如果 sensor_msgs/NavSatFix.msg 中的“高度”读数为负，该怎么办？

Question

What to interpret and how to process the data in general when the values (from gps sensor) for "altitude" field in ROS sensor_msgs/NavSatFix.msg is negative ?

Answer 1

Even at sea level, altitude may be negative: GPS uses a mathematic earth model to estimate the height in mean sea level. This model is usually a simplified EGM96 geoid. The local sea level might be some meter higher or lower.

Just be aware that this is not unusual. Depending what your app Should do, you can display any value < 0 as 0.