012] How to Calculate Elevation Gain and Slope for Line Features in Global Mapper

Calculate detailed elevation gain, loss, and slope statistics along any line feature to analyze routes.

This tutorial demonstrates how to use Global Mapper’s Analysis tools to calculate terrain statistics for road or path features. You will learn how to interpret cumulative elevation changes, 3D lengths, and how to optimize the Path Profile visualization for technical reporting.

Preparing the Terrain and Road Data

Today, we will learn how to extract terrain information using Line features.

To follow along, please open the data file we used in the previous session.

Global Mapper screen showing the terrain, boundary, and road line from the previous session
img 1 : Global Mapper screen showing the terrain, boundary, and road line from the previous session

1. Extracting Terrain Information for a Line

The process is identical to the one we used for polygons. We will use the same tool to analyze the terrain along our "Road" feature.

  1. Select the Road line using the Digitizer Tool.

  2. Right-click and select Analysis/Measurement -> Calculate Elevation/Slope Stats for Selected Feature(s)....

Right-click menu on the line feature selecting Calculate Elevation/Slope Stats
img 2 : Right-click menu on the line feature selecting Calculate Elevation/Slope Stats

  1. A dialog will appear asking if you'd like to create new point features at the minimum and maximum elevations. Choose your preference (Yes to add points, No to just calculate).

Point creation confirmation dialog for min/max elevation points
img 3 : Point creation confirmation dialog for min/max elevation points

If you select "Yes," points will be generated on your map showing the exact locations of the highest and lowest elevations along that line.

Main screen showing the road with blue and yellow triangle markers at min/max spots
img 4 : Main screen showing the road with blue and yellow triangle markers at min/max spots

Analyzing Elevation and Slope Statistics

2. Understanding Line-Specific Statistics

The Feature Information window will now display the results. While similar to the polygon results, there are several key items specific to line features.

Feature Information window showing comprehensive statistics for the road line
img 5 : Feature Information window showing comprehensive statistics for the road line

Key Statistics Explained for Lines:

  1. MAX_UP_SLOPE_DEG/PCT: The steepest incline (uphill) encountered along the path.

  2. MAX_DOWN_SLOPE_DEG/PCT: The steepest decline (downhill) encountered along the path.

  3. ELEV_GAIN_M/FT: The total cumulative elevation gain (sum of all uphill segments).

  4. ELEV_LOSS_M/FT: The total cumulative elevation loss (sum of all downhill segments).

  5. LENGTH_3D: The actual 3D distance of the line, taking the terrain's rises and falls into account.

Note on Direction:

In Global Mapper, lines have a direction. The Start point is marked in Green, and the End point is marked in Red when selected. "Up" and "Down" are relative to moving from the green point to the red point.

In this example, the ELEV_GAIN is 26.91m and the ELEV_LOSS is 16.94m. This means that while traveling from the start to the end, you climbed a total of 26.91m and descended 16.94m. Consequently, the end point is approximately 10m higher than the start.

Visualizing Terrain Profiles

3. Review: Using Path Profile

Let's visualize this data using the Path Profile tool we covered previously.

  1. With the line selected, right-click and select Analysis/Measurement -> PATH PROFILE - Generate Path Profile Along Line(s)....

Right-click menu selecting Path Profile
img 6 : Right-click menu selecting Path Profile

A cross-section of the terrain along the line will appear. The yellow dots at the bottom represent the vertices (corners) of the line.

Initial Path Profile window showing the terrain cross-section
img 7 : Initial Path Profile window showing the terrain cross-section

The default view might show a lot of empty space below the terrain. Let's adjust the settings to focus on the relevant elevation.

  1. Go to Path Setup -> Path Profile Settings....

Path Profile menu selecting Settings
img 8 : Path Profile menu selecting Settings

  1. In the General Settings tab:

    • Elevation Range: Check Clamp Bottom Displayed Elevation to and enter 75 (meters).

    • Guidelines: Check Draw Reference Line at and enter 90 (meters).

    • Click OK.

Path Profile Settings dialog with custom elevation and reference line values
img 9 : Path Profile Settings dialog with custom elevation and reference line values

Now, the unnecessary bottom space is removed, and a clear reference line is added at 90m.

Final Path Profile view with optimized elevation range and reference line
img 10 : Final Path Profile view with optimized elevation range and reference line

This analysis is incredibly useful for evaluating hiking trails, bicycle paths, or planned road routes. If you have multiple potential paths from point A to point B, comparing the total elevation gain and loss will tell you which route is the easiest or most challenging.

Engineers, GIS analysts, and planners frequently use these statistics to evaluate road gradients, trail difficulty, drainage paths, and construction feasibility.

That’s all for today!

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