What is LAS?

For those who are new to the topic the wiseGEEK offers a straightforward answer to the question what is the LAS file format. As any experienced user will tell you there is a lot more to understand, but it is a starting point for the novice.

Given the level of interest in the soon to be released LAS 1.4 format this might help some to get up to speed.

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1 Response to What is LAS?

  1. Nice article but two things are not entirely accurate.

    1) The reduction in file size via conversion from ASCII to LAS is over-emphasized. It is the binary nature of LAS that makes it much faster at reading and writing LIDAR because conversion from and to a textual format is slow. Moreover, it is possible to seek: reading point number 1 million in an ASCII file, for example, requires reading the preceding 999,999 points as well. LAS avoids that. The data is not compressed, but rewritten into more structured binary records that may lower but may also increase the file size (for actual compression of LAS files there is the open source LASzip compressor).

    2) The scan angle does not indicate that the returning laser pulse has reflected off multiple surfaces before returning. It is simply the angle at which the laser pulse was sent out (i.e. it is a function of the rotating mirror). A scan angle of 0 usually means that the laser pulse was shooting straight down from the plane. But this is not necessarily the case: the scanner may be mounted to the plane at a slight angle.

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