viDoc RTK rover for Pix4Dcatch - FAQ

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What is the viDoc RTK rover?

The viDoc RTK rover is a device that can be mounted onto select Apple and Android devices. The rover, synchronized with Pix4Dcatch, geotags images with RTK accuracy in real-time, while connected to any NTRIP service, allowing absolute accuracy in 3D photogrammetric scanning.

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.

Conceived by viGram GmbH., a German company led by professional surveyors, the viDoc RTK rover is designed with an eye for accuracy and works with Pix4Dcatch for image acquisition. The hand-held RTK rover is a replacement for more expensive ground surveying equipment that does not compromise on accuracy to achieve 3D, actionable results.

For more information see viDoc RTK rover product page.

How to use the Pix4Dcatch with viDoc RTK rover?

Basic requirements:

  • Pix4Dcatch app.
  • viDoc RTK rover.
  • 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 viDoc RTK via Bluetooth settings. More information in the How to use Pix4Dcatch with viDoc RTK rover article.

What are the recommended devices?

How are the images captured in Pix4Dcatch synchronized with the viDoc RTK rover?

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. In case 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+viDoc RTK rover?

The orientation of the geotagged images is indirectly computed from the internal IMU (Inertial Measurement Unit) of the mobile device and not from the viDoc RTK rover.

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 viDoc RTK rover.

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

Yes, you can 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 in. 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 viDoc RTK rover.

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 viDoc RTK rover 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+viDoc should be precisely synchronized to within 100ms.

Please ensure that the device clock is synchronized. In order 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 viDoc RTK rover for Pix4Dcatch be used without an internet connection?

No, you need an internet connection 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?

The viDoc RTK rover 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 + viDoc RTK rover over time?

Yes, Pix4Dcatch with viDoc RTK rover 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 + viDoc 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 viDoc RTK Rover?

Contact us directly for the purchase of the viDoc RTK rover.

How can I get technical support for the viDoc RTK rover?

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

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

Which geoids are compatible with PIX4Dcatch and the viDoc RTK rover?

The following list contains the geoids available to PIX4Dcatch using the viDoc RTK rover.

 
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 Geoid
Global EGM2008 height - (EPSG:3855) EGM2008
EGM96 height - (EPSG:5773) EGM96
Australia AHD height - (EPSG:5711)
AHD (Tasmania) height - (EPSG:5712)
AUSGeoid98
AHD height - (EPSG:5711)
AHD (Tasmania) height - (EPSG:5712)
AUSGeoid09
AHD height - (EPSG:5711) AUSGeoid2020
Austria EVRF2000 Austria height - (EPSG: 9274) Austrian Geoid 2008
Canada CGVD28 height - (EPSG:5713) CGG2000/HTv2.0
CGVD2013 height - (EPSG:6647) CGG2013
CGVD2013(CGG2013a) height - (EPSG:9245) CGG2013a
Czechia and Slovakia Baltic 1957 height - (EPSG: 8357) DVRM05
Denmark - onshore DNN height - (EPSG:5733) DNN
DVR90 height - (EPSG:5799) DVR90
Faroe Islands - onshore FVR09 height - (EPSG: 5317) FVR09
France - mainland onshore NGF-IGN69 height - (EPSG:5720) RAF09
RAF18
France - Corsica onshore NGF-IGN78 height - (EPSG: 5721) RAC09
Gibraltar - onshore and Spain - mainland onshore Alicante height - (EPSG: 5782) EGM08-REDNAP
Greenland - onshore and offshore between 58°N and 85°N and west of 7°W GVR2016 height - (EPSG: 8267) GGEOID2016
Greenland - onshore and offshore between 59°N and 84°N and west of 10°W GVR2000 height - (EPSG: 8266) GGEOID2000
Iceland - onshore ISH2004 height - (EPSG: 8089) IceGeoid2011
Ireland - onshore United Kingdom (UK) - Northern Ireland (Ulster) - onshore Malin Head height - (EPSG: 5731) OSGM15
Isle of Man - onshore Douglas height - (EPSG: 5750) OSGM15
Japan - onshore mainland - Hokkaido, Honshu, Shikoku, Kyushu JGD2011 (vertical) height - (EPSG: 6695) GSIGEO2011
Switzerland and Liechtenstein LN02 height - (EPSG:5728) CHGeo2004
LN95 height - (EPSG:5729)
Mexico NAVD88 height - (EPSG: 5703) GEOID03, GEOID06, GEOID09, GEOID12A, GEOID12B, GEOID18, GEOID99, GGM10
Netherlands - onshore, including Waddenzee, Dutch Wadden Islands, and 12-mile offshore coastal zone NAP height - (EPSG: 5709) NLGEO2018
New Zealand NZVD2009 height - (EPSG:4440) NZGeoid2009
NZVD2016 height - (EPSG:7839) NZGeoid2016
Northern Mariana Islands - onshore - Rota, Saipan, and Tinian NMVD03 height - (EPSG:6640) GEOID12A
GEOID12B
Norway - onshore NN54 height - (EPSG:5776) HREF2008a
NN2000 height - (EPSG:5941) HREF2018b
Puerto Rico - onshore PRVD02 height - (EPSG:6641) GEOID12A
GEOID12B
GEOID18
South Africa - onshore SA LLD height - (EPSG: 9279) SAGEOID2010*
Spain - Balearic Islands - Ibiza and Formentera Ibiza height - (EPSG:9394) EGM08-REDNAP
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) EGM2008
Sweden - onshore RH2000 height - (EPSG: 5613) SWEN17
United Kingdom (UK) ODN height - (EPSG:5701) OSGM15
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) GEOID03, GEOID06, GEOID09, GEOID12A, GEOID12B, GEOID18, GEOID99, GGM10*
United States (USA) - onshore - Arizona, Michigan, Montana, North Dakota, Oregon, South Carolina NAVD88 height (foot) - (EPSG: 8228)
United States (USA) NAVD88 height - (EPSG: 5703)
Mexico
US Virgin Islands - onshore - St Croix, St John, and St Thomas VIVD09 height - (EPSG: 6642) GEOID12A, GEOID12B, GEOID18
American Samoa - Tutuila island ASVD02 height - (EPSG: 6643) GEOID12A, GEOID12B
Guam - onshore GUVD04 height - (EPSG: 6644) GEOID12A, GEOID12B

* Geoid not available in PIX4Dcloud / PIX4Dcloud Advanced

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