# FAQ¶

• How do you pronounce PDAL?

The proper spelling of the project name is PDAL, in uppercase. It is pronounced to rhyme with “GDAL”.

• Why do I get the error “Couldn’t create … stage of type …”?

In almost all cases this error occurs because you’re trying to run a stage that is built as a plugin and the plugin (a shared library file or DLL) can’t be found by pdal. You can verify whether the plugin can be found by running “pdal –drivers”

If you’ve built pdal yourself, make sure you’ve requested to build the plugin in question (set BUILD_PLUGIN_PCL=ON, for example, in CMakeCache.txt).

If you’ve successfully built the plugin, a shared object called libpdal_plugin_<plugin type>_<plugin name>.<shared library extension> should have been created that’s installed in a location where pdal can find it. pdal will search the following paths for plugins: “.”, “./lib”, “../lib”, “./bin”, “../bin”.

You can also override the default search path by setting the environment variable PDAL_DRIVER_PATH to a list of directories that pdal should search for plugins.

• Why am I using 100GB of memory when trying to process a 10GB LAZ file?

If you’re performing an operation that is using standard mode, PDAL will read all points into memory at once. Compressed files, like LAZ, can decompress to much larger sizes before PDAL can process the data. Furthermore, some operations (notably DEM creation) can use large amounts of additional memory during processing before the output can be written.

• What is PDAL’s relationship to PCL?

PDAL is PCL’s data translation cousin. PDAL is focused on providing a declarative pipeline syntax for orchestrating translation operations. PDAL can also use PCL through the filters.pclblock mechanism. PDAL also supports reading and writing PCL PCD files using readers.pcd and writers.pcd.

PCL describes PDAL and PCL’s relationship.

• What is PDAL’s relationship to libLAS?

The idea behind libLAS was limited to LIDAR data and basic manipulation. libLAS was also trying to be partially compatible with LASlib and LAStools. PDAL, on the other hand, aims to be a ultimate library and a set of tools for manipulating and processing point clouds and is easily extensible by its users. Howard Butler talked more about this history in a GeoHipster interview in 2018.

• Are there any command line tools in PDAL similar to LAStools?

Yes. The pdal command provides a wide range of features which go far beyond basic LIDAR data processing. Additionally, PDAL is licensed under an open source license (this applies to the whole library and all command line tools).

No. The the command line interface was developed from scratch with focus on usability and readability. You will find that the pdal command has several well-organized subcommands such as info or translate (see Applications).