NAME
vtkLogLookupTable - map scalar values into colors using logarithmic (base 10) color table
SYNOPSIS
#include "/opt/vtk-c++/common/vtkLogLookupTable.h"
class VTK_EXPORT vtkLogLookupTable : public vtkLookupTable
vtkLogLookupTable(int sze=256, int ext=256);
static vtkLogLookupTable *New() {return new vtkLogLookupTable;};
const char *GetClassName() {return "vtkLogLookupTable";};
void PrintSelf(ostream& os, vtkIndent indent);
void SetTableRange(float min, float max);
unsigned char *MapValue(float v);
DESCRIPTION
vtkLogLookupTable is an object that is used by mapper objects to map scalar values into rgba (red-green-blue-alpha transparency) color specification, or rgba into scalar values. The difference between this class and its superclass vtkLookupTable is that this class performs scalar mapping based on a logarithmic lookup process. (Uses log base 10.)
If non-positive ranges are encountered, then they are converted to positive values using absolute value.
vtkLogLookupTable(int sze, int ext):
vtkLookupTable(sze,ext)
Construct with (minimum,maximum) range 1 to 10 (based on logarithmic values).
void SetTableRange(float min, float max)
Set the minimum/maximum scalar values for scalar mapping. Scalar values less than minimum range value are clamped to minimum range value. Scalar values greater than maximum range value are clamped to maximum range value. (The log base 10 of these values is taken and mapping is performed in logarithmic space.)
unsigned char *MapValue(float v)
Given a scalar value v, return an rgba color value from lookup table. Mapping performed log base 10 (negative ranges are converted into positive values).