FAQ - PIX4Dcatch

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What is PIX4Dcatch?

PIX4Dcatch is a mobile application for ground 3D scans from Android and iOS devices. PIX4Dcatch allows anyone to easily acquire the right terrestrial data for digitizing the reality around them and turning it into accurate 3D models.

Where can I download the PIX4Dcatch app?

To download the latest version of PIX4Dcatch, visit the App Store and Play Store.

What is the difference between PIX4Dcapture and PIX4Dcatch?

PIX4Dcapture is the flight planning and image acquisition app for aerial imaging, whereas PIX4Dcatch is a mobile application for ground 3D scans using iOS or Android devices.

Which operating system is supported by PIX4Dcatch?

PIX4Dcatch is currently supported on a device that runs on iOS version 14.1 or higher or on Android version 9 or higher.

Can PIX4Dcatch be used without an Internet connection?

An internet connection is needed every time the application is started for logging into the app. Once the login is complete, the internet connection is not necessary for capturing data. However, an internet connection is needed again to upload the project to PIX4Dcloud / PIX4Dcloud Advanced.

If using a viDoc RTK rover, you need an internet connection during data capture to stay connected to the NTRIP service.

What are the recommended devices?

  PIX4Dcatch only PIX4Dcatch with LiDAR PIX4Dcatch with viDoc RTK rover
iOS Any Apple iPhone or iPad* device (iOS 14.1 minimum) iPad Pro 2022*,
iPad Pro 2021*,
iPad Pro 2020*,
iPhone 14 Pro,
iPhone 14 Pro Max,
iPhone 13 Pro,
iPhone 13 Pro Max,
iPhone 12 Pro,
iPhone 12 Pro Max
iPad Pro 2022 (11in only),
iPad Pro 2021 (11in only),
iPad Pro 2020 (11in only),
iPhone 14 Pro,***
iPhone 14 Pro Max,***
iPhone 13 Pro,
iPhone 13 Pro Max,
iPhone 12 Pro,
iPhone 12 Pro Max,
iPhone 11 Pro,
iPhone 11 Pro Max,
iPhone XR
Android Any Android device with ARCore capability. Not supported Supported**

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

**It is necessary to measure and input the offset. For more information: How to measure the offset - PIX4Dcatch (Android) with viDoc RTK rover.

***The new iPhone 14 Pro models are compatible with PIX4Dcatch and the viDoc RTK rover. Until official camera offsets are provided, the iPhone 13 Pro model offsets will be applied. There appears to be a couple of millimeters difference between these two versions. This amount of error will be present until accurate measurements are provided.

Does the PIX4Dcatch app utilize LiDAR data (depth data) obtained from the device for processing?

PIX4Dcatch (iOS version) uses LiDAR to capture the depth information of the surrounding during the image acquisition. The LiDAR points will compensate for the lack of 3D points over reflective and low-texture surfaces. Processing with LiDAR data is the default option when uploading to PIX4Dcloud / PIX4Dcloud Advanced. Processing the exported project using PIX4Dmatic, the depth information can be used.

PIX4Dcatch (Android version) doesn't use depth data while processing.

When processing the exported project using PIX4Dmapper, the depth information will not be used. So, to use the depth data while processing, the project should be directly uploaded from the PIX4Dcatch app to the PIX4Dcloud, or exported and processed with PIX4Dmatic.

How does PIX4Dcatch utilize LiDAR data during image capturing and processing?

During the image acquisition, the LiDAR sensor has the following benefits:

  • Real-time feedback generated by the LiDAR sensor during capture guides you on the coverage of your area of interest.
  • Fine-tunes the positioning and pose information that automatically triggers the images.
  • It helps locate the project in the real world compared to the device’s internal GPS, which only gives a rough estimate.

In processing, the LiDAR data is used directly in two ways:

  • To estimate a more accurate scale of the reconstruction.
  • To fill low-texture areas that photogrammetry alone is not able to reconstruct.

It is important to note that visible features are still needed in all the images, even if the LiDAR data is used.

 
Example: Reflective and homogenous surfaces are challenging to reconstruct, and the dense point cloud generated from images is likely to have holes. In those cases, the point cloud generated from depth maps can be used to fill the holes.

Dense_compare_ex.jpg

Dense point cloud from images. Note the holes in the concrete as well as the plastic barrier.

Depth_compare_ex.jpg

Depth point cloud from LiDAR depth maps. Reflective and homogeneous surfaces are reconstructed.

Fused_compare_ex.jpg

Fused dense and depth point clouds. Holes in the concrete and plastic barrier are filled.

What is the accuracy of the reconstruction?

The absolute geolocation accuracy depends on how you georeference the images and if GCPs are used in the project or not.

  • With the integrated (phone) GNSS sensor, the absolute accuracy is expected to be a few meters.
  • With the viDoc RTK Rover, the absolute accuracy can be in the range of a few centimeters. For more information: How to use PIX4Dcatch with viDoc RTK rover.
  • When GCPs are used, the absolute accuracy is expected to be in the range of the GCP errors.

Research has revealed that it is possible to achieve 3D models with an absolute geolocation accuracy of less than 5 cm. For more information, see the white paper.

The relative accuracy of the reconstruction is expected to be in the range of 1 - 3 times the Ground Sampling Distance (GSD). More in the What is the relative and absolute accuracy of mapping article.

How can I get RTK geotags on mobile images?

You need to download the PIX4Dcatch app and purchase the viDoc RTK rover.

Since the RTK corrections are transferred via an NTRIP service, you will need a subscription to an NTRIP service corresponding to your location.

When connecting the PIX4Dcatch app to the viDoc RTK rover via Bluetooth, the images are automatically geotagged with the accurate positions from the viDoc RTK rover.

For more information: How to use PIX4Dcatch with viDoc RTK rover.

How can I purchase the viDoc RTK Rover?

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

Can I include GCPs in my PIX4Dcatch project?

GCPs can be integrated into your PIX4Dcatch project by exporting the images and processing them in PIX4Dmapper or PIX4Dcloud with your GCPs. More information on How to include GCPs into a PIX4Dcatch project.

How can I merge drone images with my PIX4Dcatch dataset?

It is possible to combine PIX4Dcatch terrestrial image data and aerial drone data in PIX4Dmatic and/or PIX4Dmapper. Acquire projects with sufficient overlap between them, using Manual Tie Points to merge the two projects together. It is advised to keep the ground sampling distances (GSDs) as close as possible. Wide variations between GSDs can hinder projects from merging together.

For more information: How to merge projects.

How to enable the Compass Calibration service?

To get a more accurate orientation in PIX4Dcatch on iOS, the Compass Calibration must be enabled:

  • Click on the Settings icon.
  • Select Privacy.
  • Select Location Services.
  • Select System Services.
  • Turn Compass Calibration ON.

Can I access the raw or native images directly in my app?

Any (logged-in) user can access and export images captured. Another way to access the images would be by using a PIX4Dcloud license. The images should be first uploaded to PIX4Dcloud and then downloaded.

Can I select the image resolution?

iOS Apple

With Apple iOS 16 installed, there is the ability to select the resolution when capturing PIX4Dcatch projects. The exact resolutions available will depend on each device. The current resolution will remain as the default selection. 

For more information: Settings - PIX4Dcatch

 
Important: Resource dependency will increase with the selection of higher resolutions including increased upload and process times and extra storage requirements.

Android

Due to limitations set by ARKit/ARCore, there is not the ability to select image resolutions. Should this change, PIX4Dcatch will adjust accordingly.

Can I directly upload images to PIX4Dcloud for processing using the app?

Yes. You can only upload the images to the cloud for processing if you have the PIX4Dcloud or PIX4Dcloud Advanced license or trial.

For more information: How to upload and process with PIX4Dcloud / PIX4Dcloud Advanced.

Can I export images from the app?

Every user with a Pix4D account can export images from the app. For more information: How to export PIX4Dcatch projects (iOS/Android).

Does the PIX4Dcatch process the 3D model directly on the mobile device?

No. To process an accurate 3D model, you would need a valid PIX4Dcloud, PIX4Dmatic, or PIX4Dmapper license or trial.

In which languages is PIX4Dcatch available?

PIX4Dcatch is available in the English and Japanese languages.

What is the cost of PIX4Dcatch?

PIX4Dcatch is a free application for capturing projects. A valid Pix4D account allows the free export of captured projects. However, a valid PIX4Dcloud license/trial is needed to upload the dataset to PIX4Dcloud, or a valid PIX4Dmatic or PIX4Dmapper license/trial to process locally after exporting.

For more information:

How can I get technical support for PIX4Dcatch?

For technical questions, Pix4D customers, and trial holders can contact our support team.

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

Where can I submit the product feedback and feature requests?

Please help us understand what you need most by sharing your use case and upvoting other users' feedback on the Pix4D Community.

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

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