Multi-Camera Image Registration Using Temporal Coherence

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Solution Overview

Problem

Achieving precise image registration among multiple cameras, especially when there are geometrical differences due to changes in distance and elevation angles, is challenging, particularly in remote sensing applications using infrared cameras where optical flow assumptions are not valid.

Innovation Solution

The system creates extended mini-frames by stitching together sequential images taken over time, utilizing temporal coherence to increase overlap and ease registration, and employs a rigid model to determine relative positions and rotations of cameras, allowing for accurate alignment even with minimal initial overlap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional image registration methods are used with multiple cameras, then processing power requirements increase, but registration precision deteriorates

Engineering Contradiction:
Improveregistration precisionVSAvoidprocessing power requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the image registration process into multiple segments: first registering images from individual cameras to a common coordinate system, then registering sequences of images from each camera. This segmentation allows complex multi-camera registration to be broken down into simpler single-camera registration tasks, reducing overall computational complexity while maintaining precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary registration of individual cameras to establish their relative positions and orientations before processing the actual image sequences. This preliminary action creates a foundation that simplifies subsequent registration tasks, as the system already knows the spatial relationships between cameras without needing to compute everything from scratch for each image pair.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If geometrical differences due to distance and elevation angle changes are considered, then registration accuracy improves, but computational complexity increases

Engineering Contradiction:
Improveregistration accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent dynamically adjusts the registration process based on changes in distance and elevation angles between frames. Instead of using a fixed registration model, the system adapts to temporal variations in camera geometry, applying different transformation models as needed. This dynamic approach maintains accuracy under varying conditions without requiring a completely complex static solution.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes registration parameters based on the specific geometric conditions of each image pair. When distance and elevation angle changes are significant, the system switches to transformation models that account for these variations. This parameter adaptation allows the system to maintain high accuracy only where needed, reducing overall computational complexity compared to always using the most complex model.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If extended mini-frames are created by stitching sequential images, then overlap increases and registration becomes easier, but processing time increases

Engineering Contradiction:
Improveregistration easeVSAvoidprocessing time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent creates extended mini-frames by stitching together sequential images from each camera before performing the final registration. This preliminary stitching action increases the amount of overlapping information available, making the subsequent registration process easier and more accurate. By preparing this extended data structure in advance, the system can perform simpler, faster registration operations on the enriched data.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous processing of image sequences, creating extended mini-frames as it processes each frame. Rather than batch processing all images at once or stopping between operations, the system continuously stitches and registers images in a flowing manner. This continuous action reduces idle time and keeps the processing pipeline efficient, minimizing total processing time while building up the useful overlap information.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentUS9071819B2System and method for providing temporal-spatial registration of images
Publication Date: 2015.06.30 HARRIS CORP
  • US9071819B2 patent drawing
  • US9071819B2 patent drawing
  • US9071819B2 patent drawing

AI summary

A video imaging system for use with or in a mobile video capturing system (e.g., an airplane or UAV). A multi-camera rig containing a number of cameras (e.g., 4) receives a series of mini-frames (e.g., from respective field steerable mirrors (FSMs)). The mini-frames received by the cameras are supplied to (1) an image registration system that calibrates the system by registering relationships corresponding to the cameras and/or (2) an image processor that processes the mini-frames in real-time to produce a video signal. The cameras can be infra-red (IR) cameras or other electro-optical cameras. By creating a rigid model of the relationships between the mini-frames of the plural cameras, real-time video stitching can be accelerated by reusing the movement relationship of a first mini-frame of a first camera on corresponding mini-frames of the other cameras in the system.