Hello,
I would like to extract all the walls from complex .DWG files that comes from the conversion from a .PDF by AutoDWG software. In these big multi-floor plans, there are multiple types of walls (exterior, office, corridors, etc) that have their own thickness and interior composition (trusts, insulation, etc.) and it's not even always clear to the eye where one type of wall ends and another starts. To give you an idea of the problem, here are two examples of very small regions of these kind of plans.
Note that I'm NOT interested in starting from a high resolution image of a scanned floor plan as the information is already vectorial in the DWG file. Also, I must do it by programming and as little user intervention as possible as this must be part of a bigger software solution.
I would be glad if anybody could propose software, libraries or papers describing methods to extract wall information from such a .DWG file. I guess OpenDWG seems to be part of the solution but if someone has more first hand experience with this problem, I would like to know about that!
https://www.opendesign.com/
I was using Allplan software for this kind of tasks. You may find brief information thru the presentation that I have prepared which is given in the below link;
https://issuu.com/fgamimarlik/docs/allplan_tender
Hello Evren Serpel ,I can't seem to be able to access the site. Could you just attach a pdf ot ppt file to your post?
Thanks!
Thanks Evren Serpel ! Do you know if the wall extraction could be scripted or programmed with an API from Allplan? My problem is to develop something as automatic as possible to work as input to another software so all the GUI operations shown in your presentation would have to somehow be automated (at least the ones for wall extraction).
Bruno Martin, to my knowledge the only way of doing this using layers while drafting the drawing. I don't know any software that could distinguish these kind of information from the PDF file.
Your target is an IFC formatted file, correct? You would need to create and target the "axis " entity, check for the collinear axes that create closed polygons, and then present those to a user as room volumes. The algorithm could guess whether the line pairs are (say) balcony railings, walls, or columns, but inherently the intelligence required to distinguish those would need to be a true learning-based AI, which sounds like a step beyond what you are trying to do.
OTOH, if the API stops at that point, takes a guess, and askes the user to confirm, it could continue based on the wall axes. It can *create* standard IFC classes, but I not see any way that that it couId recognize all of them from old non-uniform .dwg files.
You can only get information from a Computer Aided Design drawing that you put into it. (the old computer saying: stuff in = stuff out). Put the dumb reference file in the background and you have to model in the walls with the parameters you need to get out. I gave up using 2-d drafting may years ago in lieu of smarter frames.
That is not necessary true in the future (stuff out = only stuff in), because it is possible to find two close parallel LINE or PLINE entities in a .dwg file and then create an axis between them. The algorithm can see if two axes are close to intersecting and treat that as a corner, in order to trim the lines. But beyond that we need to establish some recognizable conventions so that the user can understand what the AI processor is doing participate in generating 3-D architectural entities correctly and interactively.
True, but even if we use automatic the "snap" and "trim" capabilities of a CAD system, you still have to add intelligence , dimension and orientation through interpretation of the original *.pdf file to be able to extract totals from the model entities.
Adding dimension and orientation to a wall can be done the way (say) a raster file is converted to a vector file -- it is just a set of computations within straightness and intersection tolerances. Since the original lines are straight and we have trimmed the corners, this should not be a "wicked" insoluble problem. But in Revit all these walls have to belong to a hierarchy ("intelligence" means "this wall borders room xxx and is xx'-xx" high and made of 'nnn'") , and that is too big a mess to assign them algorithmically.
Actually intelligence is two different things now that I think about it -- for Bruno's purposes he does not have to add "wall type 'nnn'" right away, so metadata is not critical. But the polygon (room-id) that the wall surrounds, and perhaps the wall height, are needed for the Revit wall instance database, and those are hard to establish.
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