guess this one for the developers but i thought id post it here as there may be some people who have some experience.

i work as an architectural cad specialist focusing on tools and modelingmethods for complex geometry. always on the lookout for new tools i have come across houdini a cople of times.
like allways; some bright people in the cad world are really happy that they have invented a precedural cadsystem. sure, the beta is great. but what about houdini i say, its been around for years…

some questions:
1. what length float precision is used in the geometryengine of houdini?
2. is there much geometric ‘cheating’ going on to optimize performance?
3. how does houdini cope with very large scenes, measured in small units, in ‘world’ b-box terms?

goodwill,
thomas w

As far as I know from importing CAD models into Houdini the the predcision level is single floating point, I believe CAD is double floating point.

Not sure what you mean by geometric cheating.

But as to large scenes it's the best non CAD package I'd say. Because you can deal with all objects straight off disk, just references stored in the file.
So for instance we have files with 3000+ objects and the file is only 10-15 Mb in size.


Hope this helps a little.

thanks simon,

my intesion is to go the othew way round: from houdini to cad and my hopes is that i will be able to trust the geometry to be accurate. if singlepresicion float is used throughout then it may become a problem for very large scenes.
by cheating i mean that geometric curve or surface continuity is adjusted in the rendermesh rather than in the actual nurbs. eg. how does the software handle piecewise geometry and joinde surfaces?

the efficient instance handling is good news! what kind of transformatins can you do instances?

/thomas

From what I have seen all of the operators in Houdini that create approximations (e.g. fillet) have an error tolerance setting. You can trade off more error/less vertices against less error/more vertices.

Double-precision is very rare in the 3D animation world. I don't know of any renderers that use double-precision, so there isn't much point in modeling with double precision. (of course if you want to output to a CAD system, that's another matter)

I would check out Rhino as well. They boast about extremely precise NURBS operations, and I think Rhino uses double-precision as well. I'd use it more except I don't really like their GUI.

rhino is what i use most of the time. the precision is good, the sdk is well documented and the scripting is also very powerful. unfortunatly rhino has zero parametric ability. there is no built in solver of any kind.
im not looking for a modeling tool to do traditional mcad work but rather a tool to investigate complex relationships between many parameters and constraints.

/thomas

I am using Houdini for Architectural Visualisation. I can say that it's great for that side of the field, using procedural routines for stuff like windows etc is great. I have a library of fitting for each of my clients, when a new job comes in, I can quickly set up a model. The compositor makes it easy to create scenes with d-o-f, layering with photos of the real-world skies and foliage etc…

yes you can undo a screw with a knife but I'd stick to using acad or catia or whatever you use for CAD as they are the proper tools for the job, otherwise you will be making things harder trying to convert Houdini to a job it's not meant for.

thankyou mookid!

i can see the benefits of wich you speak, the procedural nature of the software must be a great timesaver in modeling for visualization. especially knowing what limited and often very incomplete material goes out tho the viz studios from the architects sometimes.

my angle on using houdini is not to try to replace catia. that would be plain foolish. nor is it to do the things that other cad systems do better. the aim is to do the opposit, all the things that are near impossible to do in traditional cad without having to develop proprietary code (takes time, needs interface to be used by designers, etc.)

non standard architecture i guess…

by now im curious enough about the software to spend some hours learning it. thanks everyone!