IsosurfacePyr

DESCRIPTION

This module computes an isosurface from a pyramid data structure. An isosurface is a surface of constant value in a 3D scalar field. The algorithm used takes edge intersections and knits them into triangle meshes for rendering. The values used to define the scalar field are taken from the lowest level of the pyramid (points or vertices layer). The output is a geometry data structure describing the isosurface.

INPUTS

Port: Input
Type: Pyramid
Constraints: 3..-layer
Constraints: 1..-baseLat
Constraints: n-D compression
Constraints: n-compression type
This is the input pyramid from which to calculate an isosurface.

WIDGETS

Port: Threshold
Type: Dial
This is the isosurface threshold value.

Port: Surface Variable
Type: Slider
This parameter controls which channel of the base lattice to test against the isosurface threshold. This widget is initially hidden.

Port: Smooth?
Type: Option Menu
Menu Item: Off
Menu Item: On
Turn gradient shading on and off.

Port: Flip Normal?
Type: Option Menu
Menu Item: No
Menu Item: Yes
This parameter reverses the normals applied to the isosurface to allow lighting of either side of the isosurface on machines that do not support two-sided lighting

OUTPUTS

Port: Surface
Type: Geometry
This is the isosurface output as geometry.

PROBLEMS

Input pyramids must have shared edges within an element, i.e. each edge referenced within a single element must be unique. It is permitted to have redundant edges for different elements. This module can produce surfaces with holes. Calculation of gradients can be slow but is only done when the pyramid or data channel is changed.

SEE ALSO

IsosurfaceLat
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© The Numerical Algorithms Group Ltd, Oxford UK. 1999

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