Intensity return image from 2011 LiDAR, Blue River Watershed

This dataset represents the Blue River Watershed survey area in Linn and Lane County, OR. Each intensity image depicts, at a 0.5 meter resolution, normalized intensity values of the LiDAR laser returns. Watershed Sciences, Inc. collected the LiDAR and created this data set for the USDA Forest Service and the US Environmental Protection Agency.

Variability in the magnitude of intensity values across similar targets is a function of receiver auto gain control, laser power setting, atmospherics (transmissivity and target range), and angle of incidence. (Gain is a laser system setting that amplifies or dampens a return signal, resulting in artificially high or low intensity values.) These components influence intensity at different rates and magnitudes, with auto gain comprising the majority of influence. Variability in each of these components is minimized mathematically to arrive at a normalized intensity value that approaches a true radiometric value for each discrete LiDAR return. WSI employs proprietary software to normalize intensity values, based on assessment of the components discussed above, to a reference gain value for each laser employed in a LiDAR survey.