Normalography: A Novel Imaging Technique for Visualizing Pixel-Wise Surface Normal Distributions

Area of Science:

• Optics and Photonics
• Materials Science
• Industrial Manufacturing

Background:

• Surface quality is crucial for product performance, driving demand for real-time inspection.
• Conventional surface normal measurement methods are too slow for high-speed industrial applications.

Purpose of the Study:

• To develop a novel imaging technique for real-time, pixel-wise surface normal distribution visualization.
• To enable high-speed online surface inspection and quality monitoring.

Main Methods:

• Developed normalography, an imaging technique based on reflectance measurements.
• Utilized a multi-angle collimator for simultaneous multi-directional illumination.
• Employed multispectral and RGB illumination for single-shot data acquisition.
• Designed an imaging system for 1024 × 1024-pixel field of view surface normal mapping.

Main Results:

• Achieved real-time visualization of surface normal distributions.
• Enabled single-shot acquisition of surface normal information.
• Demonstrated suitability for highly glossy and smooth surfaces.
• Validated the potential for online industrial surface inspection.

Conclusions:

• Normalography overcomes limitations of conventional methods for real-time surface inspection.
• The technique offers a new approach for quality monitoring in industrial manufacturing.
• Normalography provides camera-like visualization of surface normals without sequential acquisition.