A three-dimensional map of an environment with buildings is used to computationally predict locations and times of global navigation satellite system (GNSS) transmission quality. A global navigation satellite system (GNSS) receiver can reconcile received satellite transmissions with these predicted satellite transmissions. By comparing actual transmission quality with predicted transmission quality, a system can determine unmodeled obstructions, temporary obstructions, jamming, spoofing or other origins of interference with predicted transmission quality of a satellite in a GNSS.