What’s This LAS File?

If you’ve been using AutoCAD for a while, you’ve probably encountered files with a .las extension.  AutoCAD uses this extension for its layer state files, which contain saved layer state information exported from a drawing.  With the advent of the new point cloud capabilities within AutoCAD Civil 3D 2010 and AutoCAD Map 3D 2010 (through the Subscription Advantage Pack) and the 2011 releases of these products, there’s a new .las file type you’ll see quite often.  This is a binary file type containing LIDAR data.  The format was developed by the American Society for Photogrammetry and Remote Sensing (ASPRS) in conjunction with a number of industry and government stakeholders.

The LAS file type is a public format allowing the exchange of LIDAR data between the organizations and companies who produce this data and those who consume it. As I mentioned, this is a binary file type created as a public format to provide an alternative to both proprietary storage and interchange formats and the common ASCII file formats used by a wide variety of organizations.  We all know the problems with proprietary formats: data exchange is often complex and prone to difficulties.  ASCII, although simple, can be slow to process due to the very large file sizes involved, even when you are dealing with a small scanned area.  Additionally, some of the LIDAR specific data may be lost, hindering analysis.  Just as landXML, allows us to transfer civil data such as surfaces and alignments simply and without conversion issues, the .LAS format contains LIDAR specific information while still being a relatively easy format to understand.  However, files created in the LAS format are not editable in the same way as landXML files, which are in an ASCII format.

So, remember, there’s now more than one .las file format in the AutoCAD world (actually there’s another that’s used in some well logging applications, but we won’t get into that here).

Until next time. . .

Comments

[George]

Can you tell me what program to use to be able to import a LiDAR LAS file into C3D or how to convert to ASCII file?

[Jeff Morrow]

LAS files are imported using the point cloud object point database, which is an integral part of Civil 3D 2011 and available through the Subscription Advantage Pack in Civil 3D 2010. There is no need to convert the format to ASCII.