Image - Relief

Alters image to provide highlighting as though the RGB or RGBa image contains 3D objects illuminated by light from the side. Choose the direction of apparent lighting and then the degree of 3D relief desired.


This command uses the intensity of pixels as an "elevation" value if no other elevation data source is present. For images created from terrains, Relief will use the actual elevation data from the terrain to compute highlights and shading.



Direction toward which light is shining. "South" means it is shining towards the South.


Apparent elevation scale to compute brighter, "lighted" points.


Apparent elevation scale to compute darker, "shaded" points.


Check to see effect in action.



images\img_relief_africa01.gif images\img_relief_africa02.gif


A South-East direction of relief was applied in the example above, so that light is apparently shining from the upper left down towards the lower right.


images\img_relief_eg01.gif images\img_relief_eg02.gif


Moderate amounts of relief will provide useful effects when applied to many aerial photos, especially if the Direction chosen is aligned to the direction of light in the photo. The above example applied a North (upward pointing) direction of light to the image on the right. Since the image already contained visible shadows, a greater degree of Highlights was used than Shadows.




Relief may also be applied to non-geographic images to achieve a wide range of artistic embossing effects. Like all image commands, Relief applies to the entire image unless a selection is in effect, in which case it will apply to the selected pixels only. In the image above we selected a circular group of pixels and then applied Relief to achieve a circular region of embossed appearance.


images\img_relief_eg05.gif images\img_relief_eg04.gif


When applied with restraint, Relief can give "hyper-real" effects to normal photographs, and can bring out hidden detail in geographic images, as seen below:


images\img_relief_eg06.gif images\img_relief_eg07.gif