The archived outline of the Empire Fire spans about 9.0 km from west to east and 10.0 km from south to north. CAL FIRE places the incident at 1 Mile South of Bridalveil Campground in Yosemite. The mapped boundary provides a second way to locate the event: it shows the extent around that reference location.
| Start listed by CAL FIRE | 1 August 2017 |
|---|---|
| County listing | Mariposa |
| Reported area in hectares | 3,276 ha (converted from acres) |
| Extent of the mapped outline | 9.0 × 10.0 km (west–east × south–north) |
| Containment entry in the archive | 9 January 2018 |
What the perimeter shows
The two spans differ by only 1.0 km. That does not make this a circular burn: the dimensions measure the outermost coordinates, leaving indentations and gaps invisible. Use the polygon itself, rather than its enclosing rectangle, to check whether a location intersects the footprint.
Two estimates of area
The incident report gives 8,094 acres; the interagency feature stores 8,577.5 GIS acres. The mapped value is 483.5 acres above the reported value (5.97%). This compares two published measurements, not two observation times. The difference cannot be read as fire growth.
A similar-sized fire for comparison
The Pilot Fire of 2016 is the closest match by reported acreage in this 100-case collection (8,110 acres). Its mapped spans are 8.7 by 7.1 km, west–east then south–north, versus 9.0 by 10.0 km here. The longer axes run in different directions. Matching on acreage would miss that contrast.
Sources and map method
- Empire Fire · CAL FIRE incident record
- NIFC interagency history · source perimeter (GeoJSON)
- Pilot Fire · comparison incident
- Comparison perimeter · interagency record
Spans use the geographic extremes of a generalized boundary, converted to kilometres at its middle latitude. They are approximate map dimensions, not distances travelled by flames. The GIS acreage is the source attribute, not an area recalculated from the simplified outline.