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nareshn2003

How to calculate area ?

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to compute the volume of an arbitrary closed mesh:

* make sure your surface mesh is triangulated (no higher polys)

* imagine a virtual tetrahedron using the three points of each triangle and the center of gravity (average of all points as an approximation)

* add in the area of that tetrahedron
(http://mathworld.wolfram.com/Tetrahedron.html, start at (24))
times the sign of [(center_of_tri - cg) dot (tri_normal)]

do this for the entire mesh.

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Quote:
Original post by nareshn2003
Hi
How to calculate area of three diamension convex or non-convex object area i mean dimension (Height,Width,Length) . I need entrie object dimension in max and min . So how can i calculate it ?

any suggestion ??

i suggest you to explain what you want more cleanly.

You want to
1:find surface area of your object?
or
2:find volume of your object?
or
3:find smallest axis-aligned box that your object is inside that box?
4:something else?

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HI

>>>>1:find surface area of your object?

== Yes I want to find surface area of object

or
>>>>2:find volume of your object?

No I don't want to find volume

or
3:find smallest axis-aligned box that your object is inside that box?
>>>No

Basically I want to find object dimension length, width and height in Min and Max. I mean Min Dimension and max Dimension in entire object.

If u have any confusion let me know




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It's actually damn confusing. You have to explain better.

Actually,

- "find smallest axis-aligned box that your object is inside that box"

and

- "find object dimension length, width and height in Min and Max. I mean Min Dimension and max Dimension in entire object."

seem to be the same.

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I think what he really wants is the minimum ORIENTED box enclosing any 3D shape. Right this time ? I suppose then the algo is well documented. Probably some eigen vector stuff involved.

Without precise vocabulary and concepts geometry becomes meaningless.

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yes, i think, minimum oriented box (i'd say , just "minimum box", or for websearch, "minimum bounding box")

keyphrase in google

some other pages:
1
some sources
look at:
"tight-fitting bonding-box that contains a given input point-set.the bounding box is arbitrarly oriented" i think it's yet another name for this....

(now everyone will come to gamedev for this info :)

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