When I record a track, it shows wrong amount. On the dashboard it shows 1700 m. When I save the track then it shows 950 m. A big difference and I already have SRTM. During the tour, I always have wrong values in the dashboard. Then I can turn it off immediately.
All values are wrong. Some more than others, and this comparison of differes for different routes and conditions. The right values are impossible to know for LocusMap. They can be obtained only from detailed analysis of topographic data.
The particular values for the particular route strongly depend on way of obtaining raw altitude data, way of real time data processing and way of data postprocessing.
The best choice, if available, are barometric data with automatic calibration, and next best the replacing ( not optimizing ) GPS altitude data by SRTM altitudes ( still has noise due 2D position noise, but much better than GPS altitude noise). BTW, do you optimize GPS data, or Replace GPS data in altitude manager in SRTM context ?
For more, the best is to study the manual
http://docs.locusmap.eu/doku.php?id=manual:user_guide:tools:altitude#pressure_sensorTo comment particularly used postprocessing at particular places, I admit I am not sure, this is best for Menion to answer.