As a sweet foretaste to ILMF 2014, the creators of LAStools, LASzip, and PulseWaves are announcing “LASlayers” already on Valentine’s Day. The new functionality nicely complements their popular and widely-used LiDAR compressor making the compressed LAZ files editable for most practical purposes. LASlayers significantly reduce I/O load for writing modification to LAS or LAZ files, especially when batch-processing LiDAR tiles on many cores in parallel or when sending changes to LiDAR files across bandwidth-limited networks.
LASlayers store modifications and additional attributes to raw LAS or LAZ files in small LAY files avoiding to replicate data that has not changed.
Most point attributes (e.g. coordinates, intensities, scan angles, GPS times, etc.) are not modified when processing LiDAR. LASlayers avoids re-writing the unchanged portions of LAS or LAZ by storing only the actual differences layer by layer to a new “LAY” file. Changing the point classifications or deleting a few points, for example, can be done with LAY files that are just a tiny fraction of the size of a new LAS or LAZ file. Adding new attributes such as RGB colors or the height-above-ground with LASlayers means only this new information needs to be written.
This also provides simultaneous access to different versions of the data: a LiDAR server or a Web portal can store only a single copy of the raw LiDAR and apply LASlayers as needed on-the-fly, for example, to replace ellipsoidal with orthometric elevations or to add RGB colors.
Even users of other LiDAR processing software can readily take advantage of LASlayers with the new “laslayers.exe” tool that computes the difference between a raw and a modified LAS or LAZ file and expresses it as a LAY file (assuming the point order has not changed). A typical use case is the exchange of modifications to LiDAR files between remote locations such as a vendor in Australia or Canada and a data processing center in China or India. Instead of up- and downloading the entire modified LAS or LAZ files, only the much smaller LAY files need to be send back and forth.
A fully featured prototype of LASlayers is available (10 MB including data) together with three simple exercises that illustrate the concept and allow interested parties to test it already today on their own data