Luminance-Based Measures of Shape and Detail Distinctness of 3D Objects as Important Predictors of Light Modeling Concept. Results of a Full-Scale Study Pairing Proposed Measures with Subjective Responses

Abstract

Nowadays it is very common to discuss the various aspects of lighting within a framework of energy efficiency. In addition, the questions concerning lighting quality and occupants' comfort are another topic for active studies and debates.In the current investigation we tested one aspect of lighting quality-that is, light modeling-with the help of a luminance mapping technique. Here the degree of a 3D object's shape and detail distinctness are associated with modeling quality; that is, directly related to the light modeling concept. The aim of the study was to comprehend whether luminance-based design as a method, most perception oriented among others, could be applicable for the evaluation and prediction of the visibility of the shape and details of real 3D objects observed by people under daylight conditions and, further, to suggest luminance-based measures that can be developed into indicators of shape and details distinctness. Ordinal regression analysis of the survey results paired with several measures based on luminance values was performed. The tested measures were luminance ratio, mean luminance of the object, standard deviation of the luminances of the object, and the ratio between the highest luminance value of the object and mean luminance of the object. Among all of these measures the first three have the strongest correlations with subjective perception of 3D objects' shape and detail distinctness.KEYWORDS high dynamic range images, luminance-based measurements, luminance maps, light modeling, shape and detail distinctness Received

Effects of inter-reflections on the chromatic structure of the light field

“…1 The light density, light flow and light diffuseness form an integrated complete description of the lowest-order properties of the light field distribution in a three-dimensional space, 12 which are directly related to our perceptions of the average illuminance, light direction, diffuseness, flow and zones [13][14][15] and indirectly to our perceptions of space, shape, materials and textures. [16][17][18][19][20][21][22] The light squash and higher-order light-field statistics are directly related to scene cohesion and gist 23 and indirectly to, for instance, material perception. 9,24,25 In natural scenes, the diffuse scattering mode forms a significant contribution to the bidirectional reflectance distribution function (BRDF) of most materials.…”