXml or IFC Utilities that are out there?
You can grab a serious amount of data and read it into a database.
I'm no programmer but, it's a direction.
-
Sean D. Burke
Autodesk Architectural Desktop Certified Expert
Author, ADT 2005 CBT
~Coming soon~ ADT 2006 Blended Learning & Support
http://www.4dtechnologies.net

[Anonymous]

I'll scan through your suggestions. Thanks!