Draw a slope line under a fixed gradient

With this command, Pythagoras calculates a slope line starting from an existing reference line that connects under a fixed gradient to either a specified elevation or to a terrain model (DTM).

If you want the slope to connect to an existing terrain model, read the article Slope with a fixed distance to an existing terrain model but choose the Fixed Slope command instead.

WORKFLOW

1. Select a polyline
   This is the reference line from which the slope will start (for example, an edge or axis).

2. Go to DTM > Slope > Fixed Slope...
   The Fixed Slope dialog window opens.

3. Choose where the slope should connect to:

   • DTM: Select an existing terrain model from the list. The slope line will end at the intersection with the terrain (see Slope with Fixed Distance to Existing Terrain Model).

   • Elevation: Enter a fixed Z-value (e.g. 1.000). The slope line will extend until it reaches this elevation.

4. Choose the side: left or right of the polyline (depending on its drawing direction).

5. Set the slope:

   • Upward: check the option and enter a percentage (e.g. 45%) to calculate an ascending slope.

   • Downward: check the option and enter a percentage (e.g. –45%) to calculate a descending slope.

   • You can enable one or both options at the same time.

6. Optional: click Line Attributes to set the style, color, thickness, and layer for the generated slope line.

7. Click Calculate.

RESULT

Pythagoras generates one or more slope lines (depending on your choices) that start from the selected polyline and connect under the specified gradient to either a fixed elevation plane or the terrain model.

Important notes

• Separate lines are generated for upward and downward slopes, depending on what you select.

• The slope is expressed in percentage (%) and not in degrees.

• The left/right direction is determined by the order of the points in the polyline.

If you want to display the slope or the slanted distance, draw an auxiliary line between the top and bottom of the slope lines and annotate this with the tools: Slope annotation (in %) and Slanted length annotation. This way the slope information is also made visually available in your drawing.