I have been trying to calculate the volume of a small surface area. However, I am somewhat concerned about the differences I have encountered when using a TIN vs raster surface as the surface input. With the TIN I got a volume of 40000m cubed, with the raster (.asc) I got 50000m cubed. I know there will be differences in the result due to how each surface is constructed, but 20%? I find that a little disconcerting.
I don't know if this makes much difference but the TIN is derived from the raster in question using the raster to TIN tool. I did set the z tolerance (in the raster to TIN tool) to 0.01 so I assumed the surfaces would more or less the same.
So, does anyone know why there is such a big difference in the results? And which result do you think is more reliable?
Thanks