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Jan 18, 2006
04:08 AM

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Jan 18, 2006
04:08 AM

CLASS OF SURFACES

Hi,

Many a times i have heard guys talking about Class of surfaces

but when i approached them they could only tell me very little

about it (i.e G1,G2 ).

Kindly see if you can help me to get a beter understanding

about it, in detail.

Thanks in advance

Pradip

Many a times i have heard guys talking about Class of surfaces

but when i approached them they could only tell me very little

about it (i.e G1,G2 ).

Kindly see if you can help me to get a beter understanding

about it, in detail.

Thanks in advance

Pradip

3 REPLIES 3

Jan 18, 2006
10:42 AM

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Jan 18, 2006
10:42 AM

Isn't Wikipedia a wonderful thing?

http://en.wikipedia.org/wiki/Freeform_surface_modelling

To quote:

The continuity is defined using the terms

* G0 - position (touching)

* G1 - tangent (angle)

* G2 - curvature (radius)

* G3 - acceleration (rate of change of curvature)

Caleb Coburn

Mechanical Engineer

Roche Diagnostics

http://en.wikipedia.org/wiki/Freeform_surface_modelling

To quote:

The continuity is defined using the terms

* G0 - position (touching)

* G1 - tangent (angle)

* G2 - curvature (radius)

* G3 - acceleration (rate of change of curvature)

Caleb Coburn

Mechanical Engineer

Roche Diagnostics

Jan 18, 2006
12:00 PM

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Jan 18, 2006
12:00 PM

Just to add to what has been said before, the surface connections are sometimes defined in terms of G (G1, G2 .. ) or C (C1, C2 ..)

With G only the directions of the vectos need to match, ie for G1, the tangent vectors between the two surface patches will point in the same direction. For C1, both the direction and value of the vectors need to be the same.

For the naked eye, it is difficult to make out the difference between the G and C continuities.

If you are from around Detroit, you will also hear about Class A or Class B surfacing. Class A , used on Outer Body panels, is Curvature countinious and Class B is just Tangent countinious. I still havent figured out whether it refers to G or C countinuity !!!!.

Bottom line is, in shaded mode, if you cant figure out where one surface ends and the other one starts, that is Curvature countinuity, if you see a sheen line (think of a radiused edge) it is tangent.

Hope that helps

Suresh Pillai

First Technology Safety Systems

With G only the directions of the vectos need to match, ie for G1, the tangent vectors between the two surface patches will point in the same direction. For C1, both the direction and value of the vectors need to be the same.

For the naked eye, it is difficult to make out the difference between the G and C continuities.

If you are from around Detroit, you will also hear about Class A or Class B surfacing. Class A , used on Outer Body panels, is Curvature countinious and Class B is just Tangent countinious. I still havent figured out whether it refers to G or C countinuity !!!!.

Bottom line is, in shaded mode, if you cant figure out where one surface ends and the other one starts, that is Curvature countinuity, if you see a sheen line (think of a radiused edge) it is tangent.

Hope that helps

Suresh Pillai

First Technology Safety Systems

Jan 18, 2006
01:43 PM

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Jan 18, 2006
01:43 PM

http://www.cs.berkeley.edu/~sequin/SPLINES/SplineLect1.html

http://www.cs.berkeley.edu/%7Esequin/CS184/IMGS/Continuity.JPG

http://www.cs.berkeley.edu/%7Esequin/CS184/IMGS/Continuity.JPG