How to generate the contour lines

 
 Important:
  • Step 1. Initial processing should be processed and it is recommended that step 2. Point Cloud and Mesh is processed as well.
  • The generation of contour lines is not included in any default processing template.
  • Consider drawing a processing area at least before step 3. DSM, Orthomosaic and Index to restrict the area covered by contour lines.
 
Video: Watch the instructional video related to Contour Lines and DTM:
   

What are contour lines?

Contour lines are lines connecting points of equal elevation. They give a better understanding of the variations in elevation of the land surface or topography of a project area.

Contour lines can be generated with the digital surface model (DSM) or the digital terrain model (DTM). The extent and highest resolution possible of the contour lines will depend on the source layer.

Generated with the digital surface model

Generating contour lines with the digital surface model (DSM) is recommended when there are no objects on the project's surface, such as high vegetation or buildings.

You can achieve a high level of detail in the contour lines because the DSM can have a resolution as high as the average ground sampling distance (GSD) of the project. 

Digital surface model Contour lines using the digital surface model

Generated with the digital terrain model

Generating contour lines with the digital surface model (DTM) is recommended when there are objects on the project's surface, such as high vegetation or buildings.

You can achieve a moderate level of detail in the contour lines because the DTM can have a resolution as high as five times the average ground sampling distance (GSD) of the project.

Digital terrain model  Contour lines using the digital terrain model

 

 
Information: Contour lines are automatically stored in the results folder ...\project_name\3_dsm_ortho\extras\contours.
  • Under project_name_interval_resolution_minimum_line_size_DSM if the contour lines are generated with the DSM.
  • Under project_name_interval_resolution_minimum_line_size_DTM if the contour lines are generated with the DTM.
  • As a consequence, contour lines generated with the same source layer and with the same options will be automatically overwritten.

During processing step 3. DSM, Orthomosaic and Index with the digital surface model

      1. On the menu bar, click Process > Processing Options...
      2. Click 3. DSM, Orthomosaic and Index.
      3. Select the tab DSM and Orthomosaic.
      4. In the section Raster DSM, make sure that GeoTIFF and Merge Tiles are selected.
      5. Select the tab Additional Outputs
      6. In the section Contour Lines, check the box next to the desired output format(s).
      7. If necessary, change the Elevation Interval [unit], Resolution [cm] and Minimum Line Size [vertices] values. For more information about the contour lines options: Menu Process > Processing Options... > 3. DSM, Orthomosaic and Index > Additional Outputs.
      8. Click OK.
      9. On the menu bar, click View > Processing.
      10. Check the box next to 3. DSM, Orthomosaic and Index.
      11. Click Start.
 
Important: If the options Raster DTM GeoTIFF and Merge Tiles are selected before processing step 3. DSM, Orthomosaic and Index, the DTM will be used to generate contour lines and the DSM will be ignored. It is, however, possible to generate contour lines with the DSM after processing step 3. DSM, Orthomosaic and Index.

During processing step 3. DSM, Orthomosaic and Index with the digital terrain model

  1. On the menu bar, click Process > Processing Options...
  2. Click 3. DSM, Orthomosaic and Index.
  3. Select the tab DSM and Orthomosaic.
  4. In the section Raster DSM, make sure that GeoTIFF and Merge Tiles are selected.
  5. Select the tab Additional Outputs
  6. In the section Raster DTM, select GeoTIFF and Merge Tiles.
  7. In the section Contour Lines, check the box next to the desired output format(s).
  8. If necessary, change the Elevation Interval [unit], Resolution [cm] and Minimum Line Size [vertices] values. For more information about the contour lines options: Menu Process > Processing Options... > 3. DSM, Orthomosaic and Index > Additional Outputs.
  9. Click OK.
  10. On the menu bar, click View > Processing.
  11. Check the box next to 3. DSM, Orthomosaic and Index.
  12. Click Start.
 
Important: It is possible to generate contour lines with the DSM after processing step 3. DSM, Orthomosaic and Index.

After processing step 3. DSM, Orthomosaic and Index

 
Access:
  • Step 3. DSM, Orthomosaic and Index must be processed.
  • The digital surface model (DSM) has to have been exported in the GeoTIFF format and the tiles merged.
  1. On the menu bar, click ProcessProcessing Options
  2. Click 3. DSM, orthomosaic and Index.
  3. Click the tab Additional outputs.
  4. Under the section Contour Lines, check the box next to one or several file formats.
     
    Tip: At first, you can consider generating contour lines in the PDF format only in order to visualize the results quickly. Then, generate the contour lines in the final format(s) when you are pleased with the results. Generating contour lines in the PDF format is relatively fast.
  5. [if necessary] Under the section Contour Lines, select values for Elevation Interval [m], Resolution, and Minimum Line Size [vertices].
  6. On the menu bar, click ProcessGenerate contour lines (DSM) or click ProcessGenerate contour lines (DTM).
     
    Access: The digital terrain model (DTM) has to have been exported in the GeoTIFF format and the tiles merged.
Was this article helpful?
21 out of 24 found this helpful

Article feedback (for troubleshooting, post here)

6 comments

  • Bruno ROY

    Bonjour,

    Comment faire pour voir les courbes de niveaux sur l'orthophoto, le MNS, et le MNT ?

     

  • Blaž (Pix4D)

    Hi Bruno,

    Currently, there is no option to overlay the contour lines over the orthomosaic, DSM or DTM in Pix4Dmapper. You can do this in any GIS software such as QGIS. You can also do this using Google earth pro. If you generate google earth tiles and .shp files for the contour lines then you can import these into google earth and show one over the other. Pix4D is primarily a data processing engine that is meant to produce useful data products that can be input into various workflows. 

    Best,

  • Jared Buckley

    Would be great to be able to have contours as a layer when viewing projects in the cloud

  • Holden (Pix4D)

    Hi Jared. I can see that being a useful feature. I would suggest letting our developers know you would like to see this feature by submitting it on the feature suggestion page. Thanks for helping improve Pix4D!

    https://community.pix4d.com/c/feature-request

  • Nick Bilz

    I collected data on a property using a drone, processed the data, and am now trying to understand the results, specifically the numeric value assigned to the contour lines. Is it arbitrary/random or does the value actually mean something? There are positive and negative numbers in the attribute table, and I know the numbers can't be referring to sea level or absolute elevation as this property isn't possibly at or below sea level. So, what do the numbers mean?

  • Holden (Pix4D)

    Hi Nick. The units will be whatever you selected for your output coordinate system. The unexpected values are likely due to inaccuracies from the drone GPS. If you need accurate elevation data you should use GCPs. 

Please sign in to leave a comment.