CGAL::Classification::Feature::Hsv< GeomTraits, PointRange, ColorMap > Class Template Reference

#include <CGAL/Classification/Feature/Hsv.h>

Inherits from

CGAL::Classification::Feature_base.

Definition

Feature based on HSV colorimetric information.

If the input point cloud has colorimetric information, it can be used for classification purposes. This feature is based on a Gaussian probabilistic model on one of the three HSV channels (hue, saturation or value). It computes the probability of the color of the input point to match this specific color channel defined by a mean and a standard deviation.

The HSV channels are defined this way:

• Hue ranges from 0 to 360 and measures the general "tint" of the color (green, blue, pink, etc.)
• Saturation ranges from 0 to 100 and measures the "strength" of the color (0 is gray and 100 is the fully saturated color)
• Value ranges from 0 to 100 and measures the "brightness" of the color (0 is black and 100 is the fully bright color)

For example, such an feature using the channel 0 (hue) with a mean of 90 (which corresponds to a green hue) can help to identify trees.

Left: input point set with colors. Right: HSV feature on hue with a mean of 90 (from low values in white to high values in dark red).

Its default name is the channel followed by the mean value (for example: "hue_180", "saturation_20" or "value_98").

Note

The user only needs to provide a map to standard (and more common) RGB colors, the conversion to HSV is done internally.

Template Parameters

GeomTraits	model of CGAL Kernel.
PointRange	model of ConstRange. Its iterator type is RandomAccessIterator and its value type is the key type of ColorMap.
ColorMap	model of ReadablePropertyMap whose key type is the value type of the iterator of PointRange and value type is CGAL::Classification::RGB_Color.

Public Types
enum	Channel { HUE = 0, SATURATION = 1, VALUE = 2 }
	Selected channel. More...

Public Member Functions
	Hsv (const PointRange &input, ColorMap color_map, Channel channel, float mean, float sd)
	Constructs a feature based on the given color channel, mean and standard deviation. More...
Public Member Functions inherited from CGAL::Classification::Feature_base
const std::string &	name () const
	Returns the name of the feature (initialized to abstract_feature for Feature_base).
void	set_name (const std::string &name)
	Changes the name of the feature.
virtual float	value (std::size_t index)=0
	Returns the value taken by the feature for at the item for the item at position index. More...

Member Enumeration Documentation

Channel

template<typename GeomTraits , typename PointRange , typename ColorMap >

enum CGAL::Classification::Feature::Hsv::Channel

Selected channel.

Enumerator
HUE	0
SATURATION	1
VALUE	2

Constructor & Destructor Documentation

Hsv()

template<typename GeomTraits , typename PointRange , typename ColorMap >

CGAL::Classification::Feature::Hsv< GeomTraits, PointRange, ColorMap >::Hsv	(	const PointRange &	input,
		ColorMap	color_map,
		Channel	channel,
		float	mean,
		float	sd
	)

Constructs a feature based on the given color channel, mean and standard deviation.

Parameters

input	point range.
color_map	property map to access the colors of the input points.
channel	chosen HSV channel.
mean	mean value of the specified channel.
sd	standard deviation of the specified channel.