shade_height_field ( ImageHeight : ImageShade : Slant, Tilt, Albedo, Ambient, Shadows : )

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) -> object
Height field to be shaded.

ImageShade (output_object)
image(-array) -> object
Shaded image.

Slant (input_control)
angle.deg -> real / integer
Angle of 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
Range of values: 0.0 <= Slant <= 180.0 (lin)
Minimum increment: 0.01
Recommended increment: 10.0

Tilt (input_control)
angle.deg -> real / integer
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
Range of values: 0.0 <= Tilt <= 360.0 (lin)
Minimum increment: 0.01
Recommended increment: 10.0

Albedo (input_control)
number -> real / integer
Amount of light reflected by the surface.
Default value: 1.0
Suggested values: 0.1, 0.5, 1.0, 5.0
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 -> real / integer
Amount of ambient light.
Default value: 0.0
Suggested values: 0.1, 0.5, 1.0
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 -> string
Should shadows be calculated?
Default value: 'false'
Suggested values: 'true', 'false'


Result

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


Possible Predecessors

sfs_mod_lr, sfs_orig_lr, sfs_pentland, phot_stereo



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