What an Elevation Profile Is
The elevation profile graphically represents the variation in elevation along a GPS track.
Reading the profile makes it possible to quickly identify ascents, descents, flat sections and changes in slope along the route. The distance on the horizontal axis also shows how long the different sections are, while the elevation change on the vertical axis highlights the extent of the ascents and descents.
The horizontal axis generally shows the traveled distance, while the vertical axis displays altitude.
Minimum Elevation, Maximum Elevation and Elevation Gain
The minimum elevation indicates the lowest point of the route, while the maximum elevation represents the highest point reached.
Total positive elevation gain corresponds to the sum of all climbs completed, while negative elevation gain represents the total sum of descents.
Why Real Elevation Gain May Differ
Elevations recorded by GPS may contain errors caused by altitude noise, poor vertical accuracy or random position oscillations.
These errors can artificially increase the calculated total elevation gain, generating unrealistic results.
Slope and Route Difficulty
Analyzing climbs and descents allows evaluation of the physical difficulty of a route.
Steep slopes and concentrated elevation gains over short distances generally require greater effort during outdoor activities.
Elevation Correction with DEMs
To improve the accuracy and stability of the elevation profile, GPS elevations can be replaced with data from Digital Elevation Models (DEMs). However, the quality of the result also depends on the elevation model used: resolution, accuracy, geographic coverage and dataset characteristics can affect the resulting elevations.
OkMap supports SRTM data and local elevation models in GeoTIFF and ASCII Grid formats. To understand the main DEM sources and how to choose the most suitable model for different situations, see the article SRTM, Copernicus and Other DEMs: Which One to Choose?.
This operation makes it possible to obtain more realistic elevation profiles, reducing GPS measurement noise.
Elevation Analysis with OkMap
OkMap allows you to display detailed elevation profiles, calculate elevation gains and analyze climbs and descents along GPX tracks.
The software also allows you to correct elevations using DEMs, compare different routes and obtain complete elevation statistics. The required SRTM data can be downloaded automatically, while locally available GeoTIFF and ASCII Grid files are automatically detected when the program starts.
When multiple elevation data sources are available, OkMap also allows you to manage their priority. This makes it possible, for example, to use a high-resolution local DEM in a specific area and SRTM in areas where local data is not available.
The elevation gain and loss calculation in OkMap is designed to limit the effects of GPS elevation errors and random elevation fluctuations. This makes ascent and descent statistics more reliable and more representative of the actual route.