Ground Image Alignment via Warping for Aerial Feature Matching

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Solution Overview

Problem

Existing techniques face challenges in accurately matching features between ground-based images and aerial imagery due to significant differences in camera viewpoints and imaging conditions, making it difficult to determine camera parameters for ground-based images using aerial imagery.

Innovation Solution

A computer-implemented method that involves identifying candidate aerial imagery, transforming ground-based images to a warped image aligned with the aerial imagery using geometric data, and matching features between the warped image and candidate aerial imagery to align the images, allowing for the determination of camera parameters such as pose and geographic position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional feature matching techniques are used between ground-based images and aerial imagery, then the process is simple, but the matching accuracy deteriorates due to large differences in camera viewpoint and imaging conditions

Engineering Contradiction:
Improvefeature matching accuracyVSAvoidimage processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by transforming the ground-based image to a warped image that matches the aerial imagery's viewpoint and imaging conditions before performing feature matching. This preprocessing step eliminates the adverse effects of viewpoint differences and varying imaging conditions, enabling accurate feature matching between the two image types.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If accurate camera parameters are determined for ground-based images using aerial imagery, then the integration quality into geographic information systems improves, but the alignment process becomes more complex

Engineering Contradiction:
Improvecamera parameter accuracyVSAvoidalignment process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses the warped image as an intermediary representation that bridges ground-based images and aerial imagery. By transforming the ground-based image to match the aerial imagery's perspective and conditions, the warped image serves as a common reference frame that facilitates accurate camera parameter determination while simplifying the overall alignment process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2879090B1Aligning ground based images and aerial imagery
Publication Date: 2018.01.31 GOOGLE LLC
  • EP2879090B1 patent drawingFigure 1~2
  • EP2879090B1 patent drawingFigure 3~4
  • EP2879090B1 patent drawingFigure 5

AI summary

Systems and methods for aligning ground based images of a geographic area taken from a perspective at or near ground level and a set of aerial images taken from, for instance, an oblique perspective, are provided. More specifically, candidate aerial imagery can be identified for alignment with the ground based image. Geometric data associated with the ground based image can be obtained and used to warp the ground based image to a perspective associated with the candidate aerial imagery. One or more feature matches between the warped image and the candidate aerial imagery can then be identified using a feature matching technique. The matched features can be used to align the ground based image with the candidate aerial imagery.