The Illinois Canopy Height Model (CHM) is a high-resolution (1 meter) raster dataset that maps the tree height as a continuous surface for Illinois. Each pixel in the CHM represents the tree overstory height above the underlying ground topography. It is derived from processing multiple terabytes of color infrared imagery from 2014 and LIDAR data flown between 2006 and 2014. LIDAR is a remote sensing technology that enables accurate measurement of elevation for different ground surface types based on the light pulses reflected from the earth.

The Illinois Canopy Height Model (CHM) dataset supports numerous applications for urban planning, forest inventory and ecosystem analysis.

A Digital Surface Model (DSM) was created from first returns of the LIDAR point cloud data and bare earth elevations were removed from the DSM to derive an above ground surface model. Buildings and tree canopy were differentiated in the above ground surface model using color infrared imagery through an expert rule based classification system. Tree heights were interpolated using the highest LIDAR return within each 1 meter pixel that was classified as tree canopy to generate the Canopy Height Model (CHM). Morphological filtering was used to fill small data gaps and pits to improve the cartographic quality of the final product.

US Tree Map

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Technical Specifications
Resolution	1 meter
Height Unit	Feet
Minimum Mapping Unit	0.005 acre
Area	39,160 sq. miles