Geoscience Reference
In-Depth Information
Interpreter Organization
Photo Interpreters
PI #1 (500 pts + 75 pts
from PI #2 and 75 pts
from PI #3
PI #2 (500 pts + 75 pts
from PI #1 and 75 pts
from PI #3
PI #3 (500 pts + 75 pts from
PI #1 and 75 pts from PI
#2
PI supervisor
Random checking for consistency, checking 225 overlapped sites, sites with question
from three PIs
Project supervisor
Checking sites with question from PI supervisor, random checking of overall sites,
overall QA/QC
Project director
Procedure establishment, discussions on issues, random checking, overall QA/QC
Classroom photo
interpretation training
Independent and
supervised photo
interpretation for each
interpreter
Interpretation of 225
overlap points
Interpreters work
through overlap points
as a group to resolve
differences
No
Overlap
satisfactory?
Yes
Photo interpretation of
the 1500 random
sample points
MRLC region
4 classified
data
Accuracy analysis
Figure 7.3
Tr aining, photo interpretation (PI), and quality assurance and quality control (QA/QC) procedures.
matrix for MRLC Level I classes. The Level II classes were grouped into the following Level I
categories: (1) water, (2) urban or developed, (3) bare surface, (4) agriculture and other grasslands,
(5) forest (upland), and (6) wetland (woody or nonwoody). The overall accuracies for the Level I
and II classes were 66% and 44%, respectively.
Table 7.3 illustrates the confusion among low-intensity residential, high-intensity residential,
and commercial/transportation categories. Many factors may have contributed to the confusion;
however, we believe the complex classification scheme used was a dominant factor. For example,
the most ambiguous categories were the three urban classes, which were distinguished only by
percentage of vegetation. Technically, it was beyond the methods employed in this study to quantify
subpixel vegetation content. As a result, many high-intensity residential areas in the classified image
were assigned to low-intensity residential and commercial/transportation classes. This occurred
because high-intensity residential classes, which had a median percentage of vegetation, were easily
confused with lower-intensity and higher-intensity urban development.
Also, many problems were encountered with the interpretation of cropland and pasture/hay
since these classes had very similar spectral and spatial patterns that occurred within the same
agricultural areas. In addition, cropland was frequently converted to pasture/hay during the interval
of two acquisition dates, or vice versa. Confusion also existed within classes of evergreen forest