IN THIS ARTICLE
Image coordinate system
GCPs coordinate system
Project coordinate system
Arbitrary coordinate system
Horizontal grid corrections and transformations
Image coordinate system
The image coordinate system is:
- Automatically set to WGS84 - EPSG:4326, for the horizontal image coordinate system. 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.
- Automatically set based on the xmp tag Xmp.Camera.HorizCS and Xmp.Camera.VertCS if they are available. More in the EXIF and XMP tag information read by Pix4D article.
- Manually selected when using the Import image geolocations and orientations... feature.
For more information, please see our 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, please see our 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 coordinate system is not defined, 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 set to ellipsoidal heights*.
- When GCPs coordinate system is defined, 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.
Arbitrary coordinate system
Arbitrary or local coordinate systems are typically used in constructions sites, or in mining. The origin of the system is based on arbitrary (local) points and is not aligned with any known coordinate system.
In PIX4Dmatic, Ground Control Points (GCPs) with arbitrary coordinates can be used to georeference the project in an arbitrary coordinate system.
Select the Arbitrary CRS and units (m, ft, ftUS) of the GCPs.
The recommended workflow [Method - A] is to:
- Create a project and import images.
- In the Select the GCP coordinate reference system (CRS), click Arbitrary CRS and select the units.
- Import the GCPs.
- Mark GCPs on images.
- Run Calibrate step.
The alternative workflow [Method - B] is to:
- Create a project and import images.
- In the Select the GCP coordinate reference system (CRS), click Arbitrary CRS and select the units.
- Run Calibrate step.
- Mark at least 3 MTPs in the exact area where the GCPs appear.
- In the Tie Points table, change the type of marked MTP to GCPs and manually insert their coordinates.
- Rename the MTPs to the actual name of the GCP in the import file.
- Rerun the Calibrate step by selecting the Reoptimize cameras.
- Import and mark additional GCPs.
- Rerun the Calibrate step by selecting the Reoptimize cameras.
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.
Article feedback (for troubleshooting, post here instead)
0 comments