LiDAR Equipment
This is a technology which is unrealistic and unnecessary for the Discovery Programme to own. Surveys have to be commissioned and data purchased from specialist service providers. The Discovery Programme has been working with Fugro-BKS Ltd to examine the archaeological potential of the high definition Fli-map 400 sensor.
Before delivery of the data several stages of processing are required by the LiDAR provider to enable final surface models to be created efficiently. They included:
1. Transformation of data to WGS84 & Irish National Grid
2. Output of tiled ASCII DSM
3. Removal of vegetation, buildings and above surface features using a combination of intensity and video inspection
4. Output of tiled ASCII DTM
Both DSM and DTM ASCII datasets are tiled to enable successful surface models to be created as the size of the complete datasets are unmanageable. Surface models are created using ArcGIS 9.2 including 3D Analyst and Spatial Analyst extensions. Firstly TIN models were created from each tile ASCII xyz data set. These are subsequently rasterised to improve display performance and merged into a single seamless DTM and DSM. Hillshade analysis of the generated surface is then carried out to aid the identification and description of archaeological features.