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ASPRS Lidar Data Exchange Format (LAS) Writer Parameters

ClosedASPRS LAS Version

This is the version number of the LAS file to be written.

Different LAS versions have support for different components. See Fixed Components below.

Version 1.4 also adds support for having more than 4294967296 points in a file.

Version 1.4 (Legacy-Compatible) writes a 1.4 file that may be compatible with other applications that do not have full 1.4 support. This setting forces use of a "legacy" point format, a GeoTIFF-based coordinate system, and restricts the file to a maximum 4294967296 points.

ClosedCompress Files

This parameter enables or disables compression when writing an LAS file. Compression significantly decreases file size; compressed files are often only 10-20% of the original size. However, compressed files take longer to read than uncompressed files.

Note that compression is currently not supported for some point formats when writing version 1.4 files. To enforce compression when writing a version 1.4 file, set the ASPRS LAS Version to 1.4 (Legacy-Compatible).

This parameter applies only to machines using the Windows operating system.

Fixed Components

Point Cloud Component Data Type Notes
x Int32  
y Int32  
z Int32  
intensity UInt16  
returns UInt8  
number_of_returns UInt8  
scan_direction UInt8  
flight_line_edge UInt8  
classification UInt8  
angle Int8  
file_marker UInt8 Allows for LAS flight-line based files to be combined into single files with more than one flight-line. Only supported in version 1.0.
user_data UInt8 (version 1.0) or UInt16 (version 1.1+)  
point_source_id UInt16 Only supported in version 1.1+
gps_time Real64 Only supported in version 1.1+
color_red UInt8 Only supported in version 1.1+
color_green UInt8 Only supported in version 1.1+
color_blue UInt8 Only supported in version 1.1+
classification_flags UInt8

Indicates special characteristics associated with each point. This is a bit flag with the following values:

  • 0 - synthetic (created by a technique other than LIDAR collection)
  • 1 - key-point (should not be removed by thinning)
  • 2 - withheld (should not be included in processing)
  • 3 - overlap (this point is in the overlap region of two or more swaths)

Only supported in version 1.4.

scanner_channel UInt8 Indicates the channel (scanner head) of a multi-channel system. Only supported in version 1.4.
nir UInt16 The NIR (near infrared) value. Only supported in version 1.4.

Additional User Components

LAS supports storing additional components (not part of the fixed component set) for each point through an "extra bytes" Variable Length Record. The User Components parameter specifies a list of components that should be written for each point.

LAS supports "list" components with up to three elements. To write a list component, add the list suffix {} to the end of a component name. Note that each member of a list component must have the same data type.

You can add, remove, or re-order the list to change the order in which the components are stored in the output dataset.

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