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ALS Data Processing

Not all current LBI ArchPro case studies were covered with digital surface and digital terrain models (DSM/DTM). For those study areas with existing models, additional documentation has been created, while in case of those without existing models new ones were generated from available data, including appropriate documentation.

For an advanced DTM generation for archaeological interpretation we focused on the development and testing of a workflow for hierarchical robust interpolation. After completing the workflow development, the workflow was tested for several case study areas. The usability of different software packages was studied and unified reports and a detailed comparison have been prepared for four tested software packages.

Workflows already known from the DTM generation from ALS data are being used, adapted and extended for TLS data. In order to acquire usable test data the Stonehenge project area was scanned using the latest terrestrial laser scanners. Georeferencing and a first cleaning of the TLS data acquired at Stonehenge (automatic elimination of vegetation points, data homogenisation) took place and has progressed well.

The tasks of georeferencing and data fusion comprised mainly the complete reprocessing of ALS data obtained from the Norwegian partner NIKU, as well as the processing and analysis of the ALS data sets from St. Anna and Carnuntum, which have been completed. The processing of the Norwegian data was conducted for the monitoring of topographic landscape changes through time in the area of archaeological monuments at Mølen in Vestfold in collaboration with partner NIKU. 

The radiometric calibration of ALS data was investigated together with partner TU Vienna. For the calibration, the simultaneously acquired spectrometer observations were used and the entire ALS data set of Carnuntum was calibrated based on these observations. In the simultaneous ALS and AIS data acquisition from June 18th 2012, five test areas were chosen to compare the ALS-radiometry with the simultaneously acquired orthophotographs and hyper spectral data. For automated visualizations based on ALS data, the ALS visualization toolbox has been created. It consists of specific tools from the range of ArcGIS scripts, LasTools, Topography Tools and solutions developed in-house.

Semi-automatic data classification algorithms for ALS data were developed and tested for magnetic prospection data using multi-scale hierarchical data segmentation, object-oriented definition of semantic classes for data classification and an interactive classification workflow resulting in data sets devoid of unclassified areas. This approach has the potential to be expanded to 2D GPR depthslice data and possibly even 3D GPR volume data.

Riegl Laser Measurement Systems