Photometric Stereo Reconstruction Invalid Pixel Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photometric stereo systems face challenges due to noise and artifacts caused by imprecision in light direction, camera noise, and non-uniform reflectivity, leading to incorrect detection of surface changes.
Innovation Solution
The use of pairs of light sources to illuminate an object, capturing corresponding images, and processing them to identify and correct invalid pixels, thereby reducing artifacts in photometric stereo reconstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photometric stereo techniques are used to reconstruct surface information, then 3-D reconstruction and surface property detection are achieved, but noise and artifacts cause incorrect detection of surface changes
Solution Approach 1:
The patent applies feedback by using the photometric stereo reconstruction results to identify invalid pixels, then using this identification to correct the reconstruction. The system continuously refines the reconstruction by feeding back the identified invalid pixel locations to adjust and correct the overall reconstruction, thereby improving both measurement precision and detection reliability
Solution Approach 2:
The patent converts the harmful effect of invalid pixels causing artifacts into a benefit by using these artifacts as indicators to identify invalid pixel locations. The system leverages the presence of artifacts to detect and correct problematic areas, transforming the harm of noise and artifacts into a useful mechanism for improving reconstruction quality
2Measurement precision
If multiple images are processed to identify invalid pixels, then reconstruction quality is improved, but processing complexity increases
Solution Approach 1:
The patent segments the image processing into distinct stages: initial photometric stereo reconstruction, invalid pixel identification based on reconstruction artifacts, and selective correction of identified pixels. This segmentation allows the system to process images systematically, improving reconstruction quality while managing processing complexity through structured, modular operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the quality of non-calibrated photometric stereo reconstructions by accurately identifying and addressing invalid pixels, resulting in a more reliable and accurate representation of the object's surface.
Implementation Method 1
Photometric stereo techniques combine the information from multiple images of an object illuminated successively from different directions to 'reconstruct' information on the shape of the object
Data Source
AI summary
A method includes capturing a first image of a surface illuminated from a first direction along an axis by a first light at a first elevation angle with other lights of the illumination system off, and capturing a second image of the surface illuminated from a second direction along the axis by a second light at a second elevation angle with the other lights off, the second direction being opposite the first direction, the second elevation angle being substantially identical to the first elevation angle. The images are processed by taking a derivative of a reflected light intensity at each of a plurality of pixel locations in the images, respectively. The respective derivatives are employed to identify a set of invalid pixels where a photometric stereo condition is not satisfied. A photometric stereo reconstruction is generated based on a set of images and the identified set of invalid pixels.