ASPRS LiDAR Data Exchange Format (LAS) Writer Parameters

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.

This parameter enables or disables compression when writing an LAS file. There are two types of compression:

• LAZ (by LASzip): The output file has an .laz extension
• zLAS (by Esri): The output file has a .zlas extension (Windows only)

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 LAZ 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).

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.

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.

This parameter specifies whether to rearrange point records when applying zLAS compression.

When set to Yes, points are re-ordered to optimize data access and minimize file I/O. This is beneficial when using the compressed LAS data directly.

When applying zLAS compression, the optimizer builds a spatial index to make direct use of the compressed data more efficient. In order to do this, the average point spacing of the data is needed.

This option specifies where that data should be found.

• Scan Points: Scan through point data to calculate an accurate spacing
• From Header: Estimate the spacing based on the extents and number of points. This may be faster but less accurate than Scan Points.
• Specify Value: Explicitly specify the spacing value. Enables the zLAS Point Spacing Value parameter.

This parameter specifies the point spacing for zLAS compression. This is only used when zLAS Point Spacing Source is set to Specify Value.