3D Scanner Camera Rotation for Colorized Point Clouds
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Solution Overview
Problem
Existing 3D scanning technologies face challenges in efficiently capturing colorized point clouds due to limited field of view, high number of snapshots required, and parallax errors associated with off-axis camera placement.
Innovation Solution
A device comprising a base, an alidade rotatably mounted on the base, an electronic distance meter, at least one camera, and a control unit that controls the rotation of the alidade and the generation of a point cloud, allowing for simultaneous acquisition of a point cloud and image capture with cameras oriented to minimize parallax errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single coaxial camera is placed in the central obscuration of the receiving optics, then image quality and centering are improved, but the field of view is limited and requires a high number of snapshots
Solution Approach 1:
The patent divides the imaging function into multiple off-axis cameras positioned at different locations around the electronic distance meter. Each camera captures a specific angular range, and together they cover the complete 360-degree horizontal field of view, eliminating the need for multiple snapshots while maintaining image quality.
Solution Approach 2:
The patent transitions from a single-axis coaxial camera arrangement to a multi-dimensional off-axis camera configuration. Cameras are positioned at different radial distances and angular positions around the electronic distance meter, creating a three-dimensional arrangement that expands the horizontal field of view without compromising vertical field of view or image quality.
2Productivity
If images are captured during scanning, then acquisition time is reduced, but images become blurred due to rotational movement
Solution Approach 1:
The patent implements a dynamic compensation mechanism where the camera system rotates in opposition to the alidade's rotation. This dynamic adjustment maintains a stable relative position between the cameras and the external environment during scanning, preventing image blur while enabling continuous acquisition throughout the scanning process.
Solution Approach 2:
The patent applies preliminary anti-action by pre-positioning the cameras on rotatable platforms and configuring them to rotate in the opposite direction to the alidade before scanning begins. This anticipatory counter-rotation ensures that the cameras remain stationary relative to the external environment throughout the scanning process, eliminating blur caused by rotational movement.
3Area of stationary object
If off-axis cameras are used to expand field of view, then more snapshots can be captured simultaneously, but parallax errors are introduced
Solution Approach 1:
The patent incorporates feedback mechanisms through precise control units that monitor and adjust camera positions and orientations. The control unit compensates for parallax errors by calculating correction factors based on camera positions and applying real-time adjustments to ensure accurate 3D reconstruction from the captured images.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient generation of colorized point clouds with improved field of view and reduced need for multiple passes, facilitating faster data acquisition and accurate image reconstruction.
Implementation Method 1
A time-of-flight 3D scanner includes a laser range finder that calculates the distance to a reflecting point by measuring the time it takes for a laser pulse to do the round trip. Since the speed of light c is known, the round-trip time determines the travel distance of the laser pulse
Implementation Method 2
the off-axis placement of the cameras induces parallax errors that must be compensated and make reconstruction difficult
Data Source
AI summary
The invention relates to a device comprising an alidade rotatably mounted on a base about a vertical axis and to which are attached an electronic distance meter having a horizontal axis and arranged to generate a point cloud, and at least one camera oriented towards an optical system housed in the alidade. Each camera is positioned so that the virtual image of its image nodal point is at the intersection of the vertical and optical axes, and is attached to a platform rotatably mounted about an axis colinear with the vertical axis and passing through the image nodal point. In the scanning mode, each platform rotates at an angular velocity opposite to that of the alidade over a plurality of angular ranges to allow each camera to capture images for colorizing the point cloud.