FAQ PIX4D-adapted RTK devices - PIX4Dcatch

What is a Pix4D-adapted RTK device?

PIX4D adapted RTK devices for use with Pix4D can be attached to certain Apple or Android devices. When paired with Pix4Dcatch, these devices can geotag images with RTK precision as they are captured. This synchronization allows for real-time connection to NTRIP services, ensuring absolute accuracy for 3D photogrammetry scans.

Extensive research has revealed that it is possible to achieve 3D models with an absolute geolocation accuracy of less than 5 cm. More information is in the white paper.

The hand-held RTK devices replaces more expensive ground surveying equipment that does not compromise on accuracy to achieve 3D, actionable results.

How to use the Pix4Dcatch with a Pix4D-adapted RTK device?

Basic requirements:

  • Pix4Dcatch app.
  • Pix4D-adapted RTK device.
  • NTRIP service subscription.
  • Internet access.
  • PIX4Dmatic, Pix4Dmapper, or Pix4Dcloud (Advanced) license or trial for processing.

Once the latest version of Pix4Dcatch is installed, select the Pix4D-adapted RTK device via Bluetooth settings. More information in the How to use Pix4Dcatch with Pix4D-adapted viDoc RTK devices article.

What are the recommended devices?

iPhone 15 Pro
iPhone 14 Pro
iPhone 14 Pro Max
iPhone 13 Pro
iPhone 13 Pro Max
iPhone 12 Pro
iPhone 12 Pro Max
iPad Pro 11-inch (2nd gen and later)*
Any iPhone device with an iOS version 16.0
Any iPad 11-inch (2nd gen and later) device with an iOS version 16.0
Any iPad 12.9-inch (2nd gen and later) device with an iOS version 16.0
Any Android device with ARCore and Depth API capability**
Any Android device with ARCore capability

*Wi-Fi-only iPad models do not contain an internal GPS. This may result in projects not being geolocated unless used with the Pix4D-adapted viDoc RTK rover or GCPs.

**LiDAR is not supported on Android

How are the images captured in Pix4Dcatch synchronized with the Pix4D-adapted RTK devices?

The image acquisition in Pix4Dcatch is independently done from the recording of the GNSS data from the RTK rover. When the capture is complete and the project is saved, the geolocation information from the rover is tagged to the corresponding images based on the image timestamps. The orientation of the images is computed based on information from the AR tracking. If part of the GNSS data has low accuracy (for example, due to poor satellite visibility), relative AR positioning is used to improve the positions and accuracy.

How are the orientations of images set when using Pix4Dcatch+Pix4D-adapted RTK devices?

The orientation of the geotagged images is indirectly computed from the internal IMU (Inertial Measurement Unit) of the mobile device and not from the Pix4D-adapted RTK devices.

Is the offset between the rover's antenna and the camera taken into account?

The offset is taken into account for select Apple devices. For more information: Recommended devices.

It is necessary to measure and enter the offset when pairing with an Android device. For more information: How to measure the offset - PIX4Dcatch (Android) with Pix4D-adapted RTK devices.

Can I generate a 3D model or 2D map in a coordinate reference system of my choice using Pix4Dcatch+Pix4D-adapted devices?

It is possible to select the coordinate system when uploading to PIX4Dcloud/PIX4Dcloud Advanced, in PIX4Dmatic or Pix4Dmapper, to get the 3D model or 2D map in a coordinate reference system of your choice. You can also transform the image geolocation in the desired coordinate system with third-party software.

For more information:

What is the height reference of the geolocated images and how can I change it?

The height is based on the ellipsoid of the input horizontal coordinate reference system.

Example: The input coordinate reference system has to match the coordinate reference system the NTRIP service broadcasts corrections. We have identified several input coordinate reference systems used from various regions and the associated ellipsoid.
Input coordinate reference system
Ellipsoidal height over the:
Europe - ETRS 89 (EPSG: 4258)
GRS 1980 ellipsoid
United States - NAD83(2011) (EPSG: 6318)
GRS 1980 ellipsoid
Japan - JGD2001 (EPSG:6668)
GRS 1980 ellipsoid
Singapore - SVY21 (EPSG:4757)
WGS 84 ellipsoid

For more information: How to use PIX4Dcatch with the Pix4D-adapted viDoc RTK devices.

In order to get the results georeferenced based on the local geoid, you can:

Will tilting the device during data acquisition have an impact on the accuracy of the 3D models?

The antenna on the Pix4D-adapted viDoc RTK devices has the best visibility of satellites when it is directly pointing upwards (90 degrees). The more the antenna is tilted from the 90-degree position, the lower its accessibility to satellites. Hence, it is recommended to only slightly tilt the device from the ideal 90-degree position to a maximum of 20 degrees.

How precisely is the RTK trajectory synchronized with the images?

The images acquired from Pix4Dcatch+Pix4D-adapted devices should be precisely synchronized to within 100ms.

Please ensure that the device clock is synchronized. To synchronize the clock in your iPhone or iPad:

  • Open the Settings app.
  • Tap "General."
  • Tap "Date & Time."
  • Verify that "Set Automatically" is toggled to the right and appears green.

Can Pix4D-adapted viDoc RTK devices for Pix4Dcatch be used without an internet connection?

An internet connection is needed during data capture to stay connected to the NTRIP service.

An internet connection is also needed every time Pix4Dcatch is started for logging into the app and uploading the data to Pix4Dcloud for generating the 3D model.

Can I do PPK or use my own base station?

At the momento the Pix4D-adapted RTK devices only allows access to an NTRIP service to receive real-time correctional GNSS data. It is not possible to do PPK or to connect to your own base station.

Can I accurately acquire data with Pix4Dcatch + Pix4D-adapted RTK devices over time?

Yes, Pix4Dcatch with Pix4D-adapted RTK devices allows to capture and process a 4D model and visualize it on Pix4Dcloud Advanced's timeline. Due to the RTK accuracy, the 3D models at different times are registered with cm accuracy. You can use Pix4Dcloud Advanced sliders to compare orthomosaics or track volume changes of small stockpiles.

Can I combine RTK drone data and terrestrial Pix4Dcatch + Pix4D-adapted RTK devices mobile phone data?

Drone RTK flights, as well as Pix4Dcatch RTK data, can be combined in a single project inside Pix4Dmapper to obtain a 3D model that has the overview and roof data (from drone imagery) as well as the terrestrial details (from Pix4Dcatch mobile phone data).

More information about how to process such datasets is in the How to merge projects article.

How can I purchase the Pix4D-adapted RTK devices?

Contact us directly for the purchase of the Pix4D-adapted RTK devices.

How can I get technical support for the Pix4D-adapted RTK devices?

Pix4D customers: For technical questions, contact our support team.

Not a customer yet? Contact sales or post on the Pix4D Community.

Battery care and maintenance.

The following recommendations will ensure optimum performance and extend the life of your batteries:

  • The battery is supplied partially charged. Fully charge the battery before using it for the first time.
  • Try not to allow the batteries to fully discharge.
  • Keep the battery charged continuously when not in use.
  • If you need to store the rover, fully charge it before storage and then charge it at least every three months.
  • To charge the battery, only use a charger/cable that is suitable for charging the lithium-ion battery.
  • If the unit has been stored for more than three months, charge the battery before using the receiver.
  • During operation, it is possible to charge the Pix4D-adapted RTK devices with a power bank when the battery status is low.

Which geoids are compatible with PIX4Dcatch and the RTK devices?

The following list contains the geoids available to PIX4Dcatch using the Pix4D-adapted RTK devices.

Important: Before selecting the Geoid, it is necessary to select the correct Vertical coordinate reference system. Only geoids corresponding to a certain vertical coordinate system are listed in the Geoid drop-down menu.

When selecting the vertical coordinate reference system, be sure the unit of measurement is the same as the horizontal coordinate reference system. e.g. ftUS/ftUS, meter/meter, not ft/ftUS, ft/meter etc.

Country or region
Vertical coordinate reference system
EGM2008 height - (EPSG:3855)
EGM96 height - (EPSG:5773)
SVD2006 - (EPSG: 20000)
AHD height - (EPSG:5711)
AHD (Tasmania) height - (EPSG:5712)
AHD height - (EPSG:5711)
AHD (Tasmania) height - (EPSG:5712)
AHD height - (EPSG:5711)
EVRF2000 Austria height - (EPSG: 9274)
Austrian Geoid 2008
Ostend height - (EPSG: 5710)
CGVD28 height - (EPSG:5713)
CGVD2013 height - (EPSG:6647)
CGVD2013(CGG2013a) height - (EPSG:9245)
Czechia and Slovakia
Baltic 1957 height - (EPSG: 8357)
Denmark - onshore
DNN height - (EPSG:5733)
DVR90 height - (EPSG:5799)
Faroe Islands - onshore
FVR09 height - (EPSG: 5317)
France - mainland onshore
NGF-IGN69 height - (EPSG:5720)
RAF09, RAF18, RAF18b, RAF20
France - Corsica onshore
NGF-IGN78 height - (EPSG: 5721)
Gibraltar - onshore and Spain - mainland onshore
Alicante height - (EPSG: 5782)
Greenland - onshore and offshore between 58°N and 85°N and west of 7°W
GVR2016 height - (EPSG: 8267)
Greenland - onshore and offshore between 59°N and 84°N and west of 10°W
GVR2000 height - (EPSG: 8266)
Iceland - onshore
ISH2004 height - (EPSG: 8089)
Ireland - onshore United Kingdom (UK) - Northern Ireland (Ulster) - onshore
Malin Head height - (EPSG: 5731)
Isle of Man - onshore
Douglas height - (EPSG: 5750)
Japan - onshore mainland - Hokkaido, Honshu, Shikoku, Kyushu
JGD2011 (vertical) height - (EPSG: 6695)
Switzerland and Liechtenstein
LN02 height - (EPSG:5728)
LN95 height - (EPSG:5729)
NAVD88 height - (EPSG: 5703)
Netherlands - onshore, including Waddenzee, Dutch Wadden Islands, and 12-mile offshore coastal zone
NAP height - (EPSG: 5709)
New Zealand
NZVD2009 height - (EPSG:4440)
NZVD2016 height - (EPSG:7839)
Northern Mariana Islands - onshore - Rota, Saipan, and Tinian
NMVD03 height - (EPSG:6640)
Norway - onshore
NN54 height - (EPSG:5776)
NN2000 height - (EPSG:5941)
EVRF2007-PL height - (EPSG:9651)
Baltic 1986 - (EPSG:9650)
Puerto Rico - onshore
PRVD02 height - (EPSG:6641)
South Africa - onshore
SA LLD height - (EPSG: 9279)
Spain - Balearic Islands - Ibiza and Formentera
Ibiza height - (EPSG:9394)
Spain - Balearic Islands - Mallorca
Mallorca height - (EPSG:9392)
Spain - Balearic Islands - Menorca
Menorca height - (EPSG:9393)
Spain - Canary Islands - El Hierro
El Hierro height - (EPSG:9401)
Spain - Canary Islands - Fuerteventura
Fuerteventura height - (EPSG:9396)
Spain - Canary Islands - Gran Canaria
Gran Canaria height - (EPSG:9397)
Spain - Canary Islands - La Gomera
La Gomera height - (EPSG:9399)
Spain - Canary Islands - La Palma
La Palma height - (EPSG:9400)
Spain - Canary Islands - Lanzarote
Lanzarote height - (EPSG:9395)
Spain - Canary Islands - Tenerife
Tenerife height - (EPSG:9398)
Spain - Ceuta
Ceuta 2 height - (EPSG:9398)
St Helena, Ascension, and Tristan da Cunha - St Helena Island - onshore
SHVD2015 height - (EPSG: 7890)
Sweden - onshore
RH2000 height - (EPSG: 5613)
United Kingdom (UK)
ODN height - (EPSG:5701)
United Kingdom (UK) - Great Britain - England - Isles of Scilly onshore
St Marys height - (EPSG:5749)
United Kingdom (UK) - Great Britain - Scotland - Orkney Islands onshore
ODN Orkney height - (EPSG:5740)
United Kingdom (UK) - Great Britain - Scotland - Outer Hebrides onshore
Stornoway height - (EPSG:5746)
United Kingdom (UK) - Great Britain - Scotland - Shetland Islands onshore
Lerwick height - (EPSG:5742)
United Kingdom (UK) - Northern Ireland (Ulster) - onshore
Belfast height - (EPSG:5732)
United Kingdom (UK) – offshore between 2km from shore and boundary of UKCS within 49°46'N to 61°01'N and 7°33'W to 3°33'E
ODN (Offshore) height - (EPSG:7707)
United States (USA)
NAVD88 height (US Survey foot) - (EPSG: 6360)
United States (USA) - onshore - Arizona, Michigan, Montana, North Dakota, Oregon, South Carolina
NAVD88 height (foot) - (EPSG: 8228)
United States (USA)
NAVD88 height - (EPSG: 5703)
US Virgin Islands - onshore - St Croix, St John, and St Thomas
VIVD09 height - (EPSG: 6642)
American Samoa - Tutuila island
ASVD02 height - (EPSG: 6643)
Guam - onshore
GUVD04 height - (EPSG: 6644)

* Geoid not available in PIX4Dcloud / PIX4Dcloud Advanced