I'm struggling with different DEM data, because I don't know how to convert the height information in meters.
When I load ASTER and SRTM tifs in QGIS, it shows me the spectrum of the grayband (0 to max). All the time I thought I could just take this value and see it as the height of each Point in m. Later I compared the graybandvalues with the actual height of the objects and realised that it's terribly off (German Zugspitze 500m, Test Area Swellendam 600m, a mountain in Malaysia more than 2000m). I tried it with different SRTM and ASTER DEMs, but no one was correct.
I would be very happy, if someone had an idea, how to solve this problem.