What can be used for ground control in the georegistration process?
The process of determining and using ground control points to be using in the georegistration can be done by two methods: If georegistered imagery exists for the area being flown this imagery can be used as the ground control. This is the preferred method as it has the best turn around time and correlate between different images of the same area. Ground control points could be identified and the locations recorded by means of a GPS before the image area is flown. These locations will need to be identified in the resulting imagery so make sure to pick highly identifiable areas that are naturally occurring (e.g. rock pile) or use a marking method that is large and visible enough to identify. Using a marking method that is environmentally friendly and not permanent is recommended. This helps reduce the time required to retrieve the ground control points after the imagery has been flown.
