1. 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. 1-303-497-6513 Email: chris.elvidge@noaa.govchris.elvidge@noaa.gov January 22, 2002

2. Positional Accuracy Reference:U.S. Federal Geographic Data Committee (FGDC) Geospatial Posiioning Accuracy Statndards Part 3: National Standards for Spatial Data Accuracy (NSSDA) FGDC-STD-007.3-1998 http://www.fgdc.gov/standards/status/sub1_3.html

3. 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.

4. 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."

5. Thematic Accuracy Asessement Uses An Error Matrix With Accuracies Reported as Percentages From Congalton and Green, 1999.

6. 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?

7. 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?

8. 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?

9. 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?