NGP Standards and Specifications

Lidar Base Specification: Tables

Lidar Base Specification 2021 rev. A

Tables referenced in the Lidar Base Specification 2020 rev. A online

 

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Table 1: Aggregate nominal pulse spacing and density.

Table 2: Relative vertical accuracy for light detection and ranging swath data.

Table 3: Land cover classes.

Table 4: Absolute vertical accuracy for light detection and ranging data and digital elevation models.

Table 5: Minimum light detection and ranging data classification scheme.

Table 6: Minimum digital elevation model cell size.

 

Table 1: Aggregate nominal pulse spacing and density.

Quality level Aggregate nominal pulse spacing (m) Aggregate nominal pulse density (pls/m2)
QL0  ≤0.35 ≥8.0
QL1 ≤0.35 ≥8.0
QL2 ≤0.71 ≥2.0
QL3 ≤1.41 ≥0.5

 

Table 2: Relative vertical accuracy for light detection and ranging swath data.

Quality level Smooth surface repeatability, RMSDz (m) Swath overlap difference, RMSDz, (m)
QL0 ≤0.03 ≤0.04
QL1 ≤0.06 ≤0.08
QL2 ≤0.06 ≤0.08
QL3 ≤0.12 ≤0.16

 

Table 3: Land cover classes.

Class number Land cover class or description Previous reporting group Current reporting group
1 Clear or open, bare earth, low grass; for example, sand, rock, dirt, plowed fields, lawns, golf courses FVA NVA
2 Urban areas; for example, tall, dense man-made structures SVA
3 Tall grass, tall weeds, and crops; for example, hay, corn, and wheat fields SVA VVA
4 Brush lands and short trees; for example, chaparrals, mesquite SVA
5 Forested areas, fully covered by trees; for example, hardwoods, conifers, mixed forests SVA
6 Sawgrass n/a n/a
7 Mangrove and swamps n/a

 

Table 4: Absolute vertical accuracy for light detection and ranging data and digital elevation models.

Quality level RMSEz (nonvegetated) (m) NVA at the 95-percent confidence level (m) VVA at the 95th percentile (m)
QL0 ≤0.050 ≤0.098 ≤0.15
QL1 ≤0.100 ≤0.196 ≤0.30
QL2 ≤0.100 ≤0.196 ≤0.30
QL3 ≤0.200 ≤0.392 ≤0.60

 

Table 5: Minimum light detection and ranging data classification scheme.

Code Description
1 Processed, but unclassified
2 Bare earth
7 Low noise
9 Water
17 Bridge deck
18 High noise
20 Ignored ground (typically breakline proximity)
21 Snow (if present and identifiable)
22 Temporal exclusion (typically nonfavored data in intertidal zones)

 

Table 6: Minimum digital elevation model cell size.

Quality level Minimum cell size (m) Minimum cell size (ft)
QL0 0.5 1
QL1 0.5 1
QL2 1 2
QL3 2 5