Mark, et. al.,
Michael has led the way in exploring and developing methods for measuring the basal area of tree trunks. A lot of progress has been made.
Below is a formula I recently derived for measuring the frustum of a slanted elliptical cone. If the ellipses are changed to circles, we get the standard formula for the frustum of a cone. The derivation is available for any one who wants to see it. Note that this formula does not need the height of the complete cone, only the frustum. You can find other formulas for the frustum of an elliptical cone, but they usually include the cone's total height.
Bob
Robert T. Leverett
Co-founder and Executive Director
Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest