Fixed Camera Calibration for Depth Estimation Using Ground Lines
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Solution Overview
Problem
Current driving assistance systems face limitations in accurately estimating depth for various objects, particularly in dense traffic scenarios, due to the reliance on range-specific proximity sensors and the need for known object dimensions, which can lead to inefficiencies and increased costs.
Innovation Solution
A method and system for calibrating a fixed image-capturing device to estimate distances of objects from a vehicle using pixel rows corresponding to calibration lines on a ground plane, eliminating the need for known object dimensions and improving accuracy through line correspondences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proximity sensors are used to estimate distances of near-by objects, then distance estimation capability is provided, but the system requires multiple sensors to ensure entire coverage which increases cost and complexity
Solution Approach 1:
The patent applies universality by making a single image-capturing device perform multiple functions: it captures images for object detection, estimates distances through calibration with calibration lines, and provides entire coverage of the vehicle's path. This eliminates the need for multiple specialized proximity sensors while maintaining comprehensive monitoring capability.
Solution Approach 2:
The patent uses calibration lines (physical copies/reference objects) placed on the ground to create a mapping relationship between image coordinates and real-world distances. By capturing images of these known calibration lines and establishing correspondences, the system can estimate distances of actual objects without requiring multiple physical sensors.
2Device complexity
If a single image-capturing device is used to estimate distances, then cost and complexity are reduced, but accurate depth estimation requires known object dimensions which may not be available
Solution Approach 1:
The patent introduces calibration lines as intermediary reference objects placed on the ground between the image-capturing device and the actual objects of interest. These calibration lines with known dimensions serve as mediators to establish the mapping relationship between pixel coordinates and real-world distances, enabling accurate depth estimation without needing to know the dimensions of actual objects.
Solution Approach 2:
The patent performs preliminary calibration by capturing images of calibration lines with known dimensions before estimating distances of actual objects. This preliminary action establishes the necessary mapping parameters and calibration data that enable subsequent distance estimations to be accurate even when object dimensions are unknown.
3Measurement precision
If conventional camera-based distance estimation is used with known object dimensions, then distance can be estimated, but this approach is not feasible when actual dimensions of objects are unknown
Solution Approach 1:
The calibration lines act as universal intermediaries that provide a reference framework applicable to all objects in the scene. By establishing the mapping between image space and real-world space through these intermediary calibration lines, the system can estimate distances of any object regardless of whether its actual dimensions are known, thereby improving adaptability.
Data Source
AI summary
Calibration and distance prediction for driving assistance is provided. A camera of a vehicle is calibrated to obtain a distance data set. The distance data set includes a distance of each row of pixels of a first image captured by the camera. The distance data set may be further utilized in real-time to predict a distance of an object from the vehicle. Based on the predicted distance, a warning message for an impending collision may be generated and communicated to a driver of the vehicle, thereby facilitating driving assistance to the driver in the real-time.