Fire edge and boundary development using ArcGIS. The polygons (representing fires) from consecutive years were combined (grey column on left), then the overlaps that occurred were identified and the edge that was encountered during the most recent fire year was determined (second column, white). Finally, the interior lines were eliminated (third column, grey). This final mesh of outer fire perimeters became the Total Available Edge for fires in the next fire year. The process was repeated through the end of the fire years. Final products included Total Available Edge, Edge Encountered, Length Shared, and Length Breached by fire.