SamplePyr

DESCRIPTION

Selects a subset of all of the top-level elements in the pyramid. Outputs a pyramid composed of the selected input elements.

SamplePyr is useful in obtaining a small pyramid from a larger input dataset. This can be an important consideration in initial investigation of a dataset, especially where the input is so large as to impede interactive visualization.

The module functions in several modes. It can sample its input according to an input Boolean selection lattice whose data array causes selection (non-zero) of the element or omission (zero). SamplePyr can sample elements uniformly, striding through the pyramid to achieve the desired number of selections. It can also sample elements randomly according to drand48() (with or without user defined seed), again to achieve the desired number of selections.

INPUTS

Port: Input
Type: Pyramid
Constraints: 1..-layer
Constraints: optional-baseLat
Constraints: n-D compression
Constraints: n-compression type
The input pyramid to be sub-sampled.

Port: Boolean
Type: Lattice
Optional: This port is optional.
Constraints: 1-D
Constraints: 1-vector
The Boolean selection vector governing element sampling.

WIDGETS

Port: Sample Type
Type: Option Menu
Menu Item: Uniform
Menu Item: Random
Menu Item: Random + Seed
Controls whether Uniform, Random, or Random+Seed sampling is done. Deactivated when the Boolean lattice is present.

Port: Num Elements
Type: Slider
Controls the number of elements in the output pyramid. Deactivated when the Boolean lattice is present.

Port: Seed
Type: Text

OUTPUTS

Port: Output
Type: Pyramid
Constraints: 1..-layer
Constraints: optional-baseLat
Constraints: n-D compression
Constraints: n-compression type
The subsampled pyramid composed of selected elements from the input pyramid.

KNOWN PROBLEMS

SEE ALSO

BoundBoxPyr, PyrToGeom.
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© The Numerical Algorithms Group Ltd, Oxford UK. 2000