  Thermography allows for the remote measurement of surface temperatures and is
widely used for the identification of energy losses, damage detection or
quality control. However, thermal imaging is strongly material dependent and
therefore measured and real temperatures can differ significantly. The emission
coefficient resides between 0 and 1 and changes mainly with the electrical
conductivity of the surface. While non-conductive surfaces (stone, wood, glass
etc.) have a high emissivity of ca. 0.9, metallic surfaces reside around 0.2.
If e.g. an object with a temperature of 100$^\circ$C and E=0.9 gets recorded
via thermography, the recording shows a temperature of 90$^\circ$C. The same
conditions for a metallic surface on the other hand can result in a measured
temperature of only 20$^\circ$C, so room temperature.
  This article introduces a novel method how to approximate the electrical
conductivity of surfaces by the combination of geometric and spectral
information. A new thermographic panorama system called "ThermoHead" is used to
generate high-resolution and geometrically calibrated thermal images of the
surrounding. For the geometric information, a 3D point cloud from the very same
point of view will be recorded with an arbitrary commercial available
terrestrial 3D laser scanner. Since both data sets have been recorded
successively from the exact same point of view, the congruent combination
allows to transfer all geometric informations from the terrestrial 3D laser
scanner to the thermographic measurement. The radiometric intensity depends on
e.g. the angle of incidence of the thermographic measurement, which is now
known and can be used to narrow down the electrical conductivity of the
measured object.
