Tutorial #A05 : DEM Generation and Elevation Profile

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!

• 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 use 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;
• generate Elevation Profiles

 

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

 
As an example for this tutorial, we will use the public dataset linked below:

Dataset Download – Mining site (642 MB)

• Step 1 – DTM and DSM generation

This step matches the “Orthophoto generation Tutorial” as you require to generate an Orthophoto before creating any DSM/DTM. Click on Workflow (1) and True Orthophoto from Mesh (2). The Orthophoto Wizard creator (3) will open.

 

Once you have selected the Generation method (4) (by Axis, by Control points, or using the Current view) and clicked the Next (5) button, please check the Export section on the orthophoto’s settings page:

Besides the “Export orthophoto” option, you can enable either the DSMs/DTMs export options or both (6). As for the DSM export, you can choose the Elevation axis. The DTM export options enable a further checkbox to select the scene type according to the terrain’s shape (flat terrain, complex scene, and mountain area) (7). When you are done, simply click the Generate Orthophoto (8) button and choose the file name and path as well as the image file format.

• Step 2 – DEM Viewer overview

The DEM viewer will automatically appear when the computation is completed. It allows seeing the DEM you have just created directly inside 3DF Zephyr (see image below).

The DEM viewer menu comes with the following options:

– The File (4) menu includes the:

• Open from files option: it loads both DEM files and orthophotos (even those not related to the project you are working on).
• 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.

– The View (5) menu allows to select:

• The Band options: displays the DSM or the DTM (if both have been created).
• The Rendering Orthophoto option: Enables/disables the orthophoto view under the DEM.
• The Colormap option: allows to change the Colormap type, inverts the colors, and Set Colormap Levels between 4 and 256.
• The Show Polylines option: enables the Polylines view (sections, contour lines, or drawing elements) if they have been created.

– The Tools (6) menu allows to select:

• The Enable measure tool: which activate the cursor for placing points on the the DEM and take measurements
• The Elevation profile tool: which activates the cursor for placing points on the the DEM and create the Elevation profile.

– The Color bar (7) on the left side of the DEM viewer allows for setting the elevation range thanks to the minimum and maximum elevation thresholds.
 

Note: that the DEM viewer can be run at any time from the 3DF Zephyr menu bar: Utilities (1) > Images (2) > DEM viewer Utility (3).

• Step 3 – Elevation Profile Creation

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 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.
 

• Final notes

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.