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# 3D volumes from node co-ordinates

## 3D volumes from node co-ordinates

(OP)
hi all,
Im trying to simply work out the surface area and volume of 3-D shapes. they are for transfer chutes between conveyors. Im struggling to make an algorithum that works, concavities are the main hassel.
cheers
duncan
Replies continue below

### RE: 3D volumes from node co-ordinates

How well defined are your surfaces? Do you just have a point cloud?

Are they basically flat sheets, with intersections?

Cheers

Greg Locock

### RE: 3D volumes from node co-ordinates

(OP)
Hi Greg,
Yes they are basically flat sheets of plate that intersect, each surface is usually defined with 3 or 4 points. aeach point is able to be located with x,y,z co-ordinates.
cheers
duncan

### RE: 3D volumes from node co-ordinates

There's a fairly crucial difference there. 3 points define a plane, 4 (generally) don't. If you can live with the 3 point ones then you can generate an equation for each plane(z=ax+by+c, I think), then calculate the line for each horizontal section, and so get a result that way.

On the other hand if you have curvature then things get far more difficult, one way is to use SurfGen.xls to define an easiy spaced grid of points at each Z value

Cheers

Greg Locock

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