Storing lidar data

Originally, lidar data was only delivered in ASCII format. With the massive size of lidar data collections, a binary format called LAS was soon adopted to manage and standardize the way in which lidar data was organized and disseminated. Now it is quite common to see lidar data represented in LAS. LAS is a more acceptable file format because LAS files contain more information and, being binary, can be read by the importer more efficiently.

LAS is an industry format created and maintained by the American Society for Photogrammetry and Remote Sensing (ASPRS). LAS is a published standard file format for the interchange of lidar data. It maintains specific information related to lidar data. It is a way for vendors and clients to interchange data and maintain all information specific to that data.

Each LAS file contains metadata of the lidar survey in a header block followed by individual records for each laser pulse recorded. The header portion of each LAS file holds attribute information on the lidar survey itself: data extents, flight date, flight time, number of point records, number of points by return, any applied data offset, and any applied scale factor. The following lidar point attributes are maintained for each laser pulse of a LAS file: x,y,z location information, GPS time stamp, intensity, return number, number of returns, point classification values, scan angle, additional RGB values, scan direction, edge of flight line, user data, point source ID and waveform information.

ArcGIS supports lidar data that is provided in either ASCII or LAS file format.

The attribute information is maintained in ArcGIS for further analysis.

The LAS dataset, mosaic dataset, and terrain dataset all support lidar data in LAS format. Only the LAS dataset and mosaic dataset work directly with LAS files, while the terrain dataset requires that LAS files be imported into the geodatabase using multipoint geometry.

The terrain dataset supports lidar data in both ASCII and LAS formats. For more information on how to use ASCII data to build a terrain dataset, see Importing terrain dataset source measurements.

Note:

ArcGIS supports LAS versions 1.0, 1.1, 1.2, and 1.3. The waveform information that is available when using LAS version 1.3 is not supported. Additionally, LAS version 1.4 files that are 1.3 compliant, containing point record formats 0 through 5, are supported. LAS version 1.4 files containing point record formats 6 through 10 are not supported.