Imaging Resolution in Ground Sample Distance: Fact or Fiction

Does the Ground Sample Distance really define the spatial details of imagery and is it even the right measure of resolution? A panel of experts from satellite, airborne and UAS discuss the definition of Ground Sample Distance and how it is applied across different modalities. How is GSD calculated? What contributes to resolution and more importantly how is GSD tested to assure the spatial detail and resolution aligns to project requirements? Finally is there a better way to describe the true spatial detail and image content of remote sensed imagery?