Metasequoia BBS

[8078] Measuring perimeter and area of an object / Alsayed

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Hi Administrator and others who kindly can offer help here,

Is it possible to know more details on how Metasequoia Measure the perimeter and an area of a 3D object?

In the software index, what is explained is very short, like this:

When you click any point on the object, it measures the object's perimeter including the point.

XY
It measures the perimeter parallel to the XY plane. (as usual, I do the measurement in this axis).

In [Perimeter], it measures the area of cross-section on the object.

Most of my 3d objects (short cylinders) have ellipsoid shaped cross-section rather than a true circular cross-section. So wanted to confirm the way the Metseq. calculate both perimeter and cross-sectional area of this ellipse.

Faithfully,
Alsayed

2019-03-05 17:10

[8079] Re: Measuring perimeter and area of an object / 管理者

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You can check how to measure a perimeter and an area by a trial license. Please get it from the following URL;
http://www.metaseq.net/en/trial.html

The trial license offers all features same as Metasequoia 4 EX. The measurement is supported in Metasequoia 4 EX only.

2019-03-06 10:26

[8080] Re: Measuring perimeter and area of an object / Alsayed

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Hi Administrator,
I am already using Metasequoia for the measurements. The values of both perimeter and area given by metasequoia are faithfully correct. However, my question is how the software measures these two dimensions of a short cylinder with an ellipsoid cross-section shape (not true circular)?

Faithfully,
Alsayed

2019-03-06 10:45

[8081] Re: Measuring perimeter and area of an object / 管理者

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Ok, i see.

Metasequoia does not support a truly circular ellipsoid. It is just a polygon mesh looks like an ellipsoid. And, a perimeter is calculated by measuring a length of not a curve but a polyline on a polygon mesh.

For example, when you create a cylinder with a radius of 100mm, the true perimeter is 628.31853mm. However, a measured perimeter will be slightly shorter than the true value. Of course, a measured area will be also lesser than 31415.9mm^2. If you want a higher accuracy, you should increase the division of a circumferential direction of a cylinder.

2019-03-06 12:50

[8082] Re: Measuring perimeter and area of an object / Alsayed

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Hi Administrator,

Thanks so much for the informative reply. I understand your point.

How can I increase the division of a circumferential direction of a cylinder in Metasequoia?

Is it to change (mesh smoothing) from (Object) menu. I tried this (increase segment to 4) and the measurement has increased (but not significant) from 1.235 to 1.28 (perimeter) and 0.1054 to 0.1066 (area).

I can't do any further changes in my object in my 3d reconstruction software.

Faithfully,
Alsayed

2019-03-06 13:31

[8083] Re: Measuring perimeter and area of an object / 管理者

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You can select [Segment] and adjust the number in [Primitive] command if you want a new cylinder or other primitives.

[Mesh smoothing] can divide an existing mesh, but it does not ensure circularity. Faces around a corner edge will become fat.

2019-03-06 16:50

[8084] Re: Measuring perimeter and area of an object / Alsayed

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Thanks So much!
Sorry, in the second line do you mean Faces around a corner edge will become fat or flat?

Much appreciated!
Alsayed

2019-03-06 17:15

[8085] Re: Measuring perimeter and area of an object / 管理者

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When you apply the mesh smoothing to a simple thin cylinder, it will become like a fat barrel.

2019-03-06 17:57

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[8086] Re: Measuring perimeter and area of an object / Alsayed

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Thank you very much

2019-03-06 18:13