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Author Topic: Working with Imported Geometry  (Read 4161 times)

Delaveris

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Working with Imported Geometry
« on: August 04, 2008, 09:46:35 am »

I've been trying to find the easiest way to work with importing Geometry from AutoCAD ABS (Autodesk Building System).  Since I'm dealing with large buildings involving many rooms, it would be best if pathfinder could extract the floor from the imported .DXF file, but this is not the case. (yet?)  So, I import the .DXF into Pyrosim, create a mesh that encloses the geometry that I wish to work with, save it and export it as a .FDS file, and then import that .FDS file into Pathfinder.  This works fairly well.  Any 3D objects have to be exploded before importing into Pyrosim, otherwise they'll just end up on the background image, and the finer the mesh, the better the resolution from the .FDS file. 

It would be nice if I didn't have to do all this for the time it takes, but also for the going through FDS to do it.  Any diagonal lines or rounded objects are converted into "sawtooth" geometry, which is the way FDS works, and is a necessity for that program; but at least Pathfinder can work with diagonals, if not with rounded edges. (yet?)  Also, imported geometry from a .DXF file straight into Pathfinder cannot be shown in the simulation results, whereas geometry from an .FDS file can be shown.

I understand that this is still the beta version, but I just wanted to see if these issues were going to be addressed.
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Charlie Thornton

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Re: Working with Imported Geometry
« Reply #1 on: August 07, 2008, 07:47:13 am »

I think they have a much better chance of being addressed now.  The only way we have to tell the difference between problems that matter and esoteric stuff is to hear about the real problems from users.

The import feature is definitely underdeveloped at the moment.  It was one of the first things we added to pathfinder so we could look at interesting test cases, but we never really went back and re-visited it.  Another missing element is a direct PyroSim (PSM) file import - that would at least give us diagonals.  I'd really like it to be able to crawl up stairs on a FDS file import (blocks only), but we have a limitation with representing single steps at the moment.  Occupants can't just walk over a section of floor that is 1 cm higher than another without the two being connected by a proper stairway.

In terms of a direct DXF import, the problem is a bit fiddly because we have to be able to properly interpret the lines and faces in the DXF as enclosing a space.  Usually there are a few layers that represent the key geometry and the other essentially add noise.  I think if we just put floor between all the enclosed spaces on a 2D model, you'd have fits getting rid of all the extra floor elements and merging the room parts that got busted up by the electrical system diagram.  I'm hoping that we can come up with some sort of workable wizard style solution.

On the bright side, the 2D editor does snap to DXF imported edges.  That can help make things a bit faster.

- Charlie
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Charlie Thornton

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Re: Working with Imported Geometry
« Reply #2 on: August 07, 2008, 07:56:12 am »

Also, if anyone has any DXF files that represent real buildings that they can share with us, that would help us out a lot.  I think we are still overusing our friend the moose for testing...

- Charlie
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