Fisheye Camera Object Detection via Reverse Mapping

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Solution Overview

Problem

Fisheye cameras offer a wider field of view but suffer from severe image deformation near the edges, making it difficult to accurately process and analyze images, particularly in intelligent traffic systems where lane lines and vehicle velocities are distorted, leading to discarded edge information.

Innovation Solution

The method involves projecting original images from a fisheye camera onto a cylindrical or spherical projection model, performing reverse mapping to create at least two images with different angles of view, allowing for object detection in both without cutting off edge information, thus fully utilizing the wide field of view.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If fisheye camera is used to capture images, then field of view is widened, but image deformation occurs at edges

Engineering Contradiction:
Improvefield of viewVSAvoidimage deformation
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent divides the fisheye image into multiple regions (central region and edge regions) and processes them differently. The central region is used for normal object detection, while edge regions are processed through reverse mapping to correct deformation, allowing the entire field of view to be utilized effectively.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies reverse mapping to transform the deformed edge regions of the fisheye image back to their original undistorted positions. This inversion process corrects the radial distortion by mapping pixels from the deformed image space back to the undistorted sensor space, enabling accurate object detection in previously unusable edge areas.

Inventive Principle:
Principle #13The other way round (Inversion)

2Loss of information

If edge portion of fisheye image is retained, then wide field of view information is preserved, but object detection accuracy decreases due to deformation

Engineering Contradiction:
Improveedge information retentionVSAvoidobject detection accuracy
Core Design Contradiction:
Loss of informationVSMeasurement precision

Solution Approach 1:

The patent segments the image processing pipeline into different handling methods for central and edge regions. Central region images are processed directly, while edge region images undergo reverse mapping correction before object detection, thus preserving edge information while maintaining detection accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the coordinate system and mapping parameters for edge region processing. By applying reverse mapping transformations that adjust pixel coordinates and spatial relationships, the system corrects deformation effects while retaining the expanded field of view information captured by the fisheye lens.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If conventional cameras are used for traffic surveillance, then image processing is easier, but field of view coverage is limited

Engineering Contradiction:
Improveimage processing easeVSAvoidfield of view coverage
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The patent introduces reverse mapping as an intermediary processing step that bridges fisheye camera capabilities with conventional object detection algorithms. This intermediate transformation layer corrects fisheye distortion effects, allowing standard detection algorithms to work effectively on fisheye-captured images without requiring complete redesign of the processing pipeline.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11398009B2Method and apparatus for performing object detection based on images captured by a fisheye camera and electronic device
Publication Date: 2022.07.26 FUJITSU LTD
  • US11398009B2 patent drawing
  • US11398009B2 patent drawing
  • US11398009B2 patent drawing

AI summary

This disclosure provides an apparatus and method for performing object detection based on images captured by a fisheye camera and an electronic device. The apparatus includes a memory and a processor coupled to the memory. The processor according to an embodiment is configured to: project an original image captured by the fisheye camera onto a cylindrical or spherical projection model, and perform reverse mapping to obtain at least two reversely mapped images, angles of view of the at least two reversely mapped images being towards different directions, detect objects in the reversely mapped images, respectively, and detect an object that is the same among the objects detected in the reversely mapped images. According to this disclosure, information in the wide field of view images obtained by capturing by the fisheye camera may be fully utilized.