Projector Keystone Correction via RGBD Camera Plane Fitting
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Solution Overview
Problem
Current projector keystone correction methods require complex geometric calculations, making them cumbersome and inefficient for achieving accurate and quick correction of distorted projection images due to environmental factors.
Innovation Solution
A method utilizing a Red, Green, Blue-Depth (RGBD) camera to obtain coordinate values of position points on a projective plane, determining conversion relations between coordinate systems, performing plane fitting, and adjusting the projection optical engine based on included angles to correct keystone distortion without relying on specific patterns or complex calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex geometric calculations are used to obtain deflections of the projectors relative to the projective planes, then keystone correction can be achieved, but the process becomes cumbersome and inefficient
Solution Approach 1:
The patent replaces complex geometric calculation systems with a vision-based system using RGBD cameras. The camera captures images of the projection surface, and through coordinate transformation and plane fitting algorithms, automatically determines the projection plane's orientation and performs keystone correction without requiring complex manual geometric calculations, thus simplifying the overall system while maintaining correction accuracy
Solution Approach 2:
The patent uses RGBD cameras to capture visual copies (images) of the projection surface and extracts positional information from these copies. By processing these visual copies through coordinate transformation and plane fitting, the system obtains the necessary geometric information for keystone correction, replacing direct complex geometric measurement with indirect visual copying and analysis
2Measurement precision
If traditional keystone correction methods are used, then correction can be performed, but the process is time-consuming and not quick enough
Solution Approach 1:
The patent performs preliminary actions by capturing images of the projection surface before actual projection occurs. The RGBD camera captures the projection surface geometry in advance, and the system processes this information through coordinate transformation and plane fitting to pre-determine the correction parameters. This preliminary capture and processing enables quick correction execution without time-consuming calculations during the actual projection adjustment
Solution Approach 2:
The patent establishes a continuous workflow where the RGBD camera continuously captures the projection surface, and the system continuously processes this information through coordinate transformation and plane fitting. This continuous action allows the system to quickly adapt to different projection scenarios without interruption, maintaining correction accuracy while reducing overall correction time through uninterrupted data acquisition and processing
3Measurement precision
If specific patterns are used for keystone correction, then correction can be achieved, but the method becomes vulnerable to occlusion and precision loss
Solution Approach 1:
The patent makes the correction method universal by using RGBD cameras to capture the entire projection surface geometry rather than relying on specific patterns. The camera can detect various features (corners, edges, and other geometric characteristics) on the projection surface, making the system adaptable to different surfaces and patterns while maintaining correction precision. This multi-functional approach allows the system to handle diverse projection scenarios without being vulnerable to occlusion of specific pattern elements
Solution Approach 2:
The patent changes the parameters used for detection from pattern-based recognition to geometric parameter extraction. Instead of relying on specific pattern elements that may be occluded, the system extracts geometric parameters (coordinate values, plane equations, orientation angles) directly from the captured images. This parameter change makes the system more robust to occlusion while maintaining precision, as the geometric parameters can be derived from multiple points and features on the projection surface
Data Source
AI summary
Disclosed is a projector keystone correction method, including: obtaining first coordinate values of a plurality of position points on a projective plane through an RGBD (Red, Green, Blue-Depth) camera in a first coordinate system; determining second coordinate values of the position points according to a predetermined conversion relation and the first coordinate values in a second coordinate system; and using an included angle between a fitted plane obtained by fitting according to the second coordinate values of the plurality of position points and a coordinate plane of the second coordinate system to achieve keystone correction.