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Colour Display Techniques
Additive Colours
Subtractive Colours
Colour Triangle
Colour Cubes
Hexagon
Hexcone
Hue, Intensity and Saturation
Chromo-Stereoscopy
Colour mix
Additive Primaries:
Red, Green and Blue
Subtractive Primaries:
Yellow, Magenta and Cyan
The colour of an object is defined by the colour of light that it reflects.
Colour Cube
L & K 10.7
Hexagon
A hexagon is formed by the interception of the plane of
projection with all six sides of the colour cube
R
M
Hexagon
Y
B
G
C
Perpendicular to the gray line
Hexcone
Hexcone: When the plane of projection is moved from
the white to black along the gray line, successively
smaller colour subcubes are intercepted and a series of
hexagons of decreasing size are produced. The hexagon
at white is the largest and the hexagon at black is reduced
to a point. This series of hexagons define a solid called the
hexcone
Hue: the angle around the hexagon. It gives the dominant color
Intensity: the distance from the zero intensity point along the
gray line. It defines the brightness of a color
Saturation: the distance from the gray point at the centre a
of the hexagon. It reveals the purity of a color
RGB to HIS transformation
R
I
G
H
B
S
Chromo-Stereoscopy
red
green
blue
Refraction index
Depth perception can be created using a pair of glasses which
have different refraction indices for different colours. Digital
Elevation models (DEM) can be assigned with different colours
to create depth perception.
wavelength
Chromo-Stereoscopy
Example:
Hue
DEM, For depth perception
Intensity TM for surface brightness
Saturation SAR for surface texture (terrain shadows, forest roughness)
This is a perfect combination to show the topography,
surface features and natural shadows in one image
Chromo-Stereoscopy
Example II:
Hue
DEM, for depth perception
Intensity TM for surface brightness
Saturation constant
This combination is useful when only DEM and optical data
are available. Surface features and terrain relief are shown
very well using this combination
Chromo-Stereoscopy
Example III:
Hue
DEM, for depth perception
Intensity SAR
Saturation constant
This combination is useful to show terrain relief and shadows