Projector Distortion Correction Using Mobile Camera Reference Patterns
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Solution Overview
Problem
Existing techniques struggle to accurately correct geometric distortion in projected videos when the projection plane has minute concavities and convexities, as they require multiple camera shots with potentially shaky smartphones, leading to incorrect shape detection.
Innovation Solution
A display system comprising a projector and a mobile terminal that generates and projects measurement patterns with a common pattern for reference, allowing the mobile terminal to photograph and correct distortion by compensating for image position changes, enabling high-accuracy distortion correction without the need for fixed camera setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple correction videos with different marker fineness are projected and photographed by a smartphone camera, then the shape of projection plane with minute concavities and convexities can be detected, but camera shake causes position changes in photographed videos leading to incorrect shape detection
Solution Approach 1:
A common pattern is introduced as an intermediary reference element that appears in all measurement patterns. This common pattern serves as a stable reference point that is unaffected by camera shake, allowing the system to reliably detect the positions of measurement markers even when the smartphone camera moves during photographing.
Solution Approach 2:
The system preemptively counteracts the harmful effect of camera shake by incorporating a common pattern that remains stable across all photographs. This common pattern is designed in advance to provide a reference that compensates for position changes, thereby preventing camera shake from causing incorrect shape detection.
2Ease of operation
If markers are displayed at four points on a screen to detect and correct distortion, then trapezoidal distortion can be corrected, but the shape of projection plane with minute concavities and convexities cannot be detected
Solution Approach 1:
The projection plane is divided into multiple measurement regions, each containing measurement markers. By segmenting the detection task into multiple local measurements across different regions, the system can capture the overall shape including minute concavities and convexities that would be missed by simple four-point detection.
Solution Approach 2:
Measurement markers are designed with distinct visual characteristics (such as color or pattern differences) that enable automatic detection and identification. This visual differentiation allows the system to precisely locate markers and calculate distortion coefficients even on projection planes with complex surface variations.
3Reliability
If a fixed camera setup is used to photograph measurement patterns, then image position stability is improved, but additional stabilization tools and increased device complexity are required
Solution Approach 1:
The common pattern acts as an intermediary reference that eliminates the need for fixed camera setups or additional stabilization tools. By providing a stable reference point within the image itself, the system achieves reliable position detection using only the mobile terminal's camera, thereby maintaining simplicity while improving reliability.
Data Source
AI summary
A display system includes: a video display apparatus; and a mobile terminal that communicate with each other. The video display apparatus includes: a measurement pattern generator that generates a plurality of measurement patterns; a projection unit that projects the measurement patterns; a first transceiver that communicates with the mobile terminal to receive information regarding distortion correction of video; and a distortion corrector that corrects the distortion. The mobile terminal includes: a camera unit that photographs the projected measurement patterns; a controller that generates the distortion correction information based on the photographed measurement patterns; and a second transceiver that communicates with the first transceiver to transmit the distortion correction information to the video display apparatus. The measurement pattern generator adds a common pattern to each measurement pattern, which indicates a reference position of each of the measurement patterns. The controller generates the distortion correction information based on the common pattern.