Pix4Dmapper volume calculation from external base surface

I need to calculate the volume of a specific stockpile using an imported LandXML file as the reference base surface in PIX4Dmatic.

Current project setup:

  1. Dense Point Cloud generated.

  2. LandXML file imported (File > Import > Volume base surface).

Current issue: When I use the Volume measurement tool to draw a polygon around my specific area of interest, the software calculates the volume based on the triangulation of the polygon’s vertices. It ignores the underlying LandXML surface. Conversely, if I compute the volume directly on the imported LandXML layer, the software calculates the volume for the entire extent of the imported model, rather than just the specific region of interest I want to measure.

Questions:

  1. What is the correct workflow in PIX4Dmatic to restrict a volume calculation to a specific drawn boundary (polygon) while forcing the software to use the imported LandXML file as the bottom reference surface?

  2. Is there a built-in function to clip or bound the imported LandXML surface using a drawn polygon within PIX4Dmatic, or does the LandXML file strictly need to be pre-cropped to the area of interest in a third-party CAD/GIS software before importing?