Three-dimensional longwave infrared synthetic image generation incorporating angular emissivity effects using ray-tracing techniques
Abstract
A technique for longwave infrared (LWIR) synthetic image generation (510) is shown
which yields improved radiomeiric accuracy in the 8-14 .tm bandpass. This process uses a
modified LOWTRAN 6 atmospheric transmission/upwelled radiance code and computer
graphics ray-tracing techniques. A scene is created by placing faceted objects into world
coordinates with rotation, translation, and scaling parameters. Each facet is assigned a
material index and temperature. The material index points to optical properties for that
material. The modified LOWTRAN 6 code incorporates sensor response function when
computing tables of the atmospheric transmission and upwelled and downwelled radiances.
A ray-traced image is then generated. A final synthetic LWIR scene is generated to
geometrically match an actual acquired scene so that radiometric comparisons can be made.