High resolution satellite imagery was captured over Phnom Penh International Airport in the required eTOD survey areas outlined in ICAO Annex 15, Area 2 (a, b and c). Imagery capture was done through the Airbus DS Geo Pleiades satellite, with technical specifications as follows: 50cm spatial resolution, panchromatic and multispectral spatial and spectral bands, on stereo new collect acquisition mode. Acquisition period was November to December of 2019, covering an area of around 175 sqkm.

Captured imagery was processed for sensor orientation adjustment, automated DSM generation and DTM editing. We produced the following terrain models: a 3m posting digital surface model (DSM) and a 5m posting digital terrain model (DTM) with additional break-lines added to DTM points.

50cm pan sharpened and mosaicked imagery data was also produced, primarily for obstacle data and feature mapping.

A ground control point (GCP) survey was carried out over October to December 2019 for the purpose of accurately georeferencing satellite imagery captured over Phnom Penh, as well as for DSM and DTM generation.

25 points in total were surveyed, comprising of 10 newly acquired GCP and 15 control points derived from the control survey network (JICA) used for total station surveying. Multiple receivers were used simultaneously where possible for closed loops.

2 SATLAB SNL-600 GNSS base/rovers and one SL 800 rover were deployed, and all GNSS processing and adjustment was done on the Trimble Business Center, compiling all data into a single project using one PACS (primary control station point) provided by CATS and Cambodian civil aviation authorities. Processed data was then assembled in a GIS Database.

A total station survey was performed for identifying possible obstacle features in the field, surveying for their position, elevation and attribute data. This potential obstacle data was later integrated with obstacle data extracted from acquired satellite imagery.

The Leica TS-09 Reflectorless Total Station was used, able to measure distances without a reflector prism for up to 1000m. Total stations were based in the survey control stations established during the airport control network survey.

Optical surveys of areas adjacent to the aerodrome were carried out to capture more detailed information of obstacle features such as antennae and building eaves, to supplement, improve and verify satellite imagery.

Optical survey points were linked to target photos within the GIS database, with additional digital photography providing a wider field of view of points. Each point was assigned a corresponding eTOD type code, separated into point, line and polygon obstacles according to its attributes.