Steps to creating synthetic images of wildland fire Anthony Vodacek Center for Imaging Science Rochester Institute of Technology April 14, 2005

Flame Visualization – 3D Flame structure is not explicitly in the NCAR model nor is it in the fire propagation code – Does it matter if we create realistic flame structure and smoke? Needed for creating realistic synthetic images from model outputs for comparison to real images of a fire scene Needed for better visualization for the fire manager – How do we create realistic flame structure? Temperature data Real spectral data and blackbody spectral model Attenuation coefficient through flame 3D modeling of an emissive transparent object (a gas)

Albany NY pinebush thermocouple at surface of mineral soil Temperature data

Real Flame spectra and blackbody model Infrared Systems spectrometer continuously variable filter ASD spectrometer

Flame thickness and radiance Series of measurements on experimental fires at the Fire Science Lab

Flame thickness and radiance Relative radiance Flame thickness, feet Optically thin result, relative radiance was linear with temperature Attenuation coefficient is very small

Digital Imaging and Remote Sensing Image Generation Model (DIRSIG) A first principles ray tracing code that is spectral (visible to thermal) Facetized solid reflective surfaces Transmissive objects (tree leaves, gas plumes) Thermal history MODTRAN atmospheric model Sensor model

Voxels in DIRSIG A voxel is a 3D pixel Transmission through voxels (an attenuation coefficient) Voxel temperature (800 C)

Voxel emission -- for now 1x 2x 3x The voxel is an emitting source to the sensor We can do this now, see example New measurements at Missoula needed to determine spectral attenuation

Voxel emission – the future 1x 2x 3x The voxel as a secondary source New coding in DIRSIG is required. Ready by August?

Buoyancy output from the NCAR model In general, the higher the buoyancy, the relatively warmer the atmosphere Display buoyancy as grayscale Lower threshold, larger region, looks like smokeHigher threshold, smaller region, looks like flame Original data from Janice Coen, NCAR

grass fire DIRSIG scene 3D voxels 1073K blackbody ~10 m flames RGB (lines) Grass on ground No reflection from the fire to the ground

DIRSIG 2.2  m WASP image, Albany, NY Prescribed burn 1.35  m