Digital Elevation Model Adjustment for GPS Road Alignment
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Solution Overview
Problem
Satellite images often contain errors despite orthorectification, which can affect their accuracy for navigation and other applications, necessitating improved methods for correcting these errors.
Innovation Solution
Adjusting a digital elevation model (DEM) based on GPS data collected from vehicles traveling on roads, aligning pixel locations in the satellite image with actual road positions, and applying shifts to rational polynomial coefficients (RPCs) to correct distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If orthorectification is applied to satellite images using DEM data, then geometric accuracy is improved, but residual errors remain that affect navigation precision
Solution Approach 1:
The patent implements feedback by comparing GPS coordinates from vehicles (ground truth) with coordinates derived from satellite image pixels after orthorectification. This comparison generates error measurements that are fed back to adjust and refine the DEM data, creating a closed-loop system that continuously improves accuracy based on actual performance
Solution Approach 2:
The patent changes parameters by adjusting DEM pixel values (elevation data) based on error measurements. By modifying the elevation parameters in the DEM to reduce the discrepancy between GPS-derived coordinates and image coordinates, the system optimizes the orthorectification process to achieve better navigation precision
2Measurement precision
If DEM pixel values are adjusted to improve coordinate alignment, then location accuracy is improved, but the complexity of the correction process increases
Solution Approach 1:
The patent applies local quality by adjusting DEM pixel values specifically in areas where errors are detected, rather than uniformly reprocessing entire datasets. The correction is localized to affected regions based on GPS comparison results, reducing overall processing complexity while maintaining accuracy where it matters most
Solution Approach 2:
The patent performs preliminary action by pre-adjusting DEM pixel values based on anticipated error patterns from GPS comparisons. By proactively correcting DEM data before final image processing, the system simplifies subsequent alignment operations and reduces the complexity of iterative corrections
Data Source
AI summary
A method and system for adjusting a digital elevation model (DEM). A satellite image with one or more roads and the DEM are received. The DEM includes an elevation of each pixel of the satellite image. Recorded GPS data corresponding to the one or more roads is received. A pixel in the satellite image corresponding to the one or more roads is determined. A determination is made as to whether the location of the pixel corresponds to the GPS data. After determining that the location of the pixel does not correspond to the GPS data, a set of pixels is determined in the DEM that surround the pixel. The elevation of each pixel of the set of pixels of the DEM is adjusted so that the location of the pixel in the satellite image corresponds to the one or more roads.