Introduction to Digital Elevation Models (DEM)

Discover what Digital Elevation Models (DEMs) are, how they are used to correct GPS elevations, and why they are essential for the elevation analysis of GPX tracks.

Introduction

Digital Elevation Models are one of the most important technologies for geographic and elevation analysis. Thanks to DEMs, it is possible to obtain accurate terrain elevation information, improve GPS track analysis, and calculate more realistic elevation profiles and elevation gains.

Digital Elevation Models, also called DEMs (Digital Elevation Models), are numerical representations of terrain elevations.

They are used in cartography, GIS, outdoor navigation and GPS analysis to obtain accurate elevation information and generate realistic elevation profiles.

Prerequisites

Basic knowledge of GPS and digital cartography
Maps or GPX tracks to analyze
Software compatible with DEM data

Topics covered

What DEM models are
Using DEMs in GPS tracks
Correction of elevation data
Elevation profiles and terrain analysis
DEM and outdoor cartography

What DEMs are

A DEM is a grid of numerical data that describes the terrain elevation at specific geographic coordinates.

Figure 1. A Digital Elevation Model (DEM) represents the Earth's surface as a regular grid of cells. Each cell stores an elevation value, making it possible to reconstruct the terrain morphology and calculate elevation profiles, slopes, aspect, and other topographic analyses.

Each cell in the model contains an elevation value, allowing the terrain shape to be digitally reconstructed.

Why DEMs are important

Elevations recorded by GPS receivers are often less accurate than horizontal coordinates.

Using DEMs makes it possible to correct GPS elevations, improve elevation profiles and obtain more realistic elevation gain values.

DEM and GPX track analysis

Digital Elevation Models are used to analyze GPX tracks, calculate ascents and descents and generate detailed elevation profiles.

These data are particularly useful for trekking, mountain biking, mountaineering and outdoor planning. For planning your routes, you may also find the article How to Plan GPX Routes for Hiking helpful.

DEM resolution and accuracy

The quality of a DEM mainly depends on its spatial resolution, that is, the distance between grid cells.

High-resolution DEMs allow more detailed analysis, but require more storage space and processing power.

To use a DEM correctly, it is also important that the data be associated with the correct coordinate system, so as to avoid misalignments with maps and GPS tracks.

Types of DEM data

DEMs can be derived from satellite surveys, radar, aerial photogrammetry or LIDAR scans. Among the most widely used datasets are SRTM, Copernicus DEM, ASTER and local LIDAR data. The choice of the most suitable model depends on geographic coverage, resolution, data quality and the type of analysis to be performed. For a comparison of the main datasets and to understand which DEM to use in different situations, see the article SRTM, Copernicus and Other DEMs: Which One to Choose?.

Using DEMs with OkMap

OkMap uses DEM data not only to display terrain elevations, but also to improve the accuracy of elevation analyses. GPS elevations can be replaced or corrected using values from the Digital Elevation Model, making it possible to obtain more reliable elevation profiles and elevation gain statistics.

OkMap allows you to load and use DEM data to correct GPS elevations, calculate elevation profiles and obtain detailed route statistics.

The software also allows integration of DEMs with raster maps and GPX tracks, improving the accuracy and quality of outdoor analyses.

Practical tips

Use DEMs compatible with the geographic area of interest
Prefer high-resolution DEMs for detailed analysis
Always correct noisy GPS elevation data
Verify the coordinate system of DEM data

Common mistakes

Confusing DEMs with raster maps
Using DEMs with insufficient resolution
Ignoring elevation errors in GPS tracks
Using DEM data not aligned with the correct cartographic system

Video tutorial

Prepare a Hiking Track

Frequently Asked Questions

What is a DEM?

A DEM (Digital Elevation Model) is a numerical representation of terrain in which each cell contains an elevation value. It is used for elevation analysis, cartography, and GIS applications.

What is a Digital Elevation Model used for?

Digital Elevation Models make it possible to generate elevation profiles, calculate elevation gains, correct GPS elevations, and analyze terrain morphology.

What is the difference between a DEM and a raster map?

A raster map contains cartographic images, while a DEM contains numerical elevation values used to describe the shape of the terrain.

Why use a DEM with GPX tracks?

DEM data make it possible to correct GPS elevations and obtain more accurate elevation profiles and elevation gain statistics than those derived solely from GPS-recorded data.

Summary

Digital Elevation Models are a fundamental tool for improving the accuracy and quality of elevation analyses. Using DEMs makes it possible to obtain more realistic elevation profiles, accurate elevation gain values and a better interpretation of outdoor GPS tracks.

Want to apply these concepts with OkMap?

After reading the technical articles, you can continue learning with practical video tutorials or download OkMap Desktop and work directly with maps, GPX tracks and GPS data.

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