Using the Simple Wood Model

© 2000 Winston Mitchell

Materials Editor Settings

• Pattern

  Pattern box:

  Simple Wood

  Scale:

  The units here are tenths of a unit per ring. If you are using inches and set Scale to 1, you will get 10 rings per inch. If scale is 10, you will get 1 ring per inch.

  Light & Dark Wood Colors:

  Your choice. Try RGB 250, 200, 100 and RGB 200, 160, 80 for light pine or RGB 100, 50, 25 and 80, 40, 20 for dark mahogany.

  Point on Axis (x, y, z):

  This describes (in drawing units) the position of the center of the log relative to the object being drawn. For this discussion, it is assumed the longest dimension of the object is parallel to the x-axis, the object is being drawn as a solid, and that the drawing units are inches. If another system of units is being used, then the material settings will have to be scaled accordingly. To simulate flat-sawn lumber try putting the center of the log at Z = -8 and so it is not perfectly symmetrical, Y = -1. For quarter-sawn lumber try Y = -8 and Z = -1. For rift-sawn, try Y = -6.4 and Z = -4.9.

  Axis direction (x, y, z):

  This describes the vector that the axis of the log lies on. For the long dimension of the object parallel to the x-axis, try 1, 0.02, 0.02. The resulting 2% skew in Y and Z adds a little interest by running the grain slightly off the part axis.

  Note: when extruding, the z-axis will always lie on the path of extrusion.

  Noise:

  Adds a random element to the grain pattern. A value of 100 will give peak-to-peak noise of about one ring. Try 20.

• Reflectance
  For unfinished wood, try "Matte", 100, 100. Feel free to play with these.

  For finished wood, try the "Mirror" model to get control of the amount of reflection (mirror factor %) and specular light scattering (roughness = 0 or 1 for high gloss more for satin finishes). Try starting with values of 100, 100, 96, 7, 1 (in the order that they appear in the dialog).

• Transparency
  None
• Texture
  (not very noticeable in unfinished wood):
  Try the "Casting" model for its flexibility. This model has two independently configurable surface models. To start with, try these values: 1, 0, 25, 250, 0, 0 (in the order that they appear in the dialog).
• Wrapping
  None.

  Note: most of the sliders have a range of 0 to 100. However, you can input much larger values (up to 9999 in most cases). Also, be aware that the appearance of reflectance and texture settings can change appreciably with different lighting setups and will likely need some adjusting in differing situations.

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The following describes how the following variables affect the materials appearance with respect to rendering methods:

• location when drawn
• movement or rotation after being drawn
• whether the object is a solid or a surface

  CASE 1:

  Preview through Raytrace Full with Solids: "Point on Axis" sets the origin of the material relative the origin of the object's coordinate system (default reference point). "Axis Direction" sets the material's alignment relative to the user coordinate system in effect at the time of creation. Objects drawn with the same dimensions and alignment will appear the same regardless of where in the drawing they are created. If an object is moved or rotated, the material will follow the object and its rotation.

  CASE 2:

  Preview through Raytrace Full, Surfaces: "Point on Axis" sets the origin of the material relative to the origin of the user coordinate system in effect at time of creation. "Axis Direction" sets the material's alignment relative to the user coordinate system in effect at time of creation. The appearance of the material will be a function of where in the drawing an object is created. If an object is moved or rotated, the material will follow the object and its rotation.

  CASE 3:

  Radiosity, Solids and Surfaces: "Point on Axis" and "Axis direction" set the origin and alignment of the material relative the origin of the world coordinate system. The appearance of the material will be a function of where in the drawing an object is created. If an object is moved or rotated, the material will not follow the object or its rotation but will remain fixed relative to the world coordinate system.

Revisions:

12/21/00

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