Tutorial #A05 : DEM Generation and Elevation Profile

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DEM Generation and Elevation Profile

 

Welcome to the 3DF Zephyr tutorial series.
In the following tutorial, we will learn how to create DSMs (Digital Surface Models), DTMs (Digital Terrain Models) and Elevation Profiles.
This tutorial cannot be completed with 3DF Zephyr Free or Lite versions!

 

 

Summary

 

 

 

 

 

 
 

  • Introduction

In 3DF Zephyr, we can create DSMs and DTMs via the Orthophoto Generation Wizard and view them directly from the DEM Viewer Utility, which can also be used to:
 

  • load DSM / DTM and multi-tiled DSM/DTM files (even those not related to the project you are working on);
  • load Contour lines on DSM / DTM if they have been previously generated in 3DF Zephyr;
  • export DSM / DTM as an image (available formats: .png, .jpg, .bmp) by clicking on File > Export color image;
  • calculate measurements, area and generate Elevation Profiles.

    •  

DSM/DTM files and Orthophotos are automatically loaded together if located in the same directory or project. Here is an example of contour lines, DEM, and orthophoto mixed together inside the DEM viewer:

 

The DEM viewer options are organized as follows:

– The File menu includes the:

  • Open from files option: it loads DSM and DTM files in .tiff format (even those related to a previous project).
  • Open from workspace option loads both DEM files and orthophotos previously saved in the current project.
  • Export color images option: allows exporting DEM files to one of the following image formats: .png, .jpg, .bmp.

 

– The View menu allows to select:

  • The Band option displays the DSM or the DTM (if both have been created).
  • The Rendering Orthophoto option: Enables/disables the orthophoto view under the DEM.
  • The Color Map option allows to change the Color Type, invert colors, and set Color Map levels between 4 and 256. Clicking on the color name will allow to select the desired band (Default Color: Jet)
  • The Show Polylines option enables the polylines view (sections, contour lines, or drawing elements) if they have been created.

 

– The Tools menu allows enabling:

  • The Enable distance tool: activates the cursor for placing points on the DEM and taking measurements.
  • The Enable area tool activates the cursor to place at least 3 points on the DEM and calculating the area.
  • The Elevation profile tool activates the cursor to place points on the DEM and creating the Elevation profile.

 

– The Color bar on the left side of the DEM viewer allows to set the elevation range thanks to the minimum and maximum elevation thresholds.
 

As an example for this tutorial, it can use the public dataset linked below:

download eptDataset Download – Mining site (642 MB)

 

 
 

  • Step 1 – DTM and DSM generation

Return to summary
 

This step matches the “Orthophoto Generation Tutorial” as it require to generate an Orthophoto before creating any DSM / DTM. Remember to flag the Generate DTM checkbox in the Step 3 – Export settings page during the orthophoto creation wizard.

 

At the end of the orthophoto generation wizard process or upon creating a new project, the recently generated orthophoto will be listed in the Project tab under the dedicated Orthophoto section. The DEM viewer will automatically activate upon completion of the computation, displaying the newly created DEM in the 3DF Zephyr interface.

 
 

  • Step 2 – Open the DEM Viewer and load/export the files

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The DEM viewer can be opened in 3DF Zephyr menu bar: Utilities (1) > Images (2) > DEM viewer Utility (3).


 

In The File menu, you can use the options to load the files in the viewer:

    – Open from files option: it loads DTM and DSM files in .tiff format. This command is useful for viewing the DEM files in the viewer, not necessarily related to the project you are working on. Selecting the DSM will load the corresponding DTM, and it will possible to change their display in the menu View > Band.

     
    – Open from workspace option loads both DEM files and orthophotos previously saved in the current project.

     
    – Export color images option: it allows exporting DEM files to one of the following image formats: .png, .jpg, .bmp.

 

 
 

  • Step 3 – Taking Measurements in the DEM viewer

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Distance (1) measurement tools can be activated from the Tools menu or by clicking directly on the respective buttons in the DEM interface. Using the cursor, place two points on the DEM to create a Distance (2), and click again on the “Enable distance tool” (1) button to exit the tool.


 

The tool for measuring Area (3) works in a similar way but requires placing at least three points on the DEM to calculate the Area (4). Click on the “Enable area tool” (3) button to exit the tool.

 

 
 

  • Step 4 – Elevation Profile Creation

Return to summary
 

The DEM viewer allows creating one or more Elevation profiles that, as Drawing elements, can be exported to both .pdf and .dxf formats.
To draw an Elevation profile, click the “Tools” (1) menu in the DEM viewer and select the “Enable Elevation Profile tool” (2) option. Alternatively, click the corresponding icon button and pick at least two points (3) to draw a profile on your DSM / DTM. You will notice that each vertex will be identified by a White Point (see image below).


 

Once all the profile vertices have been placed, click the “Enable Elevation Profile tool” (4) again or double-click to add the “Last vertex” (4a). The Generate Elevation Profile (5) setup page will automatically pop up.

 

You will notice that both the Quota and Progressive entries are already listed in the chart, and you can:

    – define the Step size in meters (distance between each quota/progressive value) or the Step count, by flagging the check box;

    – Add Latitude and Longitude Configurations.

    – Add Setup/Delete Setup/Edit/Move up/Move down your Quota, Progressive, Latitude and Longitude entries by clicking the related button.

 

Click “Next” (6) to select the Profile (7) you want to generate from the drop-down menu on the Preview (8) page, and the Elevation profile will be automatically created.


 

You can click the Export (9) button to select the desired Format (.pdf, .dxf) and the Page size and Resolution of the .pdf layout. Click “Finish” (10) to exit the DEM Viewer.
 

*TIP* - Are there any alternatives for creating an Elevation profile?

    – you can generate an Elevation profile from a Polyline you have already drawn by clicking “Tools” > “Sections and Contour lines” > “Elevation profile from drawing elements” and selecting the desired Drawing element using the “Add” button on the Setup page.

     

    – you can generate an Elevation profile from a Group of control points you have previously placed on the 3D model by clicking “Tools” > “Lines extraction” > “Make polyline from control points” and continuing the above workflow to generate an Elevation profile from a Polyline.

 
 

  • Final notes

Return to summary
 

Below; you can find a final summary video of this tutorial:

In the Quarry volume monitoring case study, you can see an application of the DEM files created in 3DF Zephyr related to an applied scenario.