LAS LiDAR Binary File Description

The ASPRS LiDAR LAS binary file format stores 3D point data. LiDAR stands for Light Detection and Ranging data. This data is generally created by software which combines GPS, IMU, and laser pulse range data to produce X, Y, and Z point data.

 

Click Home | New Map | Specialty | Point Cloud to create a point cloud map with one or more LAS or LAZ files. Click File | Open  or Data | Edit | Merge and select the LAS or LAZ file to view the LAS/LAZ data in the worksheet window.

 

Surfer imports compressed (LAZ) and uncompressed (LAS) LiDAR Binary files.

 

File Format

The format contains binary data consisting of a header block, variable length records, and point data. All data is in little-endian format. The header block consists of a public block followed by variable length records. The public block contains generic data such as point numbers and coordinate bounds. The variable length records contain variable types of data including projection information, metadata, and user application data.

 

Currently, Surfer imports 1.0, 1.1, 1.2, 1.3, and 1.4 format LAS files.

 

Classification Number

The following table lists the LiDAR classification numbers and their colors in the default classification colormap for a point cloud layer.

 

Classification Number

Meaning

Point Cloud Classification Colormap Default Color

0

Created, never classified

Black

1

Unclassified

20% Black

2

Ground

Dark Brown

3

Low Vegetation

Forest Green

4

Medium Vegetation

Dull Green

5

High Vegetation

Spring Green

6

Building

Banana Yellow

7

Low Point (noise)

Light Orange

8

Model Key (Mass) point

Blue Purple

9

Water

Blue

10

Railroad

Purple

11

Road Surface

70% Black

12

Overlap

10% Black

13

Wire - Guard (Shield)

Yellow

14

Wire - Conductor (Phase)

Pale Yellow

15

Transmission Tower

Moon Green

16

Wire - Structure Connector (e.g. Insulator)

Magenta

17

Bridge Deck

Powder Blue

18

High Noise

Red

19-39

Reserved

20% Black

40

Bathymetric Point

Twilight Blue

41

Water Surface

Deep Blue

42

Derived Water Surface

Blue Purple

43

Submerged Oject

Pale Purple

44

IHO S57 Object

Light Violet

45

No Bottom Found Bathymetric Point

Deep Navy Blue

46-255

Reserved

20% Black

 

Return Number

One emitted laser pulse can return to the LiDAR sensor as a single or as many returns. The returns are reflected from objects on or above the ground surface. The first return will be associated with the highest feature, whatever it may be. Intermediate returns may be associated with features such as vegetation. The last return may be associated with the ground but may also be associated with other objects, such as a thick branch. Filtering LAS files by return number can be useful for creating DEMs (digital elevation models), canopy or building height models, or other models.

 

Import Options Dialog

See LiDAR Import Filtering Dialog for opening the LAS/LAZ file in the worksheet or with the Grid Data command.

See Import Points Dialog for creating a point cloud layer.

 

Import Automation Options

See LiDAR Import Automation Options

 

Export Options Dialog

See Export LAS/LAZ

 

Export Automation Options

Surfer does not currently export LiDAR LAS data via automation

 

References:

LAS Specification v1.4 - R13. American Society for Photogrammetry & Remote Sensing. 15 July 2013. http://www.asprs.org/

 

 

See Also

File Format Chart

Import - Worksheet

LiDAR Import Filtering Dialog