How to work with arbitrary systems on Pix4Dcloud

In certain environments, such as construction sites, it is common to work with a user-defined coordinate system, specified by an origin and the direction of two X,Y axes. This article explains how to define an arbitrary system when using Pix4Dcloud.

There are three ways to obtain a project in an arbitrary coordinate system on Pix4Dcloud.

Working with GCPs with Pix4Dmapper

  1. In Pix4Dmapper, create a project. Import the images and configure the image properties. More information in Step 2. Creating a Project.
  2. Select Arbitrary as output coordinate system.
  3. Import the GCPs and define the GCP coordinate system as Arbitrary.
  4. Mark the GCPs by using the Basic GCP/MTP Editor.
  5. Once the GCPs have been marked, upload the project to be processed on Pix4Dcloud.

Working without GCPs with Pix4Dmapper

  1. Compute the seven parameters transformation from WGS84 to the user-defined coordinate system as explained in How to compute the Site Calibration for GCPs in an Arbitrary Coordinate System.
  2. In Pix4Dmapper, create a new project. 
  3. As output coordinate system, select Arbitrary and apply the seven parameters transformation computed at step 1 (more information in How to use the Site Calibration Parameters).
  4. Upload the project to be processed on Pix4Dcloud.

Working directly on Pix4Dcloud / Pix4Dcloud Advanced

 
Note: Uploading from Pix4Dmapper is the only way to work in a user-defined arbitrary coordinate system.

When uploading images without geolocation, Pix4Dcloud / Pix4Dcloud Advanced will automatically set up the output coordinate system to Arbitrary.

This is not recommended as the arbitrary system will be randomly defined:

  • Datasets will have no scale and will be located in a fictitious location
  • If they belong to a site
    • Each dataset will be in a fictitious location
    • Datasets will not be aligned 

Special characteristics of Pix4Dcloud projects with arbitrary systems

  • The coordinate system is defined as Arbitrary (units) in the 2D/3D view.
  • No WGS84 latitude, longitude coordinates are displayed in the 2D/3D view.
  • As the coordinates are arbitrary, there is no OpenLayers map as background.
  • Unlike other projects with standard coordinate systems, the annotations are exported in that arbitrary system and not in WGS84 (latitude, longitude). 

Pix4Dcloud_arbitrary_coordinates.jpg

Arbitrary coordinates

Pix4Dcloud_arbitrary_no_wgs84_coordinates.jpg

Absence of WGS84 coordinates

Pix4Dcloud_arbitrary_no_OpenLayers_background_map.jpg

No OpenLayers map

Limitations of projects with arbitrary systems

The AutoGCPs detection functionality does not support arbitrary systems.

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