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Topics related to the Grasshopper-ARCHICAD Connection and the various tasks that can be achieved with it.

Moderators: Karl Ottenstein, LaszloNagy, ejrolon, Barry Kelly, gkmethy

Hi Laszlo,
As you might be aware, IFC is not quite the "One Stop Shop"
it should have been by now, and that results in various
interpretations and conversion "noise" between relatively
conventional BIM platforms.
As Grasshopper is to ArchiCAD what Mick Jagger is to Sinatra,
I am currently focusing on very boring stuff, like just getting
curved or double slanted walls to convert properly, in a sense,
training a high flying acrobat to walk a straight line on solid ground.
The main issue at hand is to end up with as many "useful" elements
on the ArchiCAD side of things, so the workflow can be as continuous
as possible from GH to AC.
There are many strange issues, and if Graphisoft could lend a hand
then maybe an imported Curved "ifcWall" will convert to an Archicad
curved wall and not just a curved polygonal wall, which is useless for

The really cool stuff is yet to come, I am sure of that :-)
Gil - your work is great.

With the whole OPEN_BIM marketing push on at the moment it is abundantly clear that GS understand their survival depends on the success of IFCs.
I agree it should be a 'one stop shop' - and if it fails then GS may as well close up shop. Everyone will go where IFCs are irrelevant...because one software will rule them all...

Frankly - I hope GS are all over someone like you, who is pushing IFCs to the limit, so that the promise of IFCs are delivered!
rwallis -
A L L credit should be given to Jon Mirtschin,
a brilliant engineer & programmer from down
under and the person actually doing all the code
crunching, founder of Geometry Gym.
We are aware of the "openBIM" thingy,
but GS are nowhere to be seen (yet)
in this specific effort.
This isn't about credit, but I would like to publicly thank Gil for donating his personal time to helping propel this forward on the Archicad front.

OpenBIM is about collaboration, there is no "one sided handshake" in this venture.

Grasshopper/Rhino is at it's strongest in the concept/competition phases of projects, and at some stage in design/development moves into a more settled phase of documentation/exploration etc in software such as Archicad. The other aspect of Grasshopper is it's propagation with massive acceleration at educational institutions, so watch and wait a little for it to really emerge (as well as the economies to support new project development).

I'm glad for the work Gil has done in demonstrating this work (and building confidence in the process with Archicad. I agree, there are impressive examples that will soon emerge from this establishing work.
NURBS based roof to Archicad 15

Hi All!
While work on the Grasshopper-IFC-Archicad issue is ongoing,
There is an alternative method for bringing into AC NURBS based
roof structures.
My concern is with achieving NATIVE AC elements to work with,
rather than resorting to GDL.
Here are a few images, and I will outline the method in the end.

Attached Image:
This curved roof was created in Rhino/Grasshopper using 3 distinct
NURBS splines: one for each "long edge" and one as the "top" spine.
Currently, such irregular forms can't be created with AC shells.
Roof Check 3.jpg

Before I outline the method, I must say that the current state of
the Archicad platform is frustrating, due to the fact that it hardly
supports any consistent & useful workflow regarding such "Freeform
Modeling" matters - and after 12 years I have my eye on switching
platforms as I am really tired of waiting on GS to get it nailed.

Rhino is NURBS and Archicad is Mesh.

In Rhino
1. Model NURBS surface - in plan form!
2. Use Grasshopper to MESH the surface -
you have very good controls for doing this!
3. Use Grasshopper to insert POINTS at MESH vertices
4. BAKE the points

EXPORT selected POINTS as comma separated TXT file

In Archicad

1. Generate a Mesh using Surveyors-Data-File
The mesh could look messy but continue...
2. Use the Mesh-to-Roof plug-in to convert each mesh face
to a roof element.
3. Set roof elements display to "Show on ALL stories
4. Delete the mesh
5. Delete erroneous roof planes

This method is an interim workflow and is nowhere close to how
things SHOULD be - but it works.
Enjoy -
Good old mesh tool... Abused for almost anything.

My take on this: the tools in ArchiCAD seem to be meant for their meaning (wall, roof, slab, terrain), but are in fact mostly geometric (extruded horizontal, extruded vertical, sloped/projected contour etc...).

Look at the shell tool: it is not a roof or wall or slab, but it is mostly a geometric shape. And for some architecture, this seems to be really required.

So once we get more faithful geometry into our ArchiCAD model, then we have to think again about the information behind it... E.g. using slabs for flat roofs and using meshes to generate roofs which are in fact panels opens the door for problematic interpretation further down the line.

As a long-time ArchiCAD user, I am also becoming quite frustrated over all limitations that don't seem to be resolved anymore.

Please continue the investigations. I'm attempting a different road at the moment, but this is far from working, so I hope to present something usable later on...
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