Geophysical Mapping: Method Details
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Method Name: Airborne infrared thermography
Method Type:   Thermic Methods
Assigned Problems:
+ Regional Mapping Regional Mapping
+ Temperature Groundwater
0 Aquifer pollution Groundwater
   '+' = Technique applicable; '0' = Application possible/limited use
Principle:   Determination of ground temperature using airborne infrared surface temperature measurements (thermal/ infrared radiation; remote sensing).
Keywords:   Airborne thermal imaging; airborne geophysics; infrared measurements; thermal and infrared radiation; temperature distribution
  • Existence of thermal contrast
  • Weather / climate conditions: images may be difficult to interpret if recorded over snow-covered areas, wet ground, frost or during high wind.
  • Clouds influence measurements significantly.
  • Images may be distorted due to aircraft roll.
Resolution:   Instrument depending; in general, increasing thermal resolution decreases the spatial resolution, and vice versa.

Depth of investigation: Surface heat distribution, but also covered heat sources (e.g., smouldering) may be identifiable.

Expected Results:  
  • Measured parameter: Infrared thermography measures the intensity of the emitted electromagnetic radiation of a body
  • Data analysis: The measured signal may then be converted to temperature (emission coefficient / emissivity must be known)
  • Interpretation: Infrared thermography: qualitative interpretation of relative thermal anomalies assuming that the measured signal (intensity of electromagnetic radiation) is correlated to the true temperature.
Combination with other Methods:  
  • Required additional information: Weather conditions, camera information (valuable wavelength, etc.), camera setup, flight parameter (for processing / interpretation)
  • Related add-on information: Ground infrared thermography and ground temperature probing
  • Independent additional information: Investigations on site / ground depending on field of applications
Operating Expense:  
  • Crew size: flight crew (normally 2 persons)
  • Acquisition speed: several measurements per hour
  • Processing: 1 - 2 days per measuring day
  • Equipment rental costs: high
Parameters to specify:  
  • Line spacing; survey area is divided up into parallel tracks. Tracks should partially overlap to allow for wind gusts, aircraft roll or positional errors
  • Line direction
  • Flight altitude or height above ground; flight altitude: depending on target size from several tens to several hundreds of m
  • Tolerances for altitude and positional deviations
  • Weather conditions
QC Documents:  
  • Field notes (e.g., all activities, effective time schedule, present personnel)
  • Map/ images (or profiles) of temperature distribution
  • Interpretation
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