Light Source Position Estimation via Specular Profile Analysis
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Solution Overview
Problem
Current image processing techniques require capturing an image of the light source to estimate its characteristics and reflectance properties, which is not always feasible or necessary.
Innovation Solution
A method and apparatus that determine intensity profiles in a scene, separate constant and variable intensity profiles, estimate diffuse reflectance, derive specular parameters, and calculate light source direction to estimate the position of the light source without needing a dedicated light source image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source image is captured to estimate light source characteristics and reflectance properties, then measurement precision is improved, but device complexity and ease of operation deteriorate due to requiring additional imaging capability
Solution Approach 1:
The patent extracts only the necessary information (light source characteristics and reflectance properties) from the scene image data without requiring a separate dedicated light source image. The processing system separates and utilizes specific features from the captured scene to estimate the required parameters, eliminating the need for additional imaging operations.
Solution Approach 2:
The imaging system performs multiple functions using the same captured scene image: it simultaneously captures scene geometry, identifies light source positions, estimates light source characteristics, and determines reflectance properties. This multi-functional approach eliminates the need for separate light source imaging while maintaining measurement precision.
2Measurement precision
If a separate light source image is captured to estimate light source characteristics, then measurement precision is improved, but loss of time increases due to additional capture step
Solution Approach 1:
The system performs preliminary analysis of the scene image to identify potential light source regions and characteristics during the initial image capture phase. By pre-processing the scene image data to extract light source information, the system eliminates the need for subsequent separate light source imaging operations, saving time while maintaining estimation accuracy.
Solution Approach 2:
The processing system continuously analyzes the captured scene image data to extract light source characteristics and reflectance properties in a single unified operation. This continuous processing approach maintains measurement precision while eliminating time losses associated with separate capture steps.
3Measurement precision
If light source image capture is required for reflectance estimation, then measurement precision is improved, but device complexity increases due to additional imaging requirements
Solution Approach 1:
The imaging system is designed to perform multiple functions with a single device: capturing scene geometry, identifying light sources, and estimating reflectance properties all from the same scene image. This universal approach maintains measurement precision for reflectance estimation while avoiding the complexity of additional dedicated imaging devices.
Solution Approach 2:
The patent merges the functions of light source characterization and reflectance estimation into a single processing pipeline that operates on the captured scene image. By combining these functions and processing them together from the same data source, the system maintains accuracy while reducing overall device complexity.
Data Source
AI summary
A method, apparatus and system for estimating reflectance parameters and a position of the light source(s) of specular reflections of a scene include RGB sequence analysis with measured geometry in order to estimate specular reflectance parameters of an observed 3D scene. Embodiments include pixel-based image registration from which profiles of 3D scene points image intensities over the sequence are estimated. A profile is attached to a 3D point and to the set of pixels that display its intensity in the registered sequence. Subsequently, distinction is made between variable profiles that reveal specular effects and constant profiles that show diffuse reflections only. Then, for each variable profile diffuse reflectance is estimated and subtracted from the intensity profile to deduce the specular profile and the specular parameters are estimated for each observed 3D point. Then, the location of at least one light source responsible for the specular effects is estimated. Optionally, the parameters can be iteratively refined to determine color information and specular reflectance parameters.