Multi-Orientation Irradiance Sensing for Drone Image Normalization
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Solution Overview
Problem
Conventional radiometric remote sensing technologies face challenges in accurately estimating incident irradiance from the sun on arbitrary surfaces, particularly on small, rapidly moving platforms like drones, due to difficulties in obtaining precise attitude estimates and the high cost of instruments needed for measuring direct and scattered sunlight components.
Innovation Solution
An irradiance sensing device with multiple photo sensors arranged at different orientations is used to simultaneously sense irradiance components, allowing for the determination of direct and scattered components and incidence angle, which can be used to normalize images acquired by an imaging device on an aerial vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pyrheliometer and pyranometer are used to measure direct and scattered sunlight components, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The single light sensor is segmented into multiple photo sensors arranged at different orientations (e.g., 0°, 45°, 90° angles). Each sensor measures irradiance from a specific direction, and the combined measurements allow separation of direct and scattered sunlight components through computational processing, eliminating the need for complex mechanical segmentation devices like pyrheliometers and pyranometers.
Solution Approach 2:
The mechanical tracking systems and physical shading structures of conventional instruments are replaced with a fixed multi-orientation sensor array combined with computational algorithms. The system uses mathematical processing of simultaneous measurements from multiple fixed sensors to achieve component separation, substituting mechanical complexity with computational simplicity.
2Device complexity
If single light sensor with varied attitude is used to measure both direct and scattered sunlight, then device complexity is reduced, but measurement precision deteriorates due to difficulty in obtaining precise attitude estimates
Solution Approach 1:
Instead of relying on precise attitude measurement of a single sensor, the system segments the measurement function across multiple sensors with fixed, known orientations. This eliminates the need for precise attitude estimation during measurement, as the geometric relationships between sensors are predetermined and stable.
Solution Approach 2:
The sensor orientations are pre-configured at specific angles (e.g., 0°, 45°, 90°) during system design and installation. This preliminary geometric arrangement allows the system to directly compute irradiance components from the measurements without requiring real-time attitude determination, effectively performing the orientation setup in advance.
3Measurement precision
If ground-based calibration systems with reflectance panels are used to normalize light source effects, then measurement precision is improved, but ease of operation deteriorates due to cumbersome setup and inability to measure irradiance simultaneously with images
Solution Approach 1:
The irradiance sensing device is merged with the imaging device into a single integrated system mounted on the aerial vehicle. Both sensors share the same platform and timing, allowing simultaneous measurement of irradiance components and acquisition of target images. This eliminates the need for separate ground-based calibration operations and enables direct computation of reflectance from co-located measurements.
Solution Approach 2:
The system performs its own calibration function through the simultaneous measurements taken by the integrated sensors. The irradiance components measured by the photo sensors directly serve the normalization need of the imaging device, eliminating the requirement for external calibration panels and ground-based reference systems.
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
This approach enables accurate and cost-effective simultaneous measurement of irradiance components, enabling image normalization and compensation for varying light conditions without requiring precise attitude estimates or costly sensors, thus improving the accuracy of multispectral imaging applications.
Implementation Method 1
an irradiance sensing device having a plurality of photo sensors having different orientations
Data Source
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AI summary
The present disclosure is directed to devices and methods for simultaneously sensing irradiance with multiple photo sensors having different orientations, and determining direct and scattered components of the irradiance. One such device includes an aerial vehicle and an irradiance sensing device. The irradiance sensing device includes a base structure mounted to the aerial vehicle, and the base structure including a plurality of surfaces. A plurality of photo sensors are arranged on respective surfaces of the base structure, with each photo sensor having a different orientation.