Nurbs surface is reconstructed based on arbitrary scatter

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. :worried:

OpenNURBS is not intended for nor sufficient for writing software which creates geometry.

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 @Tao_Chen,

Why do you need a NURBS surface? Would a mesh suffice?

– Dale

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 !

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 !

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 .