Lidar Base Specification: Figures

By NGP Standards and Specifications

Lidar Base Specification 2024 rev. A

Figures from Lidar Base Specification version 1.3 used in LBS 2024 rev. A online

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Lidar Base Specification v. 1.3: Figure 1. Single coverage collection, no overlap. — Lidar Base Specification v. 1.3: Figure 1. Single coverage collection, no overlap. Adjacent swaths (red and yellow) in this example have been collected with insufficient overlap, causing gaps in coverage. The blue areas depict data voids, which are grounds for rejection of the project.

Lidar Base Specification v. 1.3: Figure 2. Designed double coverage collection — Lidar Base Specification v. 1.3: Figure 2. Designed double coverage collection, 50-percent overlap. In this example, three adjacent overlapping swaths (green, red, and yellow) have been collected. Because the design of the project achieved the required aggregate nominal pulse density (ANPD) through double-coverage, the blue areas that are not covered by two swaths are considered data voids, which are grounds for rejection of the project.

Lidar Base Specification v. 1.3: Figure 3. Designed double coverage collection — Lidar Base Specification v. 1.3: Figure 3. Designed double coverage collection, cross-flights with 20-percent overlap. Four overlapping swaths, shown in green, red, cyan, and magenta are shown in this example. The lower cyan swath was erroneously flown too far south, causing the data voids shown in blue. Because the design of the project was to achieve the required aggregate nominal pulse density through cross-flight double-coverage, the blue areas that are not covered by both a horizontal and a vertical swath are considered data voids, which are grounds for rejection of the project.

Example of Lidar project survey point delivery in GeoPackage table. — Figure 4 of the Lidar Base Specification. Example of Survey Point delivery in GeoPackage format for the Lidar Base Specification.

Figure 6 showing an example of a swath separation image. — Figure 5 of the Lidar Base Specification. Example of a Swath Separation Image. Overlapping swath differences were calculated using a TIN algorithm. Point-in-pixel algorithm also okay as long as the spatial resolution is coarse enough to contain at least one point from each swath. Pixel colors are based on swath differences using green for 0 cm to 8 cm, yellow for 8 cm to 16 cm, and red for greater than 16 cm. Continuous RGB values throughout area of overlap make it possible to see patterns in the data. A distinct vertical offset in this dataset is indicated by red pixels in the most central overlap region.