Trispectral Colour Line Scanner System

The Trispectral Colour Line Scanner System has been developed by Axel Bochert of the Alfred Wegener Institute for Polar and Marine Research and Airborne Research Australia.

Depending on aircraft altitude and other operating parameters the instrument offers a resolution of better than 0.5m. This is achieved using high pixel resolution of 2048 pixels per line, and an acquisition frequency of 50 lines per second (stored directly onto a hard disk).

This scanner can operate in either of two modes - Visible (Red, Green and Blue) or Vegetation (Green, Red and Near-IR). Georeferencing with an absolute accuracy of a few metres is attainable in near real-time with automatic objective techniques developed in-house. Because of the accurate georeferencing, the compilation of time series is relatively simple. A further advantage is that combining adjacent swaths is simple, accurate and objective. The wide swath and accurate mosaicing means less wasted overlap imagery.

The scanner has been operated on several aircraft including

Dornier DO228

Cessna 404 Titan

Grob 109B Motorglider

Bölkow Blohm BO105 helicopter.

The Trispectral Colour Line Scanner is assembled as a compact unit, measuring just 110mm x 110mm x 300mm. The use of the ARA Grob 109B at an altitude of 1500’ and a speed of 50 knots results in a spatial resolution of just 0.4 metres on the ground with a swath of 1km. The pod mounted on the leading edge contains the downward pointing scanner and also a conventional video camera.

The scanner was first used as an imaging NDVI sensor by ARA. To calculate NDVI (Normalised Differential Vegetation Index) the red and near-IR band responses are used. Applications include the investigation of spatial and temporal variations of vegetation.

Photo courtesy of News Ltd. Using the scanner in the Cessna 404. This aircraft’s ground speed of just under 100 knots at an altitude of 4000’ results in a spatial resolution of 1 metre on the ground with a swath of 2.5 km.

A closeup of the scanner housing. A simple, clean layout allows easy access to the scanner if required.

In the ARA Cessna 404 the scanner is fitted into a pod underneath the fuselage. The scanner is shown in the center of the pod, which protects the instrument from dust and stones during takeoff and landing.

(Last update of this page: 2OCT99 by dgp)

	Using the scanner in the Cessna 404. This aircraft’s ground speed of just under 100 knots at an altitude of 4000’ results in a spatial resolution of 1 metre on the ground with a swath of 2.5 km.
A closeup of the scanner housing. A simple, clean layout allows easy access to the scanner if required.
	In the ARA Cessna 404 the scanner is fitted into a pod underneath the fuselage. The scanner is shown in the center of the pod, which protects the instrument from dust and stones during takeoff and landing.