How Compare the usefulness and accuracy of dead reckoning with gps?

Dead reckoning is a navigation method that relies on estimating one's current position based on a previously determined location, using speed, direction, and time, making it useful in environments where GPS signals are weak or unavailable. However, its accuracy can degrade over time due to factors like drift and cumulative errors. In contrast, GPS provides real-time location information with high accuracy under ideal conditions, but its effectiveness can be hindered by obstructions like tall buildings or dense foliage. Overall, while GPS is generally more accurate, dead reckoning remains valuable in certain scenariOS where GPS is unreliable.