I am using both Pix4Dmapper and Pix4Dsurvey to capture the volume of an object. In mapper, it is my understanding that when drawing the polygon bounding the box, it is a 2D plane to which we can adjust how we want to handle ground surface elevation (max, min, average). The volume reported seems questionable. I import the Pix4Dmapper project into Pix4Dsurvey and proceed to delineate the polygon around the object and calculate the volume, but it reports a different volume than Pix4Dmapper.
My question is how does survey use the DTM based within the polygon. Is it the same as Pix4Dmapper or is survey able to account for the topography with the polygon when calculating volumes or are do they both employ the same methods and why would there be a such a difference.