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DB071-Visitor
1-Visitor
Aug 27, 2014 1:39 PM UTC
Solved

How to create a 3D plot of a solid defined by coordinates

Hello,

I'm trying to 3D plot a solid defined by the X,Z coordinates and a constant for the width (Y). I am using the surface type to create a filled surface for each side of the shape. I am able to create most of the surfaces, but cannot figure out how to "fill in" the front and back faces.

I have been searching the forums and have found examples of this, but none have shown a surface with more than four points, which I believe may be an limiting factor. I have tried numerous methods of how to arrange the matrix, but my understanding of the matrix structure required for the surface plot is limited.

Please see attached worksheet.

Thanks!

Werner_E
Werner_EAnswer
25-Diamond I
Aug 28, 2014 10:33 PM UTC

If you don't mind a few extra lines her is another solution.

Facettes in Mathcad's 3D plots are quadrilaterals which may degenerate to triangles or even line segments. So you will have extra lines in every case. One approach is to make the sides an extra plot like Richard did and don't show the lines for this plot.

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6 replies

RichardJ19-Tanzanite
19-Tanzanite
Aug 27, 2014 6:52 PM UTC

Like so

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DB071-VisitorAuthor
1-Visitor
Aug 28, 2014 2:40 PM UTC

Thanks for the response. That works for this situation, unfortunately when I change the coordinates it that doesn't work. I need an method that will work for any combination of coordinates. eg if I change the last z coordinate to 252.55, then the surface no longer lines up.

Can a surface not be defined by more than four points? That would make it much easier.

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Werner_E
Werner_E25-Diamond IAnswer
25-Diamond I
Aug 28, 2014 10:33 PM UTC

If you don't mind a few extra lines her is another solution.

Facettes in Mathcad's 3D plots are quadrilaterals which may degenerate to triangles or even line segments. So you will have extra lines in every case. One approach is to make the sides an extra plot like Richard did and don't show the lines for this plot.

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DB071-VisitorAuthor
1-Visitor
Aug 29, 2014 2:29 PM UTC

That's perfect! Thanks very much. Is there anywhere I can read up more on how to generate these facettes? Google wasn't helpful.

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Werner_E
Werner_E25-Diamond I
25-Diamond I
Aug 29, 2014 3:33 PM UTC

Is there anywhere I can read up more on how to generate these facettes?

Nothing that I would be aware of. After all creating that kind of "solids" is awkward and cumbersome anyway and in no way satisfying. After all Mathcad isn't made for this as its not a CAD program.

I guess it would be the best to create a plot consisting of two objects like Richard did as you can suppress the unwanted lines that way beacuse you can edit the surfaces separately.

My solution is just a quick hack and in no way perfect. Just change the third z-coordinate from 257.15 to 255.15 to see what i mean.

I created a mesh for the sides by just connecting every point to a single point which I know is part of the surface - the first in the list. So all facettes are triangles (or line segments).

1.png

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