When wildfire acreage is reported, does anyone know if local terrain is taken into consideration, or is the reported acreage the area as viewed on a map? I ask because the two figures are different. A square unit of area on a 30° slope would appear to be .866 square units on a map, whereas a square unit of area on a map would actually be 1.155 units of area on the slope (assuming I've done the math correctly, which I think I have). I'm guessing it's just the area as viewed on a map, because figuring out the average terrain would be pretty difficult, though not impossible.
The same issue arises when land is bought and sold. The area used is the flat area from a plan. Slope is not considered because it would require at lot of data because the rate of change of topography and slopes is never uniform. Also the calculations to determine the true area can be convoluted if the change in topography is complex.