Dual-Camera Surveying Instrument Target Coordinate Determination
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Solution Overview
Problem
In surveying instruments with cameras, determining target coordinates relative to the instrument's rotation center is challenging when the camera center and rotation center are non-coincident, especially at close ranges due to limitations in signal strength, optical cross-talk, and measurement errors.
Innovation Solution
A method using two cameras with different positions and orientations captures images simultaneously, allowing for the identification of target points in both images and determining coordinates with respect to the rotation center based on camera calibration data, enabling accurate targeting and distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera is used in a surveying instrument, then the device complexity is reduced, but the measurement precision deteriorates when the camera center and rotation center are non-coincident
Solution Approach 1:
The patent divides the camera system into two separate cameras positioned at different locations. The first camera is positioned at the rotation center while the second camera is positioned at a different location. This segmentation allows each camera to capture images from its specific viewpoint, and the system processes both images to determine target coordinates relative to the rotation center, thereby resolving the precision issue without requiring a complex single-camera system with multiple sensors.
Solution Approach 2:
The patent introduces an image processing system that acts as an intermediary between the two cameras and the coordinate determination system. This intermediary processes the images from both cameras, identifies corresponding features, and calculates target coordinates relative to the rotation center. This mediator enables accurate coordinate determination while maintaining relatively simple camera hardware.
2Device complexity
If conventional EDM is used at close ranges (0-25m), then the device complexity is reduced, but the measurement precision deteriorates due to target spot size, low signal strength, optical cross talk, and measurement errors
Solution Approach 1:
The patent merges the dual-camera visual measurement system with conventional EDM technology. The system combines images from two cameras with EDM distance measurements to determine target coordinates. This combination allows the system to use visual data for close-range targeting where EDM has limitations, while still utilizing EDM for distance measurement, thereby achieving accurate measurements at close ranges without significantly increasing overall system complexity.
3Measurement precision
If the camera center and rotation center are made coincident, then the measurement precision improves by eliminating the need for complex coordinate transformations, but the device complexity increases due to mechanical constraints and alignment requirements
Solution Approach 1:
Instead of attempting to mechanically align the camera center with the rotation center (which would increase mechanical complexity), the patent segments the measurement system into two cameras positioned at different locations. One camera is positioned at the rotation center and another at a different position. This segmentation eliminates the need for complex mechanical alignment while the software processes images from both cameras to determine accurate target coordinates relative to the rotation center.
Data Source
AI summary
A method is disclosed for determining coordinates of a target in relation to a surveying instrument wherein a first image is captured using a first camera in a first camera position and orientation, a target is selected by identifying at least one object point in the first image, and first image coordinates of the object point in the first image are measured. In at least one embodiment, a second image is captured using a second camera in a second camera position and orientation, the object point identified in the first image is identified in the second image, and second image coordinates of the object point in the second image are measured. Target coordinates of the target in relation to the rotation center of the surveying instrument are then determined based on the first camera position and orientation, the first image coordinates, the second camera position and orientation, the second image coordinates, and first and second camera calibration data. Furthermore, a surveying instrument for performing the method is disclosed.