PyrToGeom

DESCRIPTION

This module takes pyramid data and interprets layers as points, edges, polygons, and polyhedra, producing appropriate geometry output. It will take pyramids of any number of layers, displaying up to the first four. 0D display is vertices, 1D is vectors, 2D is polygons, and 3D is external faces (faces belonging to only one polyhedron).

The coordinates of the base lattice are assumed to be in 3D. Extra coordinates will be discarded, and missing coordinates will be supplied as zero.

The Dimension input determines how the pyramid will be displayed. If the dimension requested is higher than the dimensionality of the pyramid, the dimensionality of the pyramid will be used, up to a maximum of 2D. If a dimension greater than two is requested, then only the unshared (i.e., external) faces are displayed.

The geometry can be given colors from the base lattice or from data at the layer being displayed, if any. If an optional colormap is present, the Coloring switch allows passing a channel selected by the component slider through the colormap, or direct interpretation of the lattice data as color. In direct interpretation, a single channel becomes greyscale, two channels map to red and cyan, and three or more channels become RGB with the extra channels ignored.

If an optional transform is fed in, the nodes will be transformed before being output as geometry.

Compressed pyramid data are accepted for input and all levels of compression are processed efficiently.

INPUTS

Port: Input
Type: Pyramid
Constraints: 1..-layer
Constraints: 1..-baseLat
Constraints: n-D compression
Constraints: n-compression type
This is the input pyramid to convert.

Port: Colormap
Type: Lattice
Optional: This port is optional.
Constraints: 1-D
Constraints: 4-vector
Constraints: float
This is an optional colormap. It can be turned on and off with the Coloring input.

Port: Transform
Type: Lattice
Optional: This port is optional.
Constraints: 2-D
Constraints: 1-vector
Constraints: float
This is an optional transformation that will be applied to the node coordinates.

WIDGETS

Port: Dimension
Type: Option Menu
Menu Item: 0
Menu Item: 1
Menu Item: 2
Menu Item: 3
This input chooses the dimensionality of the geometric representation.

0
display vertices
1
display edges
2
display polygons
3
display external (unshared) polygons

Port: Component
Type: Slider
This chooses a channel of the data lattice to which to apply a colormap. This input is ignored if a colormap is not present or colormap application has been deselected.

Port: Coloring
Type: Option Menu
Menu Item: Colormap
Menu Item: R-G-B
Menu Item: Texture
This toggles application of a colormap to the base lattice channel selected by Component. If texture is selected, the data is passed through a texture map to give the appearance of banded contours. This option is only available for data defined on the base lattice.

Port: Level
Type: Radio Box
Menu Item: Vertex Data
Menu Item: Level Data
This option selects whether to color the geometry according to data at the base lattice or data at the layer being displayed, if it exists.

Port: Csize
Type: Slider
If texture mapping is used, the number of color bands is set to 2n colors, where n is the value of the Csize widget. This widget is only visible when texture mapping is in force.

OUTPUTS

Port: Output
Type: Geometry
This is the output geometry.

KNOWN PROBLEMS

Using 2D display on a 4-layer pyramid creates many internal faces that are obscured when rendered. Using 3D display (unshared faces) suppresses creation of goemetry for any face that appears twice. PyrToGeom uses the same code as ExteriorPyr to perform this calculation. If no colormap is present, and texture coloring is selected, it will use a default colormap with a data range of 0.0 to 1.0, which may not coincide with the actual data range.

SEE ALSO

CropPyr, ExteriorPyr, IsosurfacePyr, LatToGeom, LatToPyr, ReadPyr, Render.
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© The Numerical Algorithms Group Ltd, Oxford UK. 2000