Multi-Projector Calibration via Color-Coded Grid Point Synthesis
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Solution Overview
Problem
Conventional multi-projection techniques face challenges in efficiently calibrating and blending images from multiple projectors due to difficulties in accurately positioning cameras, correcting lens distortions, and ensuring high image quality on irregular surfaces, often requiring dedicated equipment and increasing complexity with the number of projectors.
Innovation Solution
A projection system that includes an image preparation unit, grid point extraction unit, grid point transformation unit, grid point synthesis unit, and correction coefficient calculation unit to prepare and correct images for calibration, transform grid points into a common coordinate system, and calculate correction coefficients for each projector, allowing for precise alignment and blending of images across different imaging ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential imaging of reference images from multiple projectors is performed, then position and scale adjustment can be achieved, but a tripod mount is required and convenience is lowered
Solution Approach 1:
The patent replaces the mechanical tripod mount system with a handheld camera approach. The camera is held by an operator to capture projection images from multiple projectors simultaneously, eliminating the need for complex mechanical mounting structures while maintaining calibration accuracy through software-based position and scale adjustment.
Solution Approach 2:
The patent creates a universal calibration method that works with any camera without requiring specialized mounting equipment. The same handheld camera can be used for calibrating multiple projectors in various configurations (side-by-side, stacked, overlapping), making the system adaptable to different installation scenarios without requiring different equipment.
2Loss of time
If simultaneous projection and imaging of reference images from multiple projectors is performed, then calibration time is reduced, but structured patterns from different projectors overlap and cannot be easily separated
Solution Approach 1:
The patent uses color-coded reference images for each projector. Each projector projects a reference image with a distinct color or color range, allowing the camera to capture all projections simultaneously while the image processing software separates and identifies patterns from each projector based on their color characteristics. This enables simultaneous imaging without pattern confusion.
Solution Approach 2:
The patent introduces color information as an intermediary that facilitates the separation of overlapping patterns. The color coding acts as a mediator between the simultaneous projections and the image processing system, enabling automatic identification and separation of patterns from different projectors without requiring sequential imaging.
3Area of stationary object
If divisional imaging is performed with shifted imaging positions, then all projectors can be imaged, but lens distortion correction becomes more complex and work load increases
Solution Approach 1:
The patent implements self-service lens distortion correction by having the camera capture undistorted reference images that include grid patterns or known geometric structures. The software automatically detects these patterns and calculates distortion parameters, then applies correction without requiring manual intervention or complex calibration procedures. The system corrects its own imaging distortions through automated pattern recognition and mathematical transformation.
Solution Approach 2:
The patent performs preliminary distortion correction by capturing reference images with known geometric patterns before the actual calibration process. These reference images are used to pre-calculate distortion correction parameters that are then applied to all subsequent imaging, eliminating the need for complex real-time distortion correction during calibration.
4Measurement precision
If multiple projectors are used for high resolution projection, then image resolution is improved, but the number of calibration operations increases and complexity increases
Solution Approach 1:
The patent merges the calibration process into a single simultaneous operation for all projectors. Instead of calibrating each projector separately, the system captures all projection images at once and performs unified position, scale, and distortion correction for the entire multi-projector system. This combining approach reduces the number of calibration operations from N separate calibrations to one integrated calibration, significantly reducing complexity while maintaining high resolution.
Data Source
AI summary
A projection system for projecting an image onto a projection body by a plurality of projection devices, includes an image preparation unit configured to prepare a plurality of imaging images for calibration, a grid point extraction unit configured to extract a set of grid points that indicates a distortion of a projection image for at least one projection device from each of the plurality of imaging images for calibration, a grid point transformation unit configured to execute a transformation between a plurality of images that are imaged in different imaging ranges on the plurality of imaging images for calibration in such a manner that each set of the grid points that are commonly extracted for a subject projection device is provided in a common coordinate system, a grid point synthesis unit configured to produce a set of the grid points that are synthesized for a subject projection device based on a plurality of sets of the grid points in the common coordinate system, and a correction coefficient calculation unit configured to calculate a correction coefficient for a subject projection device based on a set of the synthesized grid points.