VOLUME 73, NUMBER 2
PHOTOGRAMMETRIC ENGINEERING & REMOTE
SENSING
JOURNAL OF THE AMERICAN SOCIETY FOR PHOTOGRAMMETRY
AND REMOTE SENSING
This month’s cover image, a digital elevation model (DEM) covering part of
the Angelo Costal Range Reserve in California, is provided
by Qi Chen from the Center for the Assessment and Monitoring
of Forest Resources at UC, Berkeley. The DEM was
produced from airborne lidar data using a software called
Tiffs (Toolbox for LiDAR Data Filtering and Forest Studies).
The raw lidar data have a total size of 2 Gigabytes and the
pulse density is about 5 points per m2. The site covers an
area of 35 square kilometers.
In an hour, Tiffs accomplished these tasks: 1) filtering the
point clouds and separating ground returns and canopy
returns, 2) generating digital elevation model (DEM), digital
surface model (DSM), and canopy height model (CHM), 3)
isolating tree crowns and extracting individual tree height,
crown area, and trunk height. The output models (DEM,
DSM, and CHM) have a cell size of 2m by 2m. The software
was run without tuning individual parameters and the images
shown were produced without any manual editing
of the point cloud.
The lidar data was courtesy of NCALM at UC, Berkeley.
Concepts from Photogrammetric stereo pair elevation extraction
have been extended to utilize three or more imagery
collects and to provide geometric correction information for a
pushbroom sensor.
Research comparing the slope gradient values calculated
using a circular neighborhood with the results from the traditional
square neighborhood used in a focal operation on a
raster layer.
The formulas for estimating accuracy measures derived from a
fuzzy error matrix when stratified random sampling is implemented
to obtain the reference data.