The Science Behind the Study
A
yres Associates opted to use remote
sensing for several reasons. Although
satellite data was readily available, it
simply wasn’t the right source for a project
of this magnitude. Its 5- to 30-meter-pixel-
resolution was far too large to analyze the
single trees and small stands Menominee
Tribal Enterprises was interested in
researching. Instead, Ayres’ aerial mappers
reversed the process and created objects
from each pixel collected in the spring and
fall flights.
The team collected data at carefully timed
internals when specific tree species would
be more easily identified – for instance,
during peak fall colors for aspen and mid-
spring to capture pin cherries at their peak
bloom.
Near-infrared imagery
Imagery with analyzed data
They then used segmentation techniques
to examine each pixel in an image and
compare it to adjacent pixels similar in
spectral signature and group shapes.
“You create an object, and then you start
matching pieces to that object,” explained
Adam Derringer, project manager. “It’s an
extremely heavy process, when you start
thinking about how many pixels are in
that 21-mile area, but you bring all that
together and then start to look at the
shapes. That gave us our segmentation
to use in our supervised classification
routines to identify the species.”
Spring near-infrared imagery
The team’s use of 6-inch-pixel-resolution
data over something like LandSAT data
gave MTE far more detailed data – 40
times more data, in fact – than what
satellite data would’ve provided.
In the end, the estimated accuracy of their
analysis was more than 90% against the
control data.
Analysis tested against ground truth points
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