Title :
Forest Canopy Cover and Height From MISR in Topographically Complex Southwestern US Landscapes Assessed With High Quality Reference Data
Author :
Chopping, Mark ; North, Malcolm ; Chen, Jiquan ; Schaaf, Crystal B. ; Blair, J. Bryan ; Martonchik, John V. ; Bull, Michael A.
Author_Institution :
Dept. of Earth & Environ. Studies, Montclair State Univ., Montclair, NJ, USA
Abstract :
This study addresses the retrieval of spatially contiguous canopy cover and height estimates in southwestern US forests via inversion of a geometric-optical (GO) model against surface bidirectional reflectance factor (BRF) estimates from the Multi-angle Imaging SpectroRadiometer (MISR). Model inversion can provide such maps if good estimates of the background bidirectional reflectance distribution function (BRDF) are avail- able. The study area is in the Sierra National Forest in the Sierra Nevada of California. Tree number density, mean crown radius, and fractional cover reference estimates were obtained via analysis of QuickBird 0.6 m spatial resolution panchromatic imagery using the CANopy Analysis with Panchromatic Imagery (CANAPI) algorithm, while RH50, RH75 and RH100 (50%, 75%, and 100% energy return) height data were obtained from the NASA Laser Vegetation Imaging Sensor (LVIS), a full waveform light detection and ranging (lidar) instrument. These canopy parameters were used to drive a modified version of the simple GO model (SGM), accurately reproducing patterns of MISR 672 nm band surface reflectance (mean RMSE = 0.011, mean R2 = 0.82, N = 1048). Cover and height maps were obtained through model inversion against MISR 672 nm reflectance estimates on a 250 m grid. The free parameters were tree number density and mean crown radius. RMSE values with respect to reference data for the cover and height retrievals were 0.05 and 6.65 m, respectively, with R2 of 0.54 and 0.49. MISR can thus provide maps of forest cover and height in areas of topographic variation although refinements are required to improve retrieval precision.
Keywords :
height measurement; optical radar; radiometry; remote sensing by laser beam; topography (Earth); vegetation mapping; CANAPI algorithm; California; Canopy Analysis with Panchromatic Imagery; LVIS; MISR; Multiangle Imaging Spectroradiometer; NASA Laser Vegetation Imaging Sensor; QuickBird panchromatic imagery; RH100 height data; RH50 height data; RH75 height data; Sierra National Forest; Sierra Nevada; background BRDF; bidirectional reflectance distribution function; bidirectional reflectance factor; forest canopy cover estimate retrieval; forest canopy height estimate retrieval; fractional cover reference estimates; full waveform lidar instrument; geometric-optical model inversion; high quality reference data; mean crown radius estimates; simple GO model; southwestern USA; surface BRF estimates; topographically complex landscapes; tree number density estimates; wavelength 672 nm; Data models; Land surface; Laser radar; NASA; Remote sensing; Surface topography; Vegetation; Biomass; canopy; forestry; lidar; modeling; multiangle; topography;
Journal_Title :
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of
DOI :
10.1109/JSTARS.2012.2184270