Pointcloud file format conversions

A tool to convert point cloud files in the LAS/LAZ formats to other custom formats. These formats are experimental and were developed for the "Executing ad-hoc queries on large geospatial data sets without acceleration structures" paper. Besides converting from LAS to LAZ and vice versa, the following new file formats are introduced by this tool:

• LAST ("LAS Transposed") is identical to the LAS format, but the memory layout is transposed so that all values of a single attribute are stored together in memory, as opposed to LAS which stores all attributes of a single point together in memory
• LAZT ("LAST but Zipped") is identical to LAST, but the whole file is compressed using the LZ4 compression algorithm
• LAZER ("LAZ for Efficient Reading"), a variant of LAZ that uses a different compression algorithm (LZ4). This format stores points in blocks of a fixed number of points, where each block has the same memory layout as the LAST file, preceeded by a block header. Within a block, all attributes use a separate compression context, the block header stores the offset from the start of the block to the start of the compressed attributes to enable faster attribute lookup
• LASER, which is like LAZER but without compression

Usage

Requires a recent Rust installation (>=1.51), or Docker. With Rust, simply run cargo run --release to get information about the usage. In its simplest form, converting from one format to another works like this:

cargo run --release -- LAST source_file.las target_file.last

For the compressed formats, there are also some additional flags available:

• -c X with X in [1;9] specifies the amount of compression. See the LZ4 specification for more details
• -b X specifies the block size X (i.e. the number of points per block) for the LASER and LAZER formats. A good default is 50_000, which is the same value that LAZ uses

This project is licensed under the MIT license.