Overlay elevation, grade, heart rate, and GPS route data onto trail running footage.
Trail running FIT files contain barometric altitude, GPS position, heart rate, pace, cadence, and sometimes temperature. MetricsOverlay reads all of it.
The grade overlay shows incline/decline as a percentage in real time. Positive values on climbs, negative on descents. Pairs well with heart rate to show effort vs terrain.
Vertical gain shows cumulative elevation gained. Useful for ultra and mountain content where total vert matters.
GPS map works well for trails since they have distinctive shapes. Follow mode zooms in and tracks your position through switchbacks.