Incorporation of a time-dependent thermodynamic model and a radiation propagation model into infrared three-dimensional synthetic image generation
Abstract
A model is presented for generation of synthetic images representing
what an airborne or satellite thermal infrared imaging sensor
would record. The scene and the atmosphere are modeled spectrally with
final bandwidth determined by integration over the spectral bandwidth of
the sensor (the model will function from 0.25 to 20 rim). The scene is
created using a computer-aided-design package to create objects, assign
attributes to facets, and assemble the scene. Object temperatures are
computed using a thermodynamic model incorporating 24-h worth of meteorological
history, as well as pixel specific solar load (i.e., self-shadowing
is fully supported). The radiance reaching the sensor is computed using
a ray tracer and atmospheric propagation models that vary with wavelength
and slant range. Objects can be modeled as specular or diffuse
with emissivities (reflectivities) dependent on look angle and wavelength.
The resulting images mimic the phenomenology commonly observed by
high-resolution thermal infrared sensors to a point where the model can
be used as a research tool to evaluate the limitations in our understanding
of the thermal infrared imaging process.