Hi all,
I am trying to import a surface model which is originally generated from Rhino without loss of parameters or constraints. Parameters mean, for example, length or thickness… and constraints mean surface or rectangle…
So when I export the surface model from Rhino, what kind of file type (.stp, .sat, 3mf…) includes all parameters AND constraints? I know IGES file does not have anything so forget iges file.
Regards
Jeong
As I understand it Rhino doesn’t have parameters or constraints. Just geometry.
What software are you trying to import the Rhino file into?
AIW is correct.
Rhino surfaces, curves, meshes, and annotation contain no additional “constraints” as you described.
Why did you ask the question the way you did?
What problem are you trying to solve?
Actually, the way he asks the question I understand “constraint” as object type.
and geometric parameter as objects definition.
So my answer is, IGES/STEP/OBJ whatever you export it to as long as it is not an image will most likely contain all of the above. 
Thank you for the comment.
Basically I was given a surface model originally generated from Rhino and I am trying to open into CATIA without loss of CAD data. In CATIA, I am trying to extract CAD data (CAD data means length, width or thickness of the surface model) from the imported Rhino model. I have tried with IGS file but, obviously, as IGES file does not have any CAD data only geometry, I cannot edit/redefine/recognise CAD data from the imported surface model. So what I was asking is what kind of file type from Rhino includes CAD data?
I probably I have not understood fully how Rhino design the surface.
Thank you for the comment.
Basically I was given a surface model originally generated from Rhino and I am trying to open into CATIA without loss of CAD data. In CATIA, I am trying to extract CAD data (CAD data means length, width or thickness of the surface model) from the imported Rhino model. I have tried with IGS file but, obviously, as IGES file does not have any CAD data only geometry, I cannot edit/redefine/recognise CAD data from the imported surface model. So what I was asking is what kind of file type from Rhino includes CAD data?
I probably I have not understood fully how Rhino design the surface.
Thank you for the description.
I am not a CATIA user.
What you’re describing as “CAD data” are easily obtained in Rhino with analysis commands like Length, Distance, etc.
In CATIA, are these values or parameters, settings you can change that will update the geometry?
That is exactly what I am trying to do with CATIA now.
I am looking for a file type - stp, 3ds or csv… (which are available from Rhino) which also can be edited/redefined in CATIA.
That won’t be possible, unless CATIA has some sort of “feature recognition” tool that can can be run after importing to add these constraints to the imnported geometry.
Rhino does not use parametric tools in the modeling process, so these do not exist for export.
Some parametric, feature-based modeling tools like SolidWorks, ProE, etc. do use these tools to create their geometry.
I have no idea if these parameters and constraints can be imported into CATIA or not.
I do not really understand
‘Rhino does not use parametric tools in the modeling process, so these do not exist for export.’
I just drew a simple rectangle in Rhino and when I type ‘length’ on the command window and click the rectangle it says 49.668 mm.
Can you explain more detail about what you said please?
In a parametric modeler, the process for creating your rectangle might be to sketch a rectangle, then apply length and width constraints to the rectangle to set it to a specific size.
Then later, you can change these values and the rectangle will update accordingly.
You “drive” the geometry with your parametric constraints.
In Rhino, when you create the rectangle, you can plop it in free-form, or you can type specific length and width values to create it.
However, there is no residual parameter attached to the rectangle to change later.
If you add dimensions to the rectangle, the values displayed are driven by the geometry. If you Scale, or “point edit” the corners of the rectangle, the dimension text will update, but you can not select the dimension text, and change it expecting the rectangle to change.
To expand a bit on John’s description:
In Rhino, if you would like to draw a rectangle you can, for example, pick “rectangle from two points” from a menu and then just place the mouse on the screen where you would like the first corner to be and left click, then move the mouse to where you want the diagonally opposite point and click. This will create a rectangle within Rhino whose size is determined by the particular screen scale you are using at that moment. The size will be in Rhino units. You can tell Rhino what those units represent (inches, mm, km) as a part of setting up a specific model. A different way of specifying the size is also available: you can type in the coordinates for each point to specify the exact location. Either way what Rhino creates is a rectangle - or more specifically, an object which is a set of four lines linked together. Rhino “knows” this object is a rectangle because you told it at the beginning with your menu selection that’s what it should be. Beyond that, there is nothing more for Rhino to export.
I’m not a Catia user either but I presume that this isn’t basically much different from how it’s done in Catia, although Catia probably has more methods available that allow for “parametric” construction and all the neat things that go with it. I suspect that if you can find the imported object in Catia you can add all the additional info you need to make it a Catia rectangle.
I understood what does ‘parametric modeler’ mean from what you said.
However, you also said
'In Rhino, when you create the rectangle, you can plop it in free-form, or you can type specific length and width values to create it.'
For me, typing specific length and width values to create it sounds like also parametric modelling because ‘user defines dimension’
I am really sorry I do not have a proper background of Rhino.
Nope. It’s more like drawing a line on a piece of paper. You draw it where and how long you want. You can do it freestyle or use a linear scale.
Either way, you just end up with a line with no enduring adjustment parameters.
Thank you for a comment.
Lets say if you design the rectangle in Rhino and export as a .3dm file which is a default file of Rhino. And you gave to me. If I open the .3dm file with notepad or whatever app which can show how .3dm looks like, does the .3dm file include dimention of the rectangle (x mm of width and y mm of length) and ‘object’ as well? or just full of point cloud?
The rectangle is what Rhino calls “A closed polycurve”.
It has four degree=1 (straight) NURBS curves with end points that touch and are tagged as being Joined.
You can use analysis commands to check the length each segment or the length of the entire polycurve.
Lets say I drew a lineand if I want to adjust it like 2.5mm, how should I do that in Rhino?
You could Trim it to length if it’s too long, Extend it to length if it’s too short, or Scale the whole thing by a calculated factor to get the length you desire.
You could also turn on it’s Control Points, and move one end to make it your desired new length.
Note: The capitalized words are Rhino command names.
Hi @jrlee8290
Just to add to the general discussion, it’s worth mentioning, that not many file formats carry the parametric data across. Most of the NURBS formats (if not all?) that have some sort of parametry are proprietary: You’ll have to own the program from which it originated to make use of the parametry. As mentioned, some programs have “feature recognition”, meaning that the software can analyze a given geometry and try to understand its composition (extrudes, holes, flanges etc.) and create its own parameters based on that, but that’s based solely on the receiving software’s ability the understand the geometry. Sometimes this works quite well for most geometric designs, but not for more organic shapes.
Regards, Jakob
In addition to John Brock’s suggestions you can also use BoxEdit to adjust the overall dimensions of an object in the X, Y and Z directions…