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Thermography

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Photographic Techniques Index

Kite Aerial Thermography

 

AVI still

Thermal image of Cade taken at night near Armadale Stadium.

September 2011

Although thermal imaging cameras are coming down in price, they are still relatively expensive for use by amateurs. However, an individual thermopile can be used in conjunction with a scanner (2).

Unless strategic restrictions or market pricing policies are placed on the sale of the latest generation of thermal imagers, small, cheap 640 x 480 pixel imagers should be on the market well within the next five years. These smaller imagers will be more amenable to physical stabilisation techniques on KAP rigs and UAVs than those currently available to the general public.

A cheap low resolution thermal imager has now been produced (Spring 2014), the FLIR ONE iPhone infrared camera.

Details of our thermal cameras are in the Kite Aerial Thermography section.

JPG

A glowing Cade walking down a street in Armadale. Our first thermal IR image.

 2 September 2011

AVI still

Note the engine heat reflecting from the road and the differential cooling of the roof of the lower parked car.

 

Examples of colour mapping

Photoshop: Red, yellow, blue, three colour map. (image > adjust > gradient map)

GIMP (free): Romanian flag smooth color map.

(Thanks Heidi for the technique)

Unlike temperature-calibrated, colour thermal cameras, the colour range chosen for archaeological images should maximise the delineation of the features under investigation. Specific features can be also selectively coloured. However, in most instances, grayscale images should be fine.

Here is an example using a conventional thermal IR camera suspended from a balloon.

Thermal imaging cameras have been flown over archaeological sites by Ulrich Kiesow (using a microlight, www.archaeoflug.de) and others. We would like to thank Uli for his help and advice.

Inverted still image from the first thermal video of Villa Rustica, Kleinsteinhausen, Germany.

archaeoflug.de 2006

archaeoflug.de

Another excellent example, with the visible spectrum image on the left and the equivalent thermal image on the right.

Uli's work illustrates that thermal crop marks are most clear towards then end of a warm day in conditions of low humidity, which permits maximum differential transpiration. From the standpoint of kite aerial photography, the requirement of a reasonable wind could make conditions less than optimal, especially the strength of wind  required to lift our heavy thermal camera. An initial aerial study is being conducted by West Lothian Archaeology in conjunction with Dave Cowley of the RCAHMS on a Roman site in Falkirk. Visible, near and thermal IR aerial photographs will be taken over a period of time.

 

West Lothian Archaeology Group members have also been participating in a systematic thermal imaging study of experimental sites on a farm in Gloucestershire.

DART Project: Thermal Imaging.

 

A simple, visible spectrum, indirect thermal approach is to look at the differential melting of snow or frost.

Gormyre Hill (Inverted image).  KAP February 2009

 

 

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