Rhino for general modeling?

Discussion in 'Software' started by M&M Ovenden, Dec 3, 2006.

  1. M&M Ovenden
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    M&M Ovenden Senior Member

    I have been using Cadkey for quite a few years so I am fairly fast and agile with it. Now it seems to me that my 1998 version is starting to become obsolete and I am considering upgrading to a new cad package. Rhino sounds excellent for the price and everybody seems to really like it. I have explored Rhino with the complete trial version but haven’t gotten in as complex of solid modeling as I currently do with Cadkey. I feel I will have a hard time doing a fair comparison before I can handle new software as well as the current one but that takes time. So I need opinions.
    I know that Rhino is far superior then my version of Cadkey when it comes to surfaces but I want to know how well it handles detailed solid models. Will I get frustrated if I switch or happily surprised? How intuitive is the modeling? Will I have good control over the shapes generated? Is file exchange smooth? What about 2d drawings and dxf export, any trouble?
    I know there are many threads on Rhino but comments are mostly orientated towards the hull design, is it as good for the detailing and general modeling?

    Thanks,
    Murielle
     
  2. JPG Designs
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    JPG Designs Pieces and Parts

    Rhino don't do solids....
    Yes, they group surfaces together and call it a "solid" but its not compaired to Cadkey.
    I use Rhino to create expanded shell plate, then export DXF to Autocad for part definition and nesting. Also, I offset the 3D surf as a "solid" for thickness and export ACIS file of "solid" to Autocad to be limked to the expanded parts.

    File exchange is smooth, if you have all the parameters set properly.

    I don't use Rhino for 2D "drafting", Autocad is much better suited than Rhino IMHO.

    I work on vessels from 8' to over 500' for plating and frame/long'l traces. Has served me well and my customers have been pleased.

    JPG
     
  3. marshmat
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    marshmat Senior Member

    Well, Murielle, that depends on what your detailed modelling is.
    Rhino works with NURBS surfaces for everything; a solid in Rhino is just a closed polysurface. Not the same thing as a solid in Cadkey or SolidEdge which is actually modelled as a solid object.
    You can be as vague or as precise in the detailing as you want to be; so long as you follow good modelling practice (keep everything as simple as it can be), the files stay reasonably small and manageable.
    Compatibility is very good, I have yet to come across a format in my work that it can't read.
    It is a very intuitive program, certainly much more so than most parametric modellers. It will take a while to learn how to make the most of it though.
    If you're thinking of buying, I would make sure to get v.4, so wait just a hair longer. http://www.deskeng.com/index.php?option=content&task=view&id=1360 gives a decent summary of some of what it can do.
    It is not enough on its own to completely design and build a complicated boat. If you have a lot of 2D drawing involved as well, you will need something else such as AutoCAD that's meant for 2D. And if you want to design, analyze and directly CNC machine your cleats and railing fittings, you might find a parametric modeller better. But for overall design and bringing an idea to life, Rhino is hard to beat.
     
  4. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    You can buya 3.0 now and pay a little extra to get 4.0 when it is released in a few weeks (I guess).

    I also make surfaces only in Rhino, then I make sections wherever I want a frame (transverse or longitudinal or any direction) and then export to dxf/dwg to make solids in AutoCAD or BricsCad.
     
  5. M&M Ovenden
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    M&M Ovenden Senior Member

    For what application does it make a difference having closed polysurface in opposition to solids. My guess is that the main difference is for file exchange with software which recognizes solids. Is it an issue for CAM softwares? If Rhino considers volume between surfaces, then for the operator those polysurface entities can be considered as solids? Rhino still does boolean operations and seems to operate as if it was using solids. I don't quite understand the difference between “solid” and “closed polysurface” as for me a solid is a closed polysurface entity of a different density than it's surrounding.
     
  6. marshmat
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    marshmat Senior Member

    The difference is to do with the mathematical definition of an object.

    A surface in Rhino is, mathematically, exactly that; although it exists in 3-space (x,y,z), the surface itself has only two dimensions (u,v). It is created by evaluating a mathematical relationship between the 'control points' of the surface; this relationship depends on the (u,v) co-ordinates for each individual surface. Several NURBS entities can be joined to model the surface of a 3-dimensional object; this is how Rhino does solids. But a Rhino solid is still a collection of 2-dimensional surfaces, and although closed polysurfaces can be treated as volumes, mathematically they are still combinations of 2D surfaces.

    A solid in SE, SW, Inventor, etc. is more readily described as a collection of primitive 3D shapes, such as boxes and spheres, which are added and subtracted by Boolean operations. The resulting part is a three-dimensional entity in 3-space. In some fancier packages, NURBS surfaces themselves can form part of this definition. But the program continues to see the complex shape as a combination of elementary 3D features.

    For CNC machining, the CAM program usually cares only about the surface of the part. It does not care what mathematical method was used to define that part, as long as it can extract an outer surface from it to cut. Most CAM programs work equally well with both NURBS and solids. Others, such as some rapid-prototype machines, just treat everything as a mesh anyway.

    Where 'solid' modellers have an advantage is in mechanical design etc, where the relationships between different features are most important (ie. Hole2 offest from Hole1 by x=12,y=33,z=0). Changes in one part are propagated through the relationship tree as the definition of the part is redrawn. NURBS offers much more flexibility of form and shape, but as objects are defined independently and not in terms of each other, it can be a difficult technique to use when revisions are constantly being made, as successive parts then need to be redrawn instead of updating themselves. Rhino4 is reportedly working on improving this weakness.
     
  7. Steve Baer
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    Steve Baer Rhino Developer

    I wrote a large set of the new drafting tools for Rhino4 and was just wondering what you consider is missing for getting your 2d drawings put together. I'm interesting in finding out what you feel you need so I can add this in a future release.

    Thanks,
    -Steve
     
  8. M&M Ovenden
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    M&M Ovenden Senior Member

    Thanks Matt,

    You cleared a few things up for me.
    So if I get all this strait, solid modelers tend to have better parametric features then CAD based on NURBS. So it is possible to make as complex of models with Rhino then with a good "solid" base CAD packages but updating and modifying models can be a more tedious task.
     
  9. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    Steve, I had a look at a beta version of Rhino 4.0 a few months ago.
    Now I am downloading the latest version, rh40beta_en_20061115.exe.
    While I wait (14% now :) I use this opportunity:

    I suppose Layouts with several Viewports with different scale and vpoint and layer settings is implemented?
    What about associative dimensions?
    Can you dimension on a layout?
    Do the dim object remember what you snapped to?
    Can "Make 2D drawing" and sections be dynamically updated?
    Do you have (title) bocks with attributes?
    Fields linked to file properties?
    Fields showing object properties (area for example)
    Object Snap Tracking?
    26% now, I'll be back :)
     
  10. Mudz
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    Mudz Junior Member

    It would be nice if Rhino had some kind of interface with a 2d drafting package that automatically updates the drawing as the model changes (as per soildworks) Rhino is perfect for modelly and obtaining geometry. I export the geometry from rhino to Autocad to do all the working drawings.
     
  11. marshmat
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    marshmat Senior Member

    Some of these comments may be redundant as I have yet to get my hands on Rhino4. Version 3.0 sr5 is, for the moment, still the hub of our team's CAD arsenal.
    As far as 2D goes, the one thing I really love about SolidEdge is that it constantly updates all the 2D drawings affiliated with a part whenever that part is modified. It would be good to have something similar in Rhino: When I take 2D data from Rhino, then change the model, it would be nice to be able to update the 2D without starting that drawing from scratch.
    The same goes for 3D features that are created from other parts, it would be nice to be able to link (for example) a deck with the gunwale it was created from, so that when you change the hull shape, the deck stays attached to it. (I have heard rumours that 4.0 might be able to do something like this?)
    My only other beef with Rhino probably has little or nothing to do with Rhino. Exporting a model to STEP format, then bringing that into a CFD preprocessor such as Gambit, often results in a lot of duplicated edges that have to be manually connected in the meshing engine. I have yet to determine whether this is the fault of Rhino's STEP export or Gambit's import.
     
  12. Tim B
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    Tim B Senior Member

    I see 3D CAD as the system to develop the design. It would be nice to be able to see a linesplan, but it is only really necessary for checking the fairness of a hull. The days of deriving water-plane area from a lines-plan are long gone, I'm glad to say. That said, I'm writing my own software for hull design on Linux, so I'll probably implement that feature in my own code.

    What I would like to see is a port of Rhino for Linux, and I know I'm not the only one. So far, the only response that I have got from McNeel and co. is that there is no intention to port Rhino to Linux, and when pushed for a reason I've been told that it's too complicated, or there isn't the market demand. Both these reasons seem a little unfounded to me. If anyone can influence the current Rhino development plan, then perhaps that would be a good way to go.

    Tim B.

    PS. Please DON'T tell me that Linux is a server operating system. The desktop capability of Linux is actually better than Windows XP. KDE 4, due for release sometime in 2007 should knock the socks off Vista.
     
  13. marshmat
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    marshmat Senior Member

    I too would love to see this. If not a full port, at least the elimination of the call to 0.0.0.0 in the licence manager, that has been reported to screw it up when running under emulation.
    Even KDE 3.5 can pound Vista into the ground on 90% of desktop machines. I've heard from a lot of people that the Aero environment is a huge resource pig and that most current machines show a strong preference for the simpler environments.
    Most of the software I need is either already available for Linux, or has equivalents that are. Rhino is one of the very few exceptions.
     
  14. Tim B
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    Tim B Senior Member

    I meant in the prettyness of the interface. We all know that technically KDE is far superior technically and resource-wise.

    Tim B.
     

  15. marshmat
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    marshmat Senior Member

    I meant visually, too.... sure, Aero looks good, but since almost nothing can run it properly, what's the point? K is simple, pretty and effective.
    I would really like to be able to switch to Linux. Too much CAD tied up on Windows though, at least for now.
     
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