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.
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.
|
ImageHeight (input_object) |
image(-array) -> object : byte / int4 / real |
| Height field to be shaded. | |
|
ImageShade (output_object) |
image(-array) -> object : byte |
| Shaded image. | |
|
Slant (input_control) |
angle.deg -> real / integer |
| 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 -> 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 | |
| Typical 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 | |
| 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 -> real / integer |
| 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 -> string |
| Should shadows be calculated? | |
| Default value: 'false' | |
| Suggested values: 'true', 'false' | |
If all parameters are correct shade_height_field returns the value 2 (H_MSG_TRUE). Otherwise, an exception is raised.
shade_height_field is reentrant and automatically parallelized (on tuple level).
sfs_mod_lr, sfs_orig_lr, sfs_pentland, phot_stereo
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