Copenhagen, Monday, April 11, 2011

Thermal image Denmark

Thermal True Ortho overlain a ”normal” orthophoto covering
a part of central Odense City. The color scale in the thermal
ortho varies from blue=cold – red=hot.

Saving energy is of benefit for the environment as well as for the economy and one of the key factors is to reduce heat-loss from buildings. A thermal survey from aircraft is a quick and cost-effective method to make an overall classification of the heat-loss from buildings in cities, municipalities etc.

Blom introduced thermal mapping from aircraft last winter doing projects for three municipalities in Denmark.  Blom Germany did the flight-operational and pre-processing part and Blom Denmark did the following data processing resulting in an orthophoto showing the temperature variations in the building roofs (colour coded) and a table for all of the buildings – prepared for GIS-analysis – including the following temperature statistics based upon the observations: Average, Minimum, Maximum and Std. deviation.
The three projects in Denmark included:
Inner city of Odense, approx. 10sqkm, GSD 40cm
Municipality of Frederiksberg, approx. 10sqkm, GSD 50cm
and Municipality of Lyngby-Taarbaek, approx. 40 sqkm, GSD 50cm
Odense and Lyngby-Taarbaek have web-exposed the results.
The link to Odense is:
And the link to Lyngby-Taarbaek is:
For the project in Odense the thermal image data were processed to a true orthophoto , making use of a highly detailed 3D model covering the project area. All True Orthophotos were processed using  in-House developed software.
It’s important to emphasize that airborne thermal mapping is not an exact science resulting in high precision results. Using thermal sensor we measure an overnight snapshot of the Thermal Infrared Radiation (TIR) that emits from the objects (the building roofs).
This emitted energy can be converted to a temperature scale but there are some elements of uncertainty to be aware of since the TIR is influenced by the building material and microclimatic aspects like wind, moisture etc.  Besides this the building construction (e.g. ventilated roofs) and special events in the household during the moment of survey will of course influence the results.
Being aware of these reservations thermal airborne mapping is a very useful screening tool to identify areas/buildings where it seems probable that there is a high heat loss compared with the surroundings.
We expect that Thermal mapping will be improved during the coming year(s) due to better technology (further sensor development) and better methods/algorithms for data processing and interpretation using more data sources to validate the results.

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