Happy July 4 With Captain America

SHIELD2

Avengers continues.  Captain America’s shield for July 4th.  Seems like a simple modeling task, but actually there is quite a bit of geometry and mathematics involved.  I tried to model it by 2 ways:  adaptive component and traditional family and found out adaptive component is not necessarily a better way to model than traditional family.  Let’s find it out.

The Geometry

It is simply a series of revolve to create the star, the star background, the red and white bands.

GEOMETRY

The Mathematics

There are quite a number of mathematical relationships between the parameters: the radius of shield, the radii of inside and outside curvature, the radius of the star, the width of the band.

MATH1

MATH2

Method 1: Adaptive Component

It seems to me adaptive component would make it easier to construct the star by using points placed on circle by Normalized Curve Parameter.  So I started with adaptive component.

The Star Background

The blue Star Background is a revolve with a void extrusion of the star.  The revolve is created with the lines of the inside and outside curvature.

STARBACKGD1

STARBACKGD3

The points of the star are placed and located by Normalized Curve Parameter, 0.0, 0.2, 0.4, 0.6, 0.8 on the outer circle; 0.1, 0.3, 0.5, 0.7, 0.9 on the inner circle.

STARBACKGD2

Join the points with reference lines to create the star outline.  The reference lines are used for creating a void extrusion to cut the revolve.

STARBACKGD4

STARBACKGD5

The Star Background is nested to the main family (Shield) which is composed of the Star, the Red Band and the White Band.

The Star

Similar to the construction of the Star Background, the Star is a revolve with a void extrusion of the star background.

STAR

The Red Band

The Red Band is another revolve with a void extrusion to cut it into two red rings.

REDBAND

The White Band

Finally the White Band, another revolve.

WHITEBAND

Method 2: Traditional Family

The Star Outline (Star Leg Line Family)

To make a parametric star outline, create a generic model with model lines only.

STARLEG1

Nest the family to main family (Shield).  Place and array it radially, 5 number in 360 degrees.

STARLEG2

The star outline now can be used to create the Star and the Star Background.  Make all instances of the Star Leg line family invisible.

STARLEG3

The Star Background

The Star Background is a revolve with a void extrusion by picking the lines from the nested and arrayed Star Leg family.

STARBACKGD_TRAD

The Star

The Star is a revolve with a void extrusion with a circle and lines from the nested and arrayed Star Leg family.

STAR_TRAD

The Red Band

The Red Band is another revolve using 2 closed loop boundary lines.

REDBAND_TRAD

The White Band

Finally, the White Band is another revolve.

WHITEBAND_TRAD

Comparing Adaptive Component and Traditional Family

Both methods produce exactly the same geometries as well as parametric capability.

COMPARE_AC_TRAD

This exercise involves a number of revolves in creation of the shield.  Traditional Family method does have advantage over Adaptive Component in the ease of revolve in 2 ways:

  1. Revolve in Traditional Family, having the boundary lines drawn in sketch mode makes modeling much easier than in Adaptive Component in which reference lines have to be drawn before form is created, especially in this case which several geometries have to be created using the same curve.
  2. Revolve in Traditional Family allows more than 1 closed loop boundary lines.

Happy July 4th ****====

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3 responses to “Happy July 4 With Captain America

  1. Pingback: Weekly Roundup – 2015.26 | The BIMsider·

  2. Pingback: Happy July 4 With Captain America - Revit news·

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