**IN THIS ARTICLE**

Image coordinate system

GCPs coordinate system

Project coordinate system

Horizontal grid corrections and transformations

## Image coordinate system

The **horizontal image coordinate system** in Pix4Dmatic is automatically set to **WGS84** - EPSG:4326.

The vertical coordinate system is automatically defined based on the camera model of imported images:

- WGS84 - EPSG 7030 ellipsoid for images taken with DJI Phantom 4 RTK, senseFly AeriaX, S.O.D.A., S.O.D.A. 3D, and S.O.D.A. Corridor cameras.
- EGM96 - EPSG 5773 geoid model for all other camera models.

For more information see Which cameras are supported in Pix4Dmatic article

## GCPs coordinate system

Both the horizontal coordinate system and the vertical coordinate system can be defined in the *Tie Points* table:

To select the **horizontal coordinate reference system**:

- In the
*Horizontal coordinate reference system*dialog,**search or copy-paste**:- The name or
- The EPSG code of the coordinate system.

To select the** vertical coordinate reference system**:

- In the
*Vertical coordinate reference system*dialog,**search or copy-paste**:- The name or
- The EPSG code of the coordinate system.

- (Optional)
*Geoid:*If the selected vertical coordinate system supports geoids and the geoid model is available in the Pix4Dmatic database, select the geoid model in the drop-down list. - (Optional)
*Geoid height:*If the selected vertical coordinate system supports geoids but the geoid model is not available in the Pix4Dmatic database, enter the value of the geoid height at that location.

For more information and the list of supported geoids see How to use Geoids in Pix4Dmatic article.

## Project coordinate system

The horizontal and vertical coordinate system of the project is defined based on the imported image geolocation or based on selected GCPs coordinate system:

- When
**GCPs are not used**, the**project coordinate system is automatically defined**based on the position of the image geolocation. The corresponding**UTM zone is used**. The vertical coordinate system is always set to**ellipsoidal heights**. - When
**GCPs are used**, the**project coordinate system corresponds to the GCPs coordinate systems**. If the GCPs coordinate system is geographic the corresponding UTM zone is used for the project coordinate system.

## Horizontal grid corrections and transformations

Pix4Dmatic supports the most common horizontal grid corrections and transformations.

The corrections will be used automatically based on the selected coordinate systems.

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