SWIR Altimeter Using Cross-Correlation Pattern Projection
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Solution Overview
Problem
Conventional radar altimeters for determining altitude above ground level (AGL) are expensive, require valuable space, and can be inaccurate due to signal distortion or interception, necessitating an improved method for reliable AGL measurement.
Innovation Solution
A short wave infrared (SWIR) camera and laser projector system with a pseudo-random, fixed pattern is used, where the image processor controls the timing and repetition of the pattern, enabling scalable resolution and robust height determination through triangulation, utilizing a two-dimensional normalized cross-correlation algorithm to register images and calculate altitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radar altimeters are used to determine altitude, then altitude measurement function is achieved, but the system becomes expensive and requires valuable space
Solution Approach 1:
The patent replaces the conventional radar altimeter system with an optical imaging system using a camera and pattern recognition. This substitution eliminates the need for complex radar hardware while achieving reliable altitude measurement through optical triangulation methods, directly addressing the contradiction between measurement reliability and device complexity
Solution Approach 2:
The patent uses a projected pattern that is captured and processed to create a virtual representation of the ground surface. By analyzing the distortion of this copied pattern in the camera image, the system determines altitude without requiring physical radar components, reducing system complexity while maintaining measurement capability
2Measurement precision
If conventional radar altimeters are used to determine altitude, then altitude measurement function is achieved, but the system becomes inaccurate due to signal distortion or interception
Solution Approach 1:
The patent substitutes radar signal-based measurement with optical pattern-based measurement. By using visible or infrared light patterns instead of radar signals, the system avoids the harmful effects of signal distortion and interception that affect radar altimeters, thereby improving measurement accuracy
Solution Approach 2:
The patent employs patterns with specific optical properties (such as contrast variations or wavelength characteristics) that can be distinguished from ambient light. This allows the system to maintain measurement precision by detecting pattern distortion rather than relying on vulnerable radar signals
3Measurement precision
If a laser projector and camera system is used with pattern projection, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines the laser projector and camera into an integrated altimetry system where both components work together to achieve measurement. By merging these functions into a coordinated system with shared timing and processing control, the patent reduces overall complexity compared to having separate systems, while maintaining high measurement precision through the synergistic operation of pattern projection and optical capture
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 system provides a reliable and accurate method for determining altitude with fewer components susceptible to failure, offering superior resolution and robustness against ambient light variations and pattern corruption, while reducing the need for complex and costly hardware.
Implementation Method 1
projecting a pattern onto a ground from a laser projector and viewing the projected pattern using a camera
Implementation Method 2
enabling scalable resolution and robust height determination through triangulation
Implementation Method 3
utilizing a two-dimensional normalized cross-correlation algorithm to register images and calculate altitude
Data Source
Figure 1
Figure 2~3
AI summary
An altimeter (100) includes a laser projector (104) for projecting a pattern onto a surface and a camera (102) for viewing the projected pattern. An image processor (106) is operatively connected to the laser projector (104) and camera (102) for determining distance to the surface based on cross-correlation of the projected and imaged patterns. The camera can be a short wave infrared (SWIR) camera (102). The projected pattern can be a pseudo-random, fixed pattern.