FREQUENTLY ASKED QUESTIONS ABOUT THE ALASKA FIRE PERIMETERS DATABASE:

1. Why does the polygon attribute table not contain any useful information?

ANSWER: Because this is a regions coverage.  The pertinent attribute data
are stored in the region.firescars attribute table.  If you are using this
coverage in ArcView, you must click on the icon next to the coverage name
in the Load Theme dialog box and then choose firescars, not polygon.

2. Why do I get labels where there are no fire perimeters?

ANSWER: There are 307 records for which no mapped perimeter has been located.
These were included as a 10 meter buffer around the reported point of origin.
They are generally so small that you do not see them, but if you auto-label
the theme in ArcView, they will get labeled.  

3. How can I identify these tiny buffers around points?

ANSWER: By selecting on the Boundary attribute field.  There are three unique
values in the boundary field:

	Y -- region is a mapped fire perimeter.  In this instance, acres
		are acres in the digitized perimeter.
	N -- region is a 10 m buffer around a reported point of origin.
	     	In this instance, the acres are acres reported in the incident
		report.
	'' -- records with no value in the Boundary field are "doughnut holes."
		They should also have a sitename value of 0.

4. Why don't the fire perimeters line up with my other layers?

ANSWER: This coverage is stored in a geographic projection (double precision,
decimal degrees) referenced to the NAD27 datum.  For more information, refer 
to your software documentation on projections and coordinate systems.

5. What do you plan to do about the 300+ missing fire perimeters?
  
ANSWER: Filling in these perimeters is not a high priority.  They are all more
than 20 years old, and the quality of perimeter maps made at the time of the
fire is likely to be very poor.  As projects involving satellite imagery and
aerial photography come up, and as time permits, perimeters that are discernable
on the imagery will be noted and placed on a list for automation when staff
time is available.

6. How accurate are the fire perimeters?

ANSWER: That varies considerably.  Fires mapped within the past 15 to 20 years
are expected to be within +- 200 m of the actual location.  Fires mapped prior
to that may be up to +- 500 m.  The maximum allowable RMSE of map registration
during digitizing was 20 ground meters.  No formal assessment of positional
accuracy has been conducted.