# AT Quality Report values

Hi All,

I'm wanting to know how a few of the values in the AT's Quality Report are calculated, as I can't replicate them. Specifically the "Average ground resolution" (first page) and "median resolution" (in Tie Point Resolution section)

These values often seem around 10% lower than they should be to me based on ground sample distance calculations for several projects.

I'm assuming that to calculate the median resolution a mean GSD is calculated based on the observations for each tie point, then the median is taken for the whole tie point cloud. Is this not the case? The programs we've written to parse the block XML and then compute this process are returning slightly higher values. Perhaps high outliers are being disregarded when the report is created?