Multi-Projector Display Calibration Using GPU Frame Buffers

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Solution Overview

Problem

Existing multi-projector display systems face challenges in seamlessly blending overlapping outputs from multiple video projectors, leading to defects such as bright seams, gaps, and curvature distortions in the reconstructed image due to misalignment and differing projector characteristics.

Innovation Solution

A method utilizing a modifiable render buffer and view projection matrices to divide and transform a primary image into secondary images, which are then projected in an overlapping manner by multiple video projectors, ensuring a cohesive and seamless display on a projection screen through calibration data sets and graphics pipeline processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple video projectors are used to create a large virtual desktop display, then the display area and resolution are improved, but alignment errors and overlapping defects occur causing bright seams, gaps, and curvature distortions

Engineering Contradiction:

Improvedisplay areaVSAvoidimage alignment precision

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The system performs preliminary calibration by projecting test patterns and capturing images with a camera to determine geometric transformation parameters before actual display operation. This advance preparation establishes the correction matrices needed to eliminate alignment errors, bright seams, and curvature distortions in the multi-projector display.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces manual mechanical alignment and adjustment of multiple projectors with an automated digital image processing system. The system uses software-based geometric transformation and blending algorithms to correct alignment errors and overlapping defects, eliminating the need for precise mechanical positioning of each projector.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If manual calibration methods are used for multi-projector alignment, then device complexity is reduced, but time consumption and operational difficulty increase

Engineering Contradiction:

Improvecalibration system complexityVSAvoidcalibration time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The calibration system is self-calibrating, automatically determining geometric transformation parameters by projecting test patterns, capturing images with a camera, and computing correction matrices without requiring manual intervention. This self-service approach eliminates time-consuming manual alignment while keeping the system relatively simple.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system changes physical parameters during calibration by projecting test patterns at specific luminance levels and capturing images under controlled conditions. These parameter changes enable automatic determination of geometric transformation parameters, reducing calibration time while maintaining system simplicity.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If overlapping projection regions are used to cover the entire display area, then coverage is improved, but bright seams and non-uniform luminance occur in the overlapping regions

Engineering Contradiction:

Improvecoverage areaVSAvoidluminance uniformity

Core Design Contradiction:

Area of stationary objectVSIllumination intensity

Solution Approach 1:

The system applies local quality by using different blending strategies for different regions of the display. In overlapping regions, it applies luminance correction and blending based on the specific characteristics of each projector and screen region, while non-overlapping regions use direct projection without correction. This localized approach ensures uniform luminance across the entire display area.

Inventive Principle:

Principle #3Local quality

4Manufacturing precision

If geometric transformation is applied to correct curvature distortions, then image accuracy is improved, but processing complexity and computational requirements increase

Engineering Contradiction:

Improveimage reconstruction accuracyVSAvoidprocessing system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system segments the display area into multiple regions corresponding to each projector's coverage, with overlapping transition regions between them. This segmentation allows application of geometric transformation and blending operations on smaller, manageable regions rather than the entire display area, reducing processing complexity while maintaining image reconstruction accuracy.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9035969B2Method for multiple projector display using a GPU frame buffer

Publication Date: 2015.05.19 SEIKO EPSON CORP

AI summary

A primary image is transformed into secondary images for projection, via first and second frame buffers and view projection matrixes. To do so, a first image is loaded into the first frame buffer. A calibration data set, including the view projection matrixes, is loaded into an application. The matrixes are operable to divide and transform a primary image into secondary images that can be projected in an overlapping manner onto a projection screen, providing a corrected reconstruction of the primary image. The first image is rendered from the first frame buffer into the second images, by using the application to apply the calibration data set. The second images are loaded into a second frame buffer, which can be coupled to the video projectors.