Accuracy Assessment in Remote Sensing:

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Accuracy Assessment in Remote Sensing Methods
for Positional and Thematic Accuracy
Assessment, the Role of Reference Data Chris
Elvidge NOAA National Geophysical Data Center 325
Broadway, Boulder, Colorado 80305 USA Tel.
1-303-497-6121 Fax. [phone] Email
chris.elvidge_at_noaa.gov January 22, 2002
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Positional Accuracy ReferenceU.S. Federal
Geographic Data Committee (FGDC) Geospatial
Positioning Accuracy Standards Part 3 National
Standards for Spatial Data Accuracy
(NSSDA) FGDC-STD-007.3-1998 http//www.fgdc.gov/
standards/status/sub1_3.html
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Positional Accuracy The NSSDA uses
root-mean-square error (RMSE) to estimate
positional accuracy. RMSE is the square root of
the average of the set of squared differences
between dataset coordinate values and coordinate
values from an independent source of higher
accuracy for identical points. Accuracy is
reported in ground distances at the 95
confidence level. This means that 95 of the
check points had errors equal to or smaller than
the reported accuracy value. A minimum of 20
check points shall be tested, distributed to
reflect the geographic area of interest and the
distribution of error in the dataset. When 20
points are tested, the 95 confidence level
allows one point to fall outside the reported
accuracy value.
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Thematic Accuracy Reference "Assessing the
Accuracy of Remotely Sensed Data Principles an
Practices", Russell G. Congalton and Kass Green,
1999, Lewis Publishers. "The pupose of
quantitative accuracy assessment is the
identification and measurement of map errors.
Quantitative accuracy assessment involves the
comparison of a site on a map against reference
information for the same site. The reference data
is assumed to be correct. Because comparison of
every spatial point is impractical, sample
comparisons are used to estimate the accuracy of
maps."
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Thematic Accuracy Asessement Uses An Error
Matrix With Accuracies Reported as Percentages
From Congalton and Green, 1999.
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For the positional accuracy assessment of active
fires what types of reference points could be
used? Uniquely identifiable terrain
features? Emissions from fixed point sources,
such as gas flares? Fires observed
sumultaneously (or near simultaneously) in fine
resolution satellite imagery (ETM, SPOT, ASTER,
BIRD)? Field data?
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For the thematic accuracy assessment of active
fires what types of reference data could be
used? Emissions from fixed point sources, such
as gas flares? Fires observed sumultaneously (or
near simultaneously) in fine resolution
satellite imagery (ETM, SPOT, ASTER,
BIRD)? Could an accuracy assessment of
cumulative fire detections be performed using
the bunr scar increment derived from pairs of
high spatial resolution images (ETM, SPOT,
etc)? Field data?
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For the positional accuracy assessment of burn
scars what types of reference points could be
used? Uniquely identifiable terrain
features? Emissions from fixed point sources,
such as gas flares? Burn scars derived for the
same time period from fine resolution satellite
imagery (ETM, SPOT, ASTER, BIRD)? Field data?
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For the thematic accuracy assessment of burn
scars what types of reference data could be
used? Burn scars derived for the same time
period from fine resolution satellite imagery
(ETM, SPOT, ASTER, BIRD)? Field data?