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      How many Points are generated during step 2. Point Cloud and Mesh? - PIX4Dmapper

      This article displayed the average number of points that may be generated during step 2. Point Cloud and Mesh in PIX4Dmapper.

      The number of points that are generated during step 2. Point Cloud and Mesh depend on several factors such as the image size, image content, image overlap, and processing options. Therefore, it is not possible to precisely estimate the number of points generated during step 2. However, some statistics about the number of points of the point cloud could be made and are shown below.

      Estimated number of points observed in projects with 14 MP images

      The used options for step 2. Point Cloud and Mesh:

      • Image Scale is 1/2 (Half image size).
      • Point Density is Optimal.
      • Minimum number of Matches: 3
      Number of images
      Number of points
      LAS file size
      250
      20 - 50 million
      0.3 - 1.0 GB
      500
      40 - 60 million
      1.2 - 1.9 GB
      1000
      80 - 120 million
      2.5 - 3.8 GB
      Note:
      • The size of the LAS file depends on the number of points. One point will take 34 bytes disk space.
      • The above-mentioned numbers are only estimates and depend on the image size and content. For example, urban areas projects will have more points than desert or snow area projects.

      Estimated impact of processing options on the number of points generated

      There are 2 processing options for step 2. Point Cloud and Mesh that have an impact on the number of points generated:

      • Image Scale
      • Point Density

      For more information about the processing options: Menu Process > Processing Options... > 2. Point Cloud and Mesh > Point Cloud.

      The following table summarizes by which factor the number of points obtained with the default options changes when changing the Image Scale and Point Density.

      Image Scale \ Point Density
      1 (Original image
      size, Slow)
      1/2 (Half image
      size, Default)
      1/4 (Quarter image
      size, Fast)
      1/8 (Eighth image
      size, Tolerant)
      High (Slow)
      x16
      x4
      Same as default
      ÷4
      Optimal
      x4
      DEFAULT
      ÷4
      ÷16
      Low (Fast)
      Same as default
      ÷4
      ÷16
      ÷64
      Example: A project of 500 images of 14 MP generates a point cloud of 40 million points using the default options. The following table displays how many points are generated depending on the selected processing options.
      Image Scale \ Point Density
      1 (Original image
      size, Slow)
      1/2 (Half image
      size, Default)
      1/4 (Quarter image
      size, Fast)
      1/8 (Eighth image
      size, Tolerant)
      High (Slow)
      640 million
      160 million
      40 million
      10 million
      Optimal
      160 million
      40 million
      10 million
      2.5 million
      Low (Fast)
      40 million
      10 million
      2.5 million
      0.625 million
      Note: The default processing parameters give already a high quality point cloud. Increasing the number of points generated by the default parameters does not necessarily increase the quality of the point cloud.