# Dependencies

Author: | Howard Butler
Contact: | howard@hobu.co
Date: | 11/03/2015

PDAL explicitly stands on the shoulders of giants that have come before it. Specifically, PDAL depends on a number of libraries to do its work. Most are not required. For optional dependencies, PDAL utilizes a dynamically-linked plugin architecture that loads them at runtime.

## Required Dependencies

### GDAL

PDAL uses GDAL for spatial reference system description manipulation, and image reading supporting for the NITF driver, and writers.oci support. In conjunction with GeoTIFF, GDAL is used to convert GeoTIFF keys and OGC WKT SRS description strings into formats required by specific drivers. While PDAL can be built without GDAL support, if you want SRS manipulation and description ability, you must have GDAL (and GeoTIFF) linked in at compile time.

Obtain GDAL via whatever method is convenient. Linux platforms such as Debian have DebianGIS, Mac OS X has the KyngChaos software frameworks, and Windows has the OSGeo4W platform.

- GDAL 1.9+ is required.

Warning

If you are using OSGeo4W as your provider of GDAL, you must make sure to use the GDAL 1.9 package.

### GeoTIFF

PDAL uses GeoTIFF in conjunction with GDAL for GeoTIFF key support in the LAS driver. Obtain GeoTIFF from the same place you got GDAL.

- libgeotiff 1.3.0+ is required

Note

GDAL surreptitiously embeds a copy of GeoTIFF in its library build but there is no way for you to know this. In addition to embedding libgeotiff, it also strips away the library symbols that PDAL needs, meaning that PDAL can’t simply link against GDAL. If you are building both of these libraries yourself, make sure you build GDAL using the “External libgeotiff” option, which will prevent the insanity that can ensue on some platforms. OSGeo4W users, including those using that platform to link and build PDAL themselves, do not need to worry about this issue.

### Proj.4

Proj.4 is the projection engine that PDAL uses for the filters.reprojection filter. It is used by GDAL.

Note

Proj.4 4.9.0+ is required if you need vertical datum transformation support. Otherwise, older versions should be sufficient.

## Optional Dependencies

### libxml2

libxml2 is used to serialize PDAL dimension descriptions into XML for the database drivers such as writers.oci, readers.sqlite, or readers.pgpointcloud

Note

libxml 2.7.0+ is required. Older versions may also work but are untested.

### OCI

Obtain the Oracle Instant Client and install in a location on your system. Be sure to install both the “Basic” and the “SDK” modules. Set your `ORACLE_HOME` environment variable system- or user-wide to point to this location so the CMake configuration can find your install. OCI is used by both writers.oci and readers.oci for Oracle Point Cloud read/write support.

Warning

OCI’s libraries are inconsistently named. You may need to create symbolic links for some library names in order for the CMake to find them:

    cd $ORACLE_HOME
    ln -s libocci.so.11.1 libocci.so
    ln -s libclntsh.so.11.1 libclntsh.so
    ln -s libociei.so.11.1 libociei.so

- OCI 10g+ is required.

Note

MSVC should only require the oci.lib and oci.dll library and dlls.

### Hexer

Hexer is a library with a simple CMake-based build system that provides simple hexagon gridding of large point sets for density surface generation and boundary approximation. It can be obtained via github.com at https://github.com/hobu/hexer It is used by filters.hexbin to output density surfaces and boundary approximations.

### Nitro

Nitro is a library that provides NITF support for PDAL to write LAS-in-NITF files for writers.nitf. PDAL can only use a fork of Nitro located at http://github.com/hobu/nitro instead of the mainline tree for two reasons:

1. The fork contains a simple CMake-based build system
2. The fork properly dynamically links on Windows to maintain LGPL compliance.

It is expected that the fork will go away once these items are incorporated into the main source tree.

### LASzip

LASzip is a library with a simple CMake-based build system that provides periodic compression of ASPRS LAS data. It is used by the writers.las and readers.las to provide compressed LAS support.

### laz-perf

In addition to LASzip, you can use the alternative laz-perf library. laz-perf provides slightly faster decompression capability for typical LAS files. It is also used as a compression type for writers.oci and writers.sqlite

### PCL

The Point Cloud Library (PCL) is used by the pcl, writers.pcd, readers.pcd, and filters.pclblock to provide support for various PCL-related operations.

PCL must be 1.7.2+. We do our best to keep this up-to-date with PCL master.

Note

Homebrew-based OSX builds use PCL 1.7.2, but you may need to switch off VTK support depending on the configuration.