Can the DIRSIG software model a LIDAR/LADAR system?

Yes. The DIRSIG model is one of the most sophisticated active laser scene simulations available. Several other LIDAR scene simulation tools simply ray-trace a range to the scene and apply image processing techniques to introduce beam related effects (speckle, etc.). What is generally unique to the DIRSIG modeling approach is that it performs a propagation of the beam into and out (down and up or out and back) of the scene. Unlike the simplified range measurement approaches, this approach allows the DIRSIG model to introduce multiple-bounce and/or multiple-scattering effects. In complex scenes or applications (e.g. foliage penetration, dense urban canyons, etc.) the delayed returns of these multiple scattered photons can create false or ghost returns that can impact data utility.

The DIRSIG model is primarily a radiometry engine that creates a spatial x spatial x time cube of returned energy. This allows the model to be used to simulate a wide variety of detector systems including linear mode, full waveform digitizer, Gieger-mode avalanche photo detectors (GmAPD), etc. Documentation for parsing the LIDAR output is available so that custom back-end detector models can be implemented by the user. The DIRSIG model ships with a GmAPD post-processing tool that converts the photon arrival cube to range triggers and geo-locates them using the platform location, orientation and pointing ephemeris data that is also generated by the model.