Isoband UCD: color filled contour bands on UCD surfaces
Mike French (Evans & Sutherland)
Name: Isoband UCD
mapper
ucd ucd (scalar node values)
colormap colormap (optional)
levels field 1D uniform scalar float (optional)
contours geometry
colour bands colormap
name type default min max
---- ---- ------- --- ---
Colourmap boolean OFF
Boundary
N integer 10 2 20
A set of contour bands are drawn on the exterior faces of a UCD.
The UCD must have a single scalar component of node data. To extract a
single scalar component of node data from a composite ucd use the
UCD EXTRACT module. There is no module available to extract a scalar
from a vector component of node data.
The data values for the contours are taken from the 'levels' input field.
If this input is not present, then the range of the scalar node data is
divided equally to generate N contour levels. There are always at least
two contour levels, giving at least one bounded band. If the levels are
generated locally then the first and last contour levels are always at
the minimum and maximum data values, so the open bands above and
below the data range will not be seen. If the levels are generated in
an INTERVALS UCD module, the local 'N' control parameter is removed.
If the colour map input is not connected, the contour bands will be
given a default greyscale spectrum. If a colour map is present then
the scalar node data range is mapped on to the colour value range.
Use the COLOR RANGE UCD module to set the colormap lo/hi values
to the UCD min/max values.
If the colour value range has been set using the COLOR RANGE UCD module,
the colormap range and the node data range will match exactly:
the band below the minimum level is given the first colour index;
and the band above the maximum level is given the last colour index.
In general, these underflow/overflow bands will not be visible on the UCD.
If the colour value range is completely within the UCD data range, there
may be duplicated colours at the bottom and top of the range. If the scalar
node data range is completely within the colormap range, the contour
colours will be a restricted subset of the full gamut of colours.
The discretized colour map used for the bands is made available as an
output colormap. This can be displayed using the UCD LEGEND module.
The underflow/overflow band colours are displayed at the ends of this
spectrum even though there will not be any bands with these colours in
the slice. Having such excluded endpoints makes it easy to see when the
data has overrun the available spectrum. The colormap output can have
black lines inserted at the band boundaries to simulate the effect of
the ISOLINE UCD module. These lines are controlled using the
'Colourmap Boundary' boolean parameter.
METHOD & BUGS
See ISOBAND SLICE for details of the contouring method and bugs.
a) colour contour bands: use the COLOR RANGE UCD module to set the colormap
range to match the ucd scalar node data.
READ UCD
|
GENERATE COLORMAP UCD EXTRACT
| |
| .-------------o
| | |
COLOR RANGE UCD |
| |
| UCD CROP
| | |
| .----------'
. | | |
ISOBAND UCD |
| |
`------o
|
GEOMETRY VIEWER
b) black contour lines over coloured isobands: use the COLOR RANGE UCD module
to set the colormap value range; set the contour levels globally using the
INTERVALS UCD module; use the STATISTICS module to provide diagnostics
READ UCD
|
GENERATE COLORMAP UCD EXTRACT
| |
| .-------------o-----------------.
| | | |
COLOR RANGE UCD UCD CROP INTERVALS UCD
| | | |
| .------+---o-----. |
| | | | |
.-----------------o-----------------o
| | | | | . | |
ISOBAND UCD | ISOLINE UCD STATISTICS
| | |
`------o---------'
|
GEOMETRY VIEWER