A read-only property giving the current area-of-interest (AOI)

A McRegions object.  

object.Aoi

The Aoi Property syntax has these parts:

The image Aoi property is used to restrict many operations to only those pixels that are under or interior to the region feature(s) that make up this property. An AOI can consist of one or more region-defining features, rectangular (McRegions.SetBox), elliptical (McRegions.SetEllipse) or polygonal (McFeatures.SetFeaturePoints). If the Aoi object has a Count of zero (IsReset, see notes) then the entire image is assumed to be the AOI.

The McImage.Aoi always exists and it is a read-only property, so to change it you cannot just assign a new McRegions object. Instead you need to use appropriate feature setting methods or use the CopyFrom method to import an AOI from the AoiList.

If the Aoi is empty, then it is forces to be IsReset as well, because the mcofOneFeatureOnly OptionFlags is always set for Aoi-type McRegions.