Trying to calculate the surface area of a 3D polygon

I have a set of points that create a 3D polygon, I am looking to calculate a specific area of interest using my script. However, the area of interest is calculated to be 2-3x larger than expected. Could anyone provide insight as to what the problem might be?

I have verified that the xml file is correct and being processed properly by the script.

[KSSV]

We don't know how your polygon is. The given code has some files, which are not provided. So we cannot check your code.