Visual appearance: Difference between revisions

Revision as of 14:25, 21 June 2023

Latest revision as of 01:28, 14 November 2024

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{{Technical|date=February 2010}}

The '''visual appearance''' of objects is given by the way in which they [[Reflection (physics)|reflect]] and transmit [[light]]. The [[color]] of objects is determined by the parts of the [[spectrum]] of (incident white) light that are reflected or transmitted without being absorbed. Additional appearance attributes are based on the directional distribution of reflected ([[BRDF]]) or transmitted light (BTDF) described by attributes like [[Gloss (material appearance)|glossy]], shiny versus dull, matte, clear, [[turbidity|turbid]], distinct, etc. Since "visual appearance" is a general concept that includes also various other visual phenomena, such as color, visual texture, visual perception of shape, size, etc., the specific aspects related to how humans see different ''spatial'' distributions of light (absorbed, transmitted and reflected, either regularly or diffusely) have been given the name ''[[Cesia (visual appearance)|cesia]]''. It marks a difference (but also a relationship) with color, which could be defined as the sensation arisedarising from different ''spectral'' compositions or distributions of light.

==Appearance of reflective objects==

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* '''[[Lambertian reflectance|Lambertian reflection]]''': this type of reflection represents an extreme case, since all incident light is scattered into the hemisphere above the surface with the radiance being the same for all directions (isotropic directional distribution). Plain white paper for photocopiers or printers is a good example for a [[Diffuse reflection|Lambertian diffuse reflector]].

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|colspan="3" align="left"|'''Figures 2''': Illustration of the basic types of reflection – specular (mirror like, left), haze (center) and [[Diffuse reflection|Lambertian diffuse]] (right). The geometry is shown in the upper part, the intensity versus angle of inclination of a detector is shown in the lower part of the diagrams.'''

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