Movable Light Source for BRDF Measurement
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Solution Overview
Problem
Conventional methods for determining the bidirectional reflectance distribution function (BRDF) of a surface require numerous light sources, leading to accuracy issues and complexity, with predetermined light source positions limiting flexibility and increasing computational corrections.
Innovation Solution
A device with a single light source that can be displaced to any location on a hemispherical area, allowing adjustable zenith and azimuth angles, enabling precise measurement of BRDF without the need for multiple light sources and reducing computational corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources are used on a hemispherical frame, then measurement coverage is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple light source functions into a single movable light source that can be positioned at different locations on the hemispherical frame. This single light source replaces what would traditionally require multiple fixed light sources, thereby reducing device complexity while maintaining measurement coverage through positional variation rather than numerical multiplication of components.
Solution Approach 2:
The light source is made movable along the hemispherical frame rather than being fixed at predetermined positions. This dynamic positioning capability allows the single light source to occupy multiple spatial positions sequentially, achieving the same measurement coverage that would require multiple static light sources, thus resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If multiple light sources are used, then measurement coverage is improved, but light source homogeneity deteriorates
Solution Approach 1:
By merging multiple light source functions into a single light source, the patent eliminates the heterogeneity problem inherent in using multiple different light sources. A single light source ensures consistent spectral characteristics, intensity uniformity, and temporal coherence across all measurement positions, thereby improving reliability while maintaining measurement coverage through spatial repositioning.
3Device complexity
If light source positions are predetermined on a hemispherical frame, then device simplicity is maintained, but measurement flexibility deteriorates
Solution Approach 1:
The patent transforms the static, predetermined light source positions into a dynamic system where a single light source can be moved to any position on the hemispherical frame. This dynamic positioning mechanism, while adding some structural elements for movement control, provides superior flexibility compared to predetermined fixed positions, allowing adaptive adjustment of illumination angles and positions to suit different measurement requirements.
4Measurement precision
If multiple light sources are used, then measurement accuracy is improved, but computational correction requirements increase
Solution Approach 1:
By using a single light source instead of multiple light sources, the patent eliminates the need for complex computational corrections that would be required to account for variations between multiple non-homogeneous light sources. The single light source provides consistent illumination characteristics across all positions, significantly reducing the computational burden of correcting for light source heterogeneity while maintaining measurement accuracy.
Data Source
AI summary
A device for determining a bidirectional reflectance distribution function of a subject, including a light source for producing an incident light that is directed onto a subject at a predetermined zenith angle and at a predetermined azimuth angle, an element for displacing the light source at any location on the periphery of a hemispherical area centered on the subject, an element for measuring the bidirectional reflectance distribution function of the subject from one fixed location that is preferably aligned with a normal direction defined by the subject, a control unit adapted to control the element for displacing and/or the element for measuring. The element for displacing includes an arc-shaped arm at one end fixedly connected to the light source and slideably connected to a first support to adjust the zenith angle, and an element for pivoting the first support about the normal direction to permit adjustment of the azimuth angle.