volume calculation of a pile of sand that rests on a round cone

Hello everyone,

I am new to working with pix4dmapper and am looking for help.

How can i calculate the volume of a pile of sand as accurately as possible when the pile rests on more than one plane (i send photos of that pile)? On one side, a pile of sand rests on a round cone. Is it possible with Pix4d Mapper to make the base surface from two or more planes that we would draw ourselves? What are the possible solutions?

Thanks in advance for any help

A pile of sand that causes problems: