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Unit Normal Vectors using a Field Point


Unit Normal Vectors using a Field Point

I have a colleague who is trying to extract the unit normal vector at a (large) number of discrete points on a surface.
Picture a basketball with a datum point at each intersection between seams (assuming basketballs still have seams, but you see what I mean). Then imagine a pin stuck in the ball, one at each datum point, sticking out normal to the surface of the ball. We want to know the X,Y,Z coordinates of each pin-head.
Pro/E will give us the unit normal vector at a point if we use Analysis/Geometry/Point, but only one point at a time.
I cannot help thinking, however, that we should be able to use something like a field point and a User-Defined Analysis to give us the values for all the points in one file.
Our problem is that, whilst we can get the Unit Normal Vector for any of our points, or we can get the full set of values of, say, cross-sectional area across the whole surface using a field point and an analysis feature. We cannot, however, work out a way to use the geometry analysis as the basis for the analysis feature.

Do you have any suggestions? Is there a nifty work-around? Am I barking up the wrong tree with field points & UDA?

I look forward to your constructive suggestions.


John Wayman, C.Eng, FIED
Senior Mechanical Engineer

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Many years ago I needed to list the locations of mirrors and the path length of the laser running through them. This was way before analysis features existed. I had a pro-program that prompted for some mirror locations in xyz and others in polar coordinate. To position the points in the model I use polar to xyz translation equations, and in the relations I also set parameters equal to the values. I had additional relations that calculated the path length and set parameters to that also.

In an assembly drawing of these laser beam paths, I created a repeat region that reported all the values I was interested in.

Sample relations
Conversion from Spherical to Cartesian coordinates

Conversion from Cartesian to Spherical coordinates

Conversion of Rho to Cylindrical radius

David Haigh
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