Processing options
      Back to home
      1. Pix4D Documentation
      2. PIX4Dmatic
      3. Processing options

      DSM - PIX4Dmatic

       

      Pix4Dmatic raycloud icon

      Calibrate

      Pix4Dmatic point cloud icon

      Point cloud

      PIX4Dmatic_mesh_icon.png

      Mesh

      Pix4Dmatic dsm icon

      DSM

      Pix4Dmatic orthomosaic icon

      Orthomosaic

      DSM

      The DSM step defines the Resolution, enables the Surface smoothing, and enables Interpolation for the digital surface model (DSM) creation.

      Access:
      • Click Processing options processing_options.png.
      • On the Menu bar, click Process > DSM...

      It allows users to change the following processing options:

      Input

      Important: For PIX4Dcatch projects that contain LiDAR depth maps it is possible to select either the Depth or Depth and dense point cloud to generate the DSM. 

      This processing option defines which input source is used for the DSM generation. The following options are available:

      • Dense point cloud
      • Depth point cloud (PIX4Dcatch projects)
      • Depth & dense fusion (PIX4Dcatch projects)
      • Automatic tie points (Starting from the 1.69.0 version of PIX4Dmatic)

      Tip: Selecting Automatic Tie Points as the input for DSM generation can be useful for relatively flat projects with minimal 3D structures (e.g., buildings, bridges). This option was introduced to speed up the DSM generation process for such projects while maintaining the same level of absolute accuracy (.i.e the position with respect to the GCPs/Checkpoints). 

      Resolution

      Defines the spatial resolution used to generate the DSM. The default resolution is determined based on the calculated average Ground Sampling Distance (GSD) of the project.

      • Resolution [units/px]: Defines the resolution of the DSM.
        • Default: The resolution is 1 x GSD of the project.
        • Custom: Allows to select any value for the resolution of the DSM.

      Surface smoothing

      The surface smoothing is applied to the generated DSM. When using Low values, the final DSM contains sharper features and edges. When using High values, the DSM is smoothed out.

      • Surface smoothing (0 - 20, 12 - default): The radius of the median filter can be selected to determine the effect of DSM smoothing:
        • 0: No smoothing is applied.
        • Low (values closer to 1): Tries to preserve the orientation of the surface and to keep sharp features such as corners and edges of buildings.
        • High (values closer to 20): Tries to smooth areas based on a larger surrounding area. Sharp edges will be smoothed out. Areas that are not very planar are smoothed and become planar.
      Important: The DSM receives its input as the dense point cloud. If the dense point cloud is noisy, this will be directly reflected in the generated DSM. Make sure that the results of the Calibrate and Densify steps are optimal before generating the DSM.

      Interpolation

      The Interpolation parameters affect the completeness of the generated DSM:

      • Interpolation - Enabled (Default): The entire area of the DSM is filled. Areas with missing data in the dense point cloud are filled based on the neighboring points.
      • Interpolation - Disabled: Only areas where the dense point cloud is generated are reconstructed in the DSM model. Where the dense point cloud is not generated or is not dense enough holes in the DSM appear.
      Example: The influence of the DSM - Interpolation parameter on the results:

      Pix4Dmatic_DSM_interpolation_off.jpg

      Pix4Dmatic_orthomosaic_interpolation_off.jpg

      Pix4Dmatic_DSM_interpolation_on.jpg

      Pix4Dmatic_orthomosaic_interpolation_on.jpg

      Note: When using Interpolation - Enabled, the entire area of the project is filled and a continuous surface is generated. Since the surface is approximated with neighboring points some inaccuracies are expected.

      Exports

      The following export settings are available:

      • Compression (LZW compression, Enabled - default): Defines the compression of the exported file.
        • LZW compression - Enabled: No data is lost during the compression of the file and the .tiff is not degraded. This results in a smaller file size of the exported file.
        • LZW compression - Disabled: No compression is used during the export. This results in a larger file size of the exported file.
      • File Type (Single - default):
        • Single: The image will be exported in a single file.
        • Tiles (2048 px - default): The image will be exported in tiles with a predefined size of 1024 px, 2048 px, or 4096 px. The origin of the tiles is the top left corner of the project boundary.
      • Image Scale (100%- default): Defines the scale of the exported file.
        • 100%: The exported image will keep the original size.
        • 50%: The exported image will be scaled to 50% of the original size.
        • 25%: The exported image will be scaled to 25% of the original size.
          Example: For a file with the original size of 10000 x 10000 pixels, the exported file with Image scale:
          • 100%: 10000 x 10000 pixels.
          • 50%: 5000 x 5000 pixels.
          • 25%: 2500 x 2500 pixels.
      • Save as...:
        • Single: Specifies the path and the file name of the exported file.
        • Tiles: Specifies the destination folder.

      To export the DSM automatically after the DSM step:

      • In Processing options > Exports, select the DSM GeoTIFF option.
      • (Optional) Click ... and specify the export settings.
      • Click Start.
      Note: It is possible to export the DSM without re-running DSM process:
      • On the Menu tab, click File > Export DSM...
      • In the Export DSM dialog, select the export settings.
      • Click Export.