Lidar Tools

This article describes tools from the SMS toolbox that are used to modify and organize lidar data in SMS.

Lidar Tools

LAS to LAS

The Las To Las tool filters and modifies points in LIDAR files. It can clip points to a rectangle or circle, clip them to a range of heights, drop returns and classifications, and set the classification of all points.

Input Parameters

• Lidar file to process – A LIDAR file containing LIDAR data.
• Clip points to a rectangle – Discard all points outside of a rectangle. Enables the following options to define the rectangle:
  • X coordinate of first point on rectangle
  • Y coordinate of first point on rectangle
  • X coordinate of second point on rectangle
  • Y coordinate of second point on rectangle
• Clip points to a circle – Discard all points outside of a circle. Enables the following options to define the circle:
  • X coordinate of center of circle
  • Y coordinate of center of circle
  • Radius of circle
• Clip points to a range of heights – Discard all points outside a range of heights. Enables the following options to define the range:
  • Minimum height
  • Maximum height
• Drop returns – Whether and how to drop returns. Options are:
  • Don't drop returns
  • Keep only first return
  • Keep only last return
  • Drop a list of returns – Enables the following option:
    • List of returns to drop, separated by space – A space-separated list of returns to drop, e.g. "1 2 3" to drop returns 1, 2, and 3. You can also specify just one number to drop only that return.
• Filter points by class – Whether and how to filter points by their classification. Options are:
  • Don't filter classes – No filtering is done.
  • Keep class – Keep only specified classifications. Enables Class to filter/drop option.
  • Drop class – Drop only specified classifications. Enables Class to filter/drop option.
• Class to filter/drop – Space separated list of classes to filter or drop.
• Set classification of points – Whether to set the classification of points in the file. If used, all points in the file will be set to the chosen classification. Enables the following option:
  • Classification to set points to – What classification to set the points to.

Output Parameters

• Output file – Where to write the output file to.

Current Location in Toolbox

Lidar/LAS to LAS

Las To Text

The Las To Text tool converts LIDAR data from the binary LAS and LAZ formats to a standard ASCII format.

Input Parameters

• Lidar file to process – A LIDAR file to convert to text.
• Parse string – Indicates how to parse the file. See #Parse Strings below for more details. Optional. Defaults to xyz.
• Header comment character – If specified, the contents of the LIDAR file's header will be written to the top of the output file, with lines commented out by the chosen comment character. Specify No header to not produce any header.
• Field separator – The character used to separate fields in the text file.

Output Parameters

• Output file – Where to write the output file to.

Parse Strings

Las To Text needs to know what order to write fields into the output file. Parse strings provide that information.

An example parse string:

xyzt

This indicates that the first field on each line is the X coordinate of a point, the second field is the Y coordinate, the third is the Z coordinate, and the fourth is the GPS time. No other fields are produced.

Other supported characters are:

• a – Scan angle.
• B – Blue channel of RGB color.
• c – Classification.
• d – Direction of scan flag.
• e – Edge of flight line flag.
• g – Synthetic flag.
• G – Green channel of RGB color.
• h – Withheld flag.
• i – Intensity.
• I – NIR channel.
• k – Keypoint flag.
• l – Scanner channel.
• n – Number of returns of given pulse.
• o – Overlap flag.
• p – Point source ID.
• r – Return number.
• R – Red channel of RGB color.
• s – Number should be skipped.
• t – GPS time.
• u – User data.
• x – X coordinate of the point.
• y – Y coordinate of the point.
• z – Z coordinate of the point.
• 0 – First additional attribute specified.
• 1 – Second additional attribute specified.
• 2 – Third additional attribute specified.
• 8 – Nineth additional attribute specified.
• 9 – Tenth additional attribute specified.

Current Location in Toolbox

Lidar/LAS To Text

Related Tools

• Text To LAS

LASindex

The LASindex tool creates a spatial index for a given LIDAR file that is used to speed up spatial queries for the file.

The LAS To LAS tool features involving clipping are accelerated by spatial indexes.

Input Parameters

• Lidar file to process – A .las or .laz file to generate a spatial index for.
• Append spatial index to input file – Normally, the index is written to a .lax file with the same name and location as the input. This appends it to the input file instead. Only available for .laz files.

Current Location in Toolbox

Lidar/LASindex

Related Tools

• LAS To LAS

LASInfo

The LASInfo tool prints a LIDAR file's header; a rough approximation of covered area, density, and spacing; the GPS week; and attributes of any points that fall outside the bounding box specified in the LAS header.

This tool does not produce any output files. The report is written to the tool's log instead.

Input Parameters

• Lidar file to process – A LIDAR file to print information for.

Current Location in Toolbox

Lidar/LASInfo

Related Tools

• LAS To Text

LASmerge

The LASmerge tool merges and splits LIDAR files. Using this tool requires having a file that contains a list of the lidar files to be merged. This file typically will need to be created outside of XMS.

Input Parameters

• Lidar file, directory, or text file containing list of files – Clicking the Select File opens a browser where a file can be selected.
  • If a LIDAR file is chosen, just that file will be processed. This is mainly useful when splitting, since otherwise it just copies the file.
  • If a text file is chosen, LASmerge will read it for a list of files to merge. Files should be specified one per line. Paths should be either absolute, or relative to the text file.
• Maximum number of points per output file – If nonzero, LASmerge will split the output so that each file contains at most this many points. The last file may contain fewer than this many points. If zero, LASmerge will merge all the points into a single file, even if the result is extremely large.

Output Parameters

• Directory, filename or file name pattern for output(s) – Where to write the output file(s) to. If splitting, the output will be treated as a pattern, where trailing digits in the file name will be used for a counter, e.g. name00.las will result in files named name00.las, name01.las, name03.las, etc. There must be enough digits in the filename for all of the resulting files, or the remaining ones won't be written. This means that name0.las can only be used for 10 output files and name00.las can be used for up to 100.

Current Location in Toolbox

Lidar/LASmerge

LASzip

The LASzip tool compresses and decompresses LIDAR data.

The tool decides whether to zip or unzip based on the extension of the output file chosen. If it has a .laz extension, then the result will be zipped. Similarly, if the output file has a .las extension, it will be unzipped.

If no output file is specified, then the input file will be used instead. A .txt or .las input will be zipped, and a .las input will be unzipped.

Input Parameters

• Lidar file to process – A file containing LIDAR data. This can be a text file, a .las file, or a .laz file.
• Parse string – Indicates how to parse the file. See #Parse Strings below for more details. Only used when Lidar file to process is a text file.

Output Parameters

• Output name – Where to write the output file to. If left blank, the output file will be placed in the same folder as the input file, with the same name, and an extension chosen depending on whether it was zipped or unzipped.

Parse Strings

LASzip is intelligent enough to handle common field separators inside a text file, but it needs to know what the resulting numbers mean. Parse strings provide that information.

An example parse string: xyzt

This indicates that the first field on each line is the X coordinate of a point, the second field is the Y coordinate, the third is the Z coordinate, and the fourth is the GPS time. Any other fields are discarded.

Other supported characters are:

• a – Scan angle.
• B – Blue channel of RGB color.
• c – Classification.
• d – Direction of scan flag.
• e – Edge of flight line flag.
• g – Synthetic flag.
• G – Green channel of RGB color.
• h – Withheld flag.
• i – Intensity.
• I – NIR channel.
• k – Keypoint flag.
• l – Scanner channel.
• n – Number of returns of given pulse.
• o – Overlap flag.
• p – Point source ID.
• r – Return number.
• R – Red channel of RGB color.
• s – Number should be skipped.
• t – GPS time.
• u – User data.
• x – X coordinate of the point.
• y – Y coordinate of the point.
• z – Z coordinate of the point.
• 0 – First additional attribute specified.
• 1 – Second additional attribute specified.
• 2 – Third additional attribute specified.
• 8 – Nineth additional attribute specified.
• 9 – Tenth additional attribute specified.

Current Location in Toolbox

Lidar/LASzip

Text To Las

The Text To Las tool converts LIDAR data from a standard ASCII format into the more efficient binary LAS and LAZ formats.

Input Parameters

• Text file to process – An ASCII file containing LIDAR data.
• Parse string – Indicates how to parse the file. See #Parse Strings below for more details.

Output Parameters

• Output file – Where to write the output file to.

Parse Strings

Text To Las is intelligent enough to handle common field separators inside a text file, but it needs to know what the resulting numbers mean. Parse strings provide that information.

An example parse string: xyzt

This indicates that the first field on each line is the X coordinate of a point, the second field is the Y coordinate, the third is the Z coordinate, and the fourth is the GPS time. Any other fields are discarded.

Other supported characters are:

• a – Scan angle.
• B – Blue channel of RGB color.
• c – Classification.
• d – Direction of scan flag.
• e – Edge of flight line flag.
• g – Synthetic flag.
• G – Green channel of RGB color.
• h – Withheld flag.
• i – Intensity.
• I – NIR channel.
• k – Keypoint flag.
• l – Scanner channel.
• n – Number of returns of given pulse.
• o – Overlap flag.
• p – Point source ID.
• r – Return number.
• R – Red channel of RGB color.
• s – Number should be skipped.
• t – GPS time.
• u – User data.
• x – X coordinate of the point.
• y – Y coordinate of the point.
• z – Z coordinate of the point.
• 0 – First additional attribute specified.
• 1 – Second additional attribute specified.
• 2 – Third additional attribute specified.
• 8 – Nineth additional attribute specified.
• 9 – Tenth additional attribute specified.

Current Location in Toolbox

Lidar/Text to LAS

Related Tools

• LAS to Text