Full-waveform ALS workshop - Exercise A - Waveform Analysis

The exercises were the best part of the workshop. I think, the work in small groups (eight people) was very beneficial.




First Exercise: Waveform Analysis from Thomas Melzer and Andreas Roncat

"In this exercise, full-waveform analysis is demonstrated with a sample data
set of the 2005 ight mission over the Schonbrunn area, Vienna. In the rst
section of the exercise, single waveforms will be analysed, the second part focuses
on the overall processing of this sample data set."



Second part. Work with OPALS.

Exercise A-2: Fullwave Analysis Using Opals from Thomas Melzer

"This exercise illustrates how to use OPALS to
- perform fullwave analysis on the output of a RIEGL LMSQ-560 scanner (SDF format)
- transform the resulting point cloud from the scanner system into project coordinates, e.g. UTM ("weak" georeferencing)."



I wolud like to give some information about OPALS:

"OPALS stands for Orientation and Processing of Airborne Laser Scanning data. It is a modular program system consisting of small, well defined components referred to as ’modules’. Each module is accessible in three different ways:

• as commandline executable from within a DOS/unix shell
• as Python module from within a Python shell
• as C++ class via DLL linkage

Modern ALS sensors provide a huge amount of data (several Mio. points per km²). Thus, efficient management of point cloud data is a precondition for sucessful processing of ALS projects. Within OPALS, the administration of point and line related geometries is based on the OPALS Data Manager (ODM). The ODM acts as a spatial cache and features:

• high performance spatial queries (nearest neighbour and range queries) using two different spatial indices (K-d-tree for points and R*-tree for all other objects)
• an extensible adminstration scheme for storing arbitrary attributes (additional infos like (eg. echo width, echo number, amplitude, classification, surface normal vector, etc.) on a per point basis." (source: OPALS_gettingStarted.pdf)

more here: http://www.ipf.tuwien.ac.at/opals/opals_docu/index.php

I think, in the future we will hear more about this excellent software research....