Distance-Measurement Camera Defocus Correction for Temporal Errors
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Solution Overview
Problem
Existing ranging cameras based on the pupil division imaging plane phase difference method suffer from temporal ranging errors due to changes in ambient environment and external shocks, which cannot be corrected using conventional methods designed for stereo cameras with fixed baseline lengths.
Innovation Solution
A distance acquisition apparatus that utilizes a combination of stereo ranging calculation, feature point ranging calculation, and correction value calculation to compare first and second distance information, applying structure from motion (SfM) methods and polynomial approximation to correct defocus amounts, thereby reducing temporal ranging errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional stereo camera correction methods are used, then ranging accuracy is maintained for fixed baseline cameras, but the method is inapplicable to ranging cameras with dynamic baseline lengths defined by pupil regions
Solution Approach 1:
The patent changes the correction approach from physical baseline length adjustment to optical parameter adjustment. Instead of correcting based on physical distance changes, the system corrects defocus amounts by calculating ratio data between defocus amounts at different time points, adapting the correction method to the optical characteristics of pupil division imaging plane phase difference ranging cameras.
2Reliability
If no correction is applied, then device complexity is reduced, but temporal ranging errors occur due to ambient environment changes and shocks
Solution Approach 1:
The patent implements a feedback correction mechanism where defocus amounts are continuously measured at different time points, ratio data is calculated based on these measurements, and correction values are applied back to the ranging calculations. This feedback loop compensates for temporal ranging errors caused by environmental changes and shocks.
Solution Approach 2:
The system uses its own defocus amount measurements to generate correction values without requiring external reference systems or additional hardware. The ranging camera performs self-correction by utilizing its captured image data and calculated defocus amounts to compensate for its own temporal errors.
3Measurement precision
If defocus amounts are corrected using SfM and polynomial approximation, then temporal ranging errors are reduced, but calculation complexity increases
Solution Approach 1:
The patent introduces defocus amounts as an intermediary parameter that mediates between the captured images and the final distance measurements. By calculating ratio data based on defocus amounts and using polynomial approximation, the system creates a correction layer that improves measurement accuracy without requiring direct modification of the core ranging algorithm.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
First distance information including an error about a distance between an imaging unit and an object via an optical system is acquired, second distance information including an error that is less than the error included in the first distance information is acquired, based on a ratio between a first defocus amount corresponding to deviation along an optical axis between a sensor plane and an image plane, the first defocus amount having been used for acquisition of the first distance information, and a second defocus amount used for acquisition of the second distance information, a first correction value is generated to correct the first defocus amount and the distance between the imaging unit and the object is calculated by using the first defocus amount corrected with the first correction value.