Herror ::shade_height_field (
    Hobject ImageHeight,
    Hobject *ImageShade,
    const HTuple &Slant,
    const HTuple &Tilt,
    const HTuple &Albedo,
    const HTuple &Ambient,
    const HTuple &Shadows
)
HImage HImage::ShadeHeightField (
    const HTuple &Slant,
    const HTuple &Tilt,
    const HTuple &Albedo,
    const HTuple &Ambient,
    const HTuple &Shadows
) const
HImageArray HImageArray::ShadeHeightField (
    const HTuple &Slant,
    const HTuple &Tilt,
    const HTuple &Albedo,
    const HTuple &Ambient,
    const HTuple &Shadows
) const

Shade a height field.

::shade_height_field computes a shaded image from the height field ImageHeight as if the image were illuminated by an infinitely far away light source. It is assumed that the surface described by the height field has Lambertian reflection properties determined by Albedo and Ambient. The parameter Shadows determines whether shadows are to be calculated.

Attention

::shade_height_field assumes that the heights are given on a lattice with step width 1. If this is not the case, the heights must be divided by the step width before the call to ::shade_height_field. Otherwise, the derivatives used internally to compute the orientation of the surface will be estimated to steep or too flat. Example: The height field is given on 100*100 points on the square [0,1]*[0,1]. Then the heights must be divided by 1/100 first. A Cartesian coordinate system with the origin in the lower left corner of the image is used internally.

Parameters

ImageHeight (input_object)
 image(-array) -> Hobject: HImage(Array)
Height field to be shaded.

ImageShade (output_object)
 image(-array) -> Hobject * : HImage(Array)
Shaded image.

Slant (input_control)
 angle.deg -> HTuple.double / long
Angle between the light source and the positive z-axis (in degrees).
Default value: 0.0
Suggested values: 1.0, 5.0, 10.0, 20.0, 40.0, 60.0, 90.0
Typical range of values: 0.0 <= Slant <= 180.0 (lin)
Minimum increment: 0.01
Recommended increment: 10.0

Tilt (input_control)
 angle.deg -> HTuple.double / long
Angle between the light source and the x-axis after projection into the xy-plane (in degrees).
Default value: 0.0
Suggested values: 1.0, 5.0, 10.0, 20.0, 40.0, 60.0, 90.0
Typical range of values: 0.0 <= Tilt <= 360.0 (lin)
Minimum increment: 0.01
Recommended increment: 10.0

Albedo (input_control)
 number -> HTuple.double / long
Amount of light reflected by the surface.
Default value: 1.0
Suggested values: 0.1, 0.5, 1.0, 5.0
Typical range of values: 0.0 <= Albedo <= 5.0 (lin)
Minimum increment: 0.01
Recommended increment: 0.1
Restriction: Albedo >= 0.0

Ambient (input_control)
 number -> HTuple.double / long
Amount of ambient light.
Default value: 0.0
Suggested values: 0.1, 0.5, 1.0
Typical range of values: 0.0 <= Ambient <= 1.0 (lin)
Minimum increment: 0.01
Recommended increment: 0.1
Restriction: Ambient >= 0.0

Shadows (input_control)
 string -> HTuple.char *
Should shadows be calculated?
Default value: 'false'
Suggested values: 'true', 'false'

Result

If all parameters are correct ::shade_height_field returns the value H_MSG_TRUE. Otherwise, an exception is raised.

Possible Predecessors

::sfs_mod_lr, ::sfs_orig_lr, ::sfs_pentland, ::phot_stereo

Module

Tools

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