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.

**IN THIS ARTICLE**

Working with GCPs with Pix4Dmapper

Working without GCPs with Pix4Dmapper

Working directly on Pix4Dcloud / Pix4Dcloud Advanced

Special characteristics of Pix4Dcloud projects with arbitrary systems

Limitations of projects with arbitrary systems

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

## Working with GCPs with Pix4Dmapper

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

## Working without GCPs with Pix4Dmapper

- 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.
- In Pix4Dmapper, create a new project.
- 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). - Upload the project to be processed on Pix4Dcloud.

## Working directly on Pix4Dcloud / Pix4Dcloud Advanced

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).

Arbitrary coordinates |
Absence of WGS84 coordinates |
No OpenLayers map |

## Limitations of projects with arbitrary systems

The AutoGCPs detection functionality does not support arbitrary systems.

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