Lidar Terrain Mapping Using Intersection Elevation Data
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Solution Overview
Problem
Lidar measurements often fail to accurately represent ground-level elevations in urban areas due to the presence of buildings and trees, which can lead to inaccurate terrain models.
Innovation Solution
The system uses Lidar elevation data from roadway intersections, where tall structures are unlikely, to generate a ground-level terrain elevation model by removing outliers and interpolating elevation values from nearby intersections, allowing for accurate determination of ground-level elevations at any point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Lidar measurements are used to map terrain in urban areas, then high-resolution terrain data can be obtained, but the measurements become inaccurate due to buildings and trees blocking the laser
Solution Approach 1:
The patent extracts only the Lidar measurements taken at roadway intersections from the complete dataset. By selecting measurements at specific locations (intersections) where tall structures are unlikely to exist, the method isolates accurate ground-level elevation data from the noisy urban environment, eliminating the harmful blocking effect without requiring complex processing of all measurements
Solution Approach 2:
The patent applies different processing rules to different locations: measurements at intersections are used directly as ground elevation data, while measurements elsewhere are either ignored or used differently. This local differentiation allows accurate terrain modeling at intersection points without being contaminated by building or tree blocking in other areas
2Area of stationary object
If all Lidar measurements are used to create terrain models, then comprehensive coverage is achieved, but outliers from buildings and trees degrade model accuracy
Solution Approach 1:
The patent extracts and isolates only the reliable measurements at intersections from the comprehensive Lidar dataset. This extraction maintains broad spatial coverage through the network of intersections while filtering out the harmful outliers from buildings and trees that would degrade model accuracy
Solution Approach 2:
The patent segments the terrain modeling process into two distinct parts: (1) collecting comprehensive Lidar data across the entire area, and (2) selectively using only intersection measurements for the actual terrain model. This segmentation allows full coverage data collection while maintaining model accuracy through selective data usage
3Ease of manufacture
If rooftop elevation data is used to represent ground level, then simple processing is achieved, but significant errors occur in urban areas
Solution Approach 1:
The patent introduces roadway intersections as intermediary reference points between the Lidar measurements and the desired ground elevation. These intersections serve as mediating locations where rooftop measurements can be reliably converted to ground level without the complexity of processing every individual building or tree obstruction
Solution Approach 2:
The patent extracts the reliable ground-level reference information from intersection measurements and uses this extracted data to represent ground elevation, avoiding the need to process complex rooftop-to-ground conversions for every building while maintaining accuracy
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 method provides a highly accurate urban terrain model by excluding anomalies and using weighted Lidar elevation values from nearby intersections to estimate ground-level elevations, improving the precision of terrain mapping in urban environments.
Implementation Method 1
Lidar uses ultraviolet, visible, or near-infrared light to image objects... light is reflected via backscattering
Implementation Method 2
different types of scattering can be used for different Lidar applications, most commonly Rayleigh scattering, Mie scattering, Raman scattering, and fluorescence
Implementation Method 3
The ground-level elevation at any point in the mapped area can be determined using the ground-level elevation values for nearby intersections
Data Source
AI summary
Systems and methods for generating ground-level terrain elevation models, preparing vector street data to assist in generating such models, and finding approximate elevation of any point using such terrain models are provided. Lidar data can be analyzed, and Lidar elevation values at roadway/street intersections can be used to determine a model of the ground-level elevation in an area or region. Outliers can be removed. The ground-level elevation at any point in the mapped area can be determined using elevation levels for nearby roadway intersections.