At Engineering Surveys we look at each project on a stand alone basis and match the available technology together with the client specification and relevant information. Where UAV photogrammetry provides an advantage in terms of cost/accuracy or program we shall consider this approach.
A typical high resolution data collection project will typically come down to Aerial (or Terrestrial) photogrammetry versus High Definition laser scanning. Both technologies can provide a high resolution point cloud suitable for modelling. The decision on which to use is based on:
- Access, can the scanner cover the entire area.
- Flying permission. In order to fly the photography it is necessary to keep at least 25m away from buildings and have full control of the area (within 50m) of the flight path.
- Visibility. Do the “shadow areas” present problems.
- Time and Cost
- Accuracy required.
ESL have successfully applied for flight permits from the CAD in Hong Kong on a number of projects. Most recently, In October 2018 we completed the Green Island Heritage Site Survey and have just received our Flight permit for the Lamma Power Station Project due to commence in December 2018.