topic Re: Importing solid geometry (BREPs) in Collaboration with other software

Importing solid geometry (BREPs)

Anonymous — Thu, 22 Aug 2013 23:14:16 GMT

hello,
is there a way to import solid geometry (BREP) into Archicad? Something saved as *.SAT or similar.
IFC2x3 - although handling BREPs internally - comes into Archicad as tesselated mesh. Anyway to import it as solid (maybe as Morph object, which btw is based on solids or meshes?)

thanks for input!

Re: Importing solid geometry (BREPs)

Piotr Dobrowolski — Fri, 23 Aug 2013 19:55:44 GMT

Triangulation is a problem of most 3d formats unfortunately...all depends on the imported object itself, but in most cases afer import You can change the object to morphs - even if the triangles will be there too, but can be removed manually.

Best Regards,
Piotr

Re: Importing solid geometry (BREPs)

Anonymous — Fri, 23 Aug 2013 20:02:02 GMT

So, no way to import SAT file straight into morph(are you saying this is the equivalent of solid geometry in other packages?)

for a case like this solid geometry is a must:

Uploaded with ImageShack.us

form is generated in rhino, watertight solid geometry. please advise me in getting it flawless into archicad.[/img]

Re: Importing solid geometry (BREPs)

Piotr Dobrowolski — Sat, 24 Aug 2013 11:59:04 GMT

The best connection is via Cinema4D, You can also try 3ds format import - Rhino probably export to this format - if the UV-map is good there will not be unneeded triangles (fingers crossed).

If You loaded this via IFC - and there are triangles - You can change the resulting object to morph and than modify further - hiding edges etc.

If the object is complicated You may change all edges to hidden - the visible edges will still be visible in planar views like sections.

Best Regards,
Piotr

Re: Importing solid geometry (BREPs)

Anonymous — Sat, 24 Aug 2013 12:48:13 GMT

No, as i said mesh importers are not acceptable. I loose geometry data and that renders sections and plans unusable. Morph after selecting "hidden edges" is all funky.

Can someone confirm that in archicad 17 there is no way to import solid BREP geometry?

Cheers,
Chris

Re: Importing solid geometry (BREPs)

Anonymous — Sat, 24 Aug 2013 13:33:36 GMT

have a look at this:
http://geometrygym.blogspot.com/2012/08/gh-to-archicad-openbim-ifc.html

so... archicad has the capability to import BREPs from IFC2x3 file, only its not documented well. maybe someone from dev team would like to shine some light on how to prepare IFC files so they transmit solid geometry?

much appreciated!

Re: Importing solid geometry (BREPs)

Piotr Dobrowolski — Sun, 25 Aug 2013 07:13:17 GMT

If You need parametric geometry from GH...I think it is not possible out of the box. If someone wrote a plugin that would convert GH script to gdl than maybe possible but not in the whole spectrum of possibilities.
IFC does not translate the script by any kind - the only parameters would be materials/finishes and size (IMHO).

Translation by IFC will produce AC objects native or GDL (if the more complicated)
If You wish to have morph of them: You need to change the resulting objects to morps (right click menu on selected object) - as for any AC object.

Best Regards,
Piotr

Re: Importing solid geometry (BREPs)

Anonymous — Sun, 25 Aug 2013 08:01:19 GMT

the output from GH is a baked SOLID. it has nothing to do with how the object was created- at the end its BREP geometry.

Please understand i don't want double conversion (Solid >> Archicad makes mesh of it >> Convert to Morph (what is morph? solid or mesh? i don't know, maybe doesn't matter because it changes the geometry drastically)

Again, the question is simple: Is there a way to import solids as native solid/surf archicad object (no meshing)?

Regards,
Chris

Re: Importing solid geometry (BREPs)

Piotr Dobrowolski — Sun, 25 Aug 2013 11:40:20 GMT

Maybe I do not fully understand Your need but all 3d entities in any 3d software are displayed/rendered etc as meshes even if they are parametric.

Morph is a mesh type object...and all AC objects GDL and native are meshes (under the hood - when talking about 3d)

Morph can be a linear object, surface or solid depends on the faces, if you make a cube and delete one face - You will receive object that is not solid, but can be solidified.

Best Regards,
Piotr

Re: Importing solid geometry (BREPs)

Anonymous — Sun, 25 Aug 2013 12:56:34 GMT

yes, i am aware of that every geo object (nurbs, brep) is at the end represented by a mesh tesselated version of itself. but thats just display, the underlaying geometric info prevails and is accessible when needed.

the purpose of this topic was to find out if anybody (preferably one of the developers of archicad) knows a way to import such geometry in archicad WITHOUT tessellation (triangulating for approximation).

the previously attached picture is of a form generated in Rhino and saved as *SAT file, which after importing into Revit can be treated to sectioning, filling and further documenting. tesselated mesh that after import to Archicad just wont cut it.

i mentioned IFC import, which might be it, but somebody has to shine some light at how to prepare it (rhino side).

thanks for your input,
chris

Re: Importing solid geometry (BREPs)

Piotr Dobrowolski — Sun, 25 Aug 2013 13:16:13 GMT

You need someone to write a "big" plugin that would translate one scripting language (GH or so) to another (GDL) - it is not impossible, but it is a big task. I do not think the complete translation will be possible anyway. It might be a kind of GH script interpreter (addon) working inside AC that would create a GH script object on demand - but in the end creating a GDL object binded to this addon (low level GDL or binary) - so the modification would be possible via GH script.

For most users the import of dummy objects is good enough so I do not think such a "translator" would appear in the near future.

Best Regards,
Piotr

Re: Importing solid geometry (BREPs)

Anonymous — Sun, 25 Aug 2013 13:23:19 GMT

Its not about grasshopper or rhino. Its about archicad not interpreting solid geometry.

Re: Importing solid geometry (BREPs)

Anonymous — Sun, 25 Aug 2013 18:45:30 GMT

I can't really advise on importing SAT or geometry (I don't know enough about archicad).

If possible, you can define the IFC file using constructive solid geometry. Graphisoft have implemented many of these. So if you can define your base shape as an extrusion and then cut voids/openings out of it, you might be able to achieve something as you desire. Note my gh plugin converts the nurbs to a polycurve of arcs (to rhino document tolerance).

GH Definition http://geometrygym.wikidot.com/local--files/ifc/130825%20extruded%20wall%20with%20opening.gh

Sample http://geometrygym.wikidot.com/local--files/ifc/130825%20extruded%20wall%20with%20opening.ifc

Rhino itself doesn't store the explicit history on a brep (polysurface) with the sequence of modelling steps to create it. It only stores the resulting nurbs faces and trims. IFC4 has advanced breps (similar to SAT or DWG) with nurbs faces, but I don't know if Graphisoft intend to implement this when they release their IFC4 importer.

I hope it helps a little,

Jon