fitting 3d solid to point cloud

[Roben]

Hey everyone, it's my first post on this forum. First of all i would explain what i am trying to achieve. I have to write a program that match an 3d solid to a cloud point which represent this object. As far as i know there is no function in AutoCAD that return the shortest distance betwen an 3d solid and point, this would help me alot (i guess so).

I think i could use bounding box, make one for the object and one for points (points change to smalest shapes and use union to create one object) - this will let me make bounding box. Next i have to compare the dimensions of this boxes and fit/match them.

What do you think about this solution?, any opinions and other ideas will be appreciated.

Ps: I know this idea is't pretty as my english.
Ps2: I'm learning Visual Lisp for a half year so excuse me if i don't understand something.

[Hippe013]

Welcome to Cadtutor!

I too have been trying to create objects from point cloud data through the use of lisp. I would suggest reading up on best fit algorithms first. There are formulas for best fit Lines, Planes, Cylinders and etc. I am currently working on extracting a 3D Orthoganal Best Fit Plane from a set of data points. Meaning that I am trying to minimize the distance from a point perpendicular to a plane. This is a work in progress. As for your solution, I don't believe a bounding box would be the route to go as a bounding box is simply the extents of the object and not its shape. I would suggest, as I stated, to read up on the Best Fit Algorithms to get started but this is just my opinion.

regards and happy coding!

Hippe013