Hi,I’m a freshman ,but I am trying to get a Nurbs surface from arbitrary points which was collected by coordinate measuring machine .Therefore I’m here seek somebody help .
How much have you done with Rhino? Is your question about an assignment from a class? If so what is the subject of the class?
How many points are collected? Can you post a .3dm file or image of an example set of points? To post a file either drag it where you type a post, or click on the vertical arrow above where your type a post.
If there is a large number of point then the Patch command can be a useful tool for creating a NURBS surface. If there is a small number of points then other methods may be better than Patch.
You selected the openNURBS sub-forum. OpenNURBS is for transferring geometry between software. I have reassigned you post to the general Rhino sub-forum.
Of course you can’t just make NURBS from ‘arbitrary’ points. Trying to do so is one of the most tiresome tedious jobs you can do in all of CAD-dom and as such not really recommended unless you are a Rhino ninja.
I’m glad to recive your reply , I don’t know much about Rhino . I want to setup a software based on OpenNURBS lib. What I have said not very specific ,I’m so sorry for that . Here is picture ,is based on Qt to show these points ,the number about thirty thousand points.
I’m glad to recive your reply , it not be an ‘arbitrary’ points , It has a certain trajectory, just like my picture above. Oh I know this is a tedious job ,but this is my teacher command. 
OpenNURBS is not intended for nor sufficient for writing software which creates geometry. https://www.rhino3d.com/new-source/en/features/developer/opennurbs/
The openNURBS Initiative provides CAD, CAM, CAE, and computer graphics software developers the tools to accurately transfer 3D geometry between applications.
Note : openNURBS is an open source toolkit for only reading and writing 3DM files. Our full-featured development platform is provided in the Rhino SDKs.
A single NURBS surface is not practical for the geometry in the image.
Hi @dale ,
I’m glad recive your reply ,It doesn’t have to be NURBS surface fitting, it can be other surface fitting methods, because right now I just finished reading the book NURBS (Les Piegl), and he has a chapter introducing how to perform a NURBS surface fitting (approximation method) for a given data point.So that’s why I came here to find a way. If you have another suggestion ,please contact with me,I will appreciate you !
-Tao
Hi @davidcockey
Oh ! I may be finding another way to fullfill my purpose . For my purpose , do you have a better idea? like some good libs which could realize my ideal.Thanks !
-Tom
Is your assignment to write code, or to create the geometry?
How much experience do you have using NURBS? Have you created digital geometry?
Is there a reason not to use a combination of Rhino and Grasshopper?
In the first sentence of your first post you identified yourself as a “freshman”. In the United States that means you are a first year student at a university. Is that correct? Or did you mean something else, such as you are new to the Rhino forum?
Yes, I am a new one in Rhino forum.And I am a post-graduate in Asian,so there is an incorrect statements. Now I just read Les Piegl’s book about NURBS, and the task assigned by my professor is to write a program that can reconstruct NURBS surface,and I didn’t know what Grasshopper is . My opinon is finding a lib that can realize my assignment,and if I have to write the algorithm by myself I don’t think I can do that .