Calculate light intensity reflected off a local slope of DEM. More...

#include <Hillshade.h>

Collaboration diagram for Isis::Hillshade:

Public Member Functions
	Hillshade ()
	Create a default-constructed Hillshade.

	Hillshade (Angle azimuth, Angle zenith, double resolution)
	Construct and fully initialize a Hillshade.

	Hillshade (const Hillshade &other)
	Copy constructor.

void	setAzimuth (Angle azimuth)
	The azimuth is the direction of the light.

void	setZenith (Angle zenith)
	The zenith is the altitude/solar elevation of the light.

void	setResolution (double resolution)
	The resolution is the meters per pixel of the input to shadedValue().

Angle	azimuth () const
	Get the current azimuth angle.

Angle	zenith () const
	Get the current zenith angle.

double	resolution () const
	Get the current resolution (meters per pixel).

double	shadedValue (Buffer &input) const
	Calculate the shaded value from a 3x3x1 window.

void	swap (Hillshade &other)
	Swap class data with other; this cannot throw an exception.

Hillshade &	operator= (const Hillshade &rhs)
	Assignment operator.

QString	toString () const

Private Attributes
Angle *	m_azimuth
	This is direction of the light, with 0 at north.

Angle *	m_zenith
	This is the altitide of the light, with 0 directly overhead and 90 at the horizon.

double	m_pixelResolution
	meters per pixel

Detailed Description

Calculate light intensity reflected off a local slope of DEM.

This class basically does what the 'shade' application does. This calculates a shaded-relief cube given 3x3 topographic portals. Inputs include the sun angle (azimuth), solar elevation (zenith), and resolution (meters per pixel). This was abstracted out from the shade application, which uses the algorithm described at: http://people.csail.mit.edu/bkph/papers/Hill-Shading.pdf

I (Steven Lambright) took the code, originally authored by Tracie Sucharski, from the shade program and re-implemented it in this class.

This class is re-entrant and const methods are thread-safe.

Author: 2012-10-25 Steven Lambright

History: 2016-11-21 Makayla Shepherd - Corrected the shaded value algorithm in shadedValue. Fixes #4326.

Definition at line 37 of file Hillshade.h.

Constructor & Destructor Documentation

◆ Hillshade() [1/3]

Isis::Hillshade::Hillshade ( )

Create a default-constructed Hillshade.

You must use mutators to initialize this instance before it can be used to calculate shaded values.

Definition at line 24 of file Hillshade.cpp.

References m_azimuth, m_pixelResolution, m_zenith, and Isis::Null.

◆ Hillshade() [2/3]

Isis::Hillshade::Hillshade	(	Angle	azimuth,
		Angle	zenith,
		double	resolution )

Construct and fully initialize a Hillshade.

This can immediately calculate shaded values.

See also: setAzimuth; setZenith; setResolution

Definition at line 38 of file Hillshade.cpp.

References azimuth(), m_azimuth, m_pixelResolution, m_zenith, Isis::Null, resolution(), setAzimuth(), setResolution(), setZenith(), and zenith().

◆ Hillshade() [3/3]

Isis::Hillshade::Hillshade ( const Hillshade & other )

Copy constructor.

Definition at line 52 of file Hillshade.cpp.

References m_azimuth, m_pixelResolution, and m_zenith.

◆ ~Hillshade()

Isis::Hillshade::~Hillshade ( )

Definition at line 65 of file Hillshade.cpp.

Member Function Documentation

◆ azimuth()

Angle Isis::Hillshade::azimuth ( ) const

Get the current azimuth angle.

See also: setAzimuth()

Definition at line 125 of file Hillshade.cpp.

References m_azimuth.

Referenced by Hillshade(), and setAzimuth().

◆ operator=()

Hillshade & Isis::Hillshade::operator= ( const Hillshade & rhs )

Assignment operator.

This utilizes copy-and-swap.

Definition at line 303 of file Hillshade.cpp.

References swap().

◆ resolution()

double Isis::Hillshade::resolution ( ) const

Get the current resolution (meters per pixel).

See also: setResolution()

Definition at line 155 of file Hillshade.cpp.

References m_pixelResolution.

Referenced by Hillshade(), and setResolution().

◆ setAzimuth()

void Isis::Hillshade::setAzimuth ( Angle azimuth )

The azimuth is the direction of the light.

0 is north; this angle rotates the sun.

An invalid angle will silently fail; if shadedValue() is called without a valid azimuth angle then an exception will be thrown.

Definition at line 82 of file Hillshade.cpp.

References azimuth(), Isis::Angle::isValid(), and m_azimuth.

Referenced by Hillshade().

◆ setResolution()

void Isis::Hillshade::setResolution ( double resolution )

The resolution is the meters per pixel of the input to shadedValue().

A special pixel value will silently fail; if shadedValue() is called without a valid resolution angle then an exception will be thrown.

Definition at line 115 of file Hillshade.cpp.

References m_pixelResolution, and resolution().

Referenced by Hillshade().

◆ setZenith()

void Isis::Hillshade::setZenith ( Angle zenith )

The zenith is the altitude/solar elevation of the light.

0 is directly above and 90 is the horizon; this angle raises and lowers the sun.

An invalid angle will silently fail; if shadedValue() is called without a valid zenith angle then an exception will be thrown.

Definition at line 99 of file Hillshade.cpp.

References Isis::Angle::isValid(), m_zenith, and zenith().

Referenced by Hillshade().

◆ shadedValue()

double Isis::Hillshade::shadedValue ( Buffer & input ) const

Calculate the shaded value from a 3x3x1 window.

Definition at line 163 of file Hillshade.cpp.

References Isis::Angle::Degrees, Isis::Angle::fullRotation(), Isis::IsSpecial(), m_azimuth, m_pixelResolution, m_zenith, Isis::Null, Isis::IException::Programmer, Isis::Angle::radians(), Isis::Angle::toString(), and Isis::IException::Unknown.

◆ swap()

void Isis::Hillshade::swap ( Hillshade & other )

Swap class data with other; this cannot throw an exception.

Definition at line 293 of file Hillshade.cpp.

References m_azimuth, m_pixelResolution, and m_zenith.

Referenced by operator=().

◆ zenith()

Angle Isis::Hillshade::zenith ( ) const

Get the current zenith angle.

See also: setZenith()

Definition at line 140 of file Hillshade.cpp.

References m_zenith.

Referenced by Hillshade(), and setZenith().

Member Data Documentation

◆ m_azimuth

Angle* Isis::Hillshade::m_azimuth

private

This is direction of the light, with 0 at north.

Definition at line 61 of file Hillshade.h.

Referenced by azimuth(), Hillshade(), Hillshade(), Hillshade(), setAzimuth(), shadedValue(), and swap().

◆ m_pixelResolution

double Isis::Hillshade::m_pixelResolution

private

meters per pixel

Definition at line 65 of file Hillshade.h.

Referenced by Hillshade(), Hillshade(), Hillshade(), resolution(), setResolution(), shadedValue(), and swap().

◆ m_zenith

Angle* Isis::Hillshade::m_zenith

private

This is the altitide of the light, with 0 directly overhead and 90 at the horizon.

Definition at line 63 of file Hillshade.h.

Referenced by Hillshade(), Hillshade(), Hillshade(), setZenith(), shadedValue(), swap(), and zenith().

The documentation for this class was generated from the following files:

src/base/objs/Hillshade/Hillshade.h
src/base/objs/Hillshade/Hillshade.cpp

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Hillshade() [1/3]

◆ Hillshade() [2/3]

◆ Hillshade() [3/3]

◆ ~Hillshade()

Member Function Documentation

◆ azimuth()

◆ operator=()

◆ resolution()

◆ setAzimuth()

◆ setResolution()

◆ setZenith()

◆ shadedValue()

◆ swap()

◆ zenith()

Member Data Documentation

◆ m_azimuth

◆ m_pixelResolution

◆ m_zenith