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

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The number of points that are generated during step 2. Point Cloud and Mesh depends 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

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.
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### Article feedback (for troubleshooting, post here instead)

• Steve Richmond

Does the Image Scale affect the quality of the point density?  Will I get better accuracy if I process at Original Image size set on Optimal as opposed to 1/2 Half Image Size set on High?  The output point densities are the same and the time to process is the same.

Edited by Steve Richmond
• Momtanu (Pix4D)

Hi Derek,