By Emily Zawacki
Lidar (light detection and ranging) is a common remote sensing technique used to create high-resolution three-dimensional models of landscapes and built features. Lidar uses laser pulses to measure distances to the ground or other features. Traditionally, lidar scanners are mounted to airborne or terrestrial platforms, but we now have the power of lidar in our own hands.
Apple’s latest products, the iPhone 12 Pro and Pro Max, iPhone 13 Pro and Pro Max, and iPad Pro now feature a built-in lidar scanner that can create 3D representations of close-range objects (up to 5 m away).
The built-in lidar scanners on the new iPhone and iPad Pros provide an easy, hand-held way to rapidly create 3D models of objects of interest. The 3D model is generated by combining lidar and photogrammetry (pictures taken from different views of the object to create a 3D reconstruction), where the lidar provides a known scale and the photos provide texture for the 3D models. This feature on iPhones/iPads holds particular utility in the geosciences for easily creating 3D scans of features such as cliff faces, rocks, and paleontological samples. Luetzenburg et al. (2021) tested the application of iPhone 12 Pro lidar with coastal cliffs, with results showing good promise for geoscience applications.
There are several freely available applications for download on the Apple App Store (e.g. 3D Scanner App, Polycam, etc.) that use the iPhone/iPad lidar sensor along with the device’s cameras to create a 3D model of objects.
To demonstrate the iPhone lidar and photogrammetry capabilities and potential applications in the geosciences, we will create a 3D scan of the rock shown below using the “3D Scanner App” application for the iPhone, using an iPhone 13 Pro.
The user initiates the scan and begins by moving the device around the full extent of the object. The preview within the app shows a textured mesh overlay of the scanned area (image below). Areas that are in dotted green without a mesh texture still need to be scanned to be included in the 3D output.
Once the user has sufficiently scanned and covered the full extent of the object of interest, the application outputs a rough texture map. The user can then choose to process the scan with high-definition texture and detail. The processing of the rock scan in this instance took approximately one minute.
This scan captured a total of 244 images. The app also allows you to directly take measurements of objects on the scan.
From the app, the scan can be exported into several file formats including a LAS formatted point cloud. These files can then be opened in any 3D point cloud processing software such as the open source CloudCompare.
Scanning provided a clean output, even with harsh sun and shadows. We have found that results are better when scanning solid-surface features like rocks, rather than vegetation which results in less detail being captured. Creating scans are extremely easy and quick to acquire. Attaching an iPhone to a selfie stick can easily extend the range of the scan.
While the iPhone 13 Pro remains quite expensive ($1,000+ at the time of this writing), it still provides a relatively cost-effective alternative to other remote sensing devices. iPhone/iPad lidar offers geologists a quick and convenient hand-held way to collect close-range 3D scans that require little to no pre-planning while in the field. Additionally, there is significant potential to develop classroom or teaching exercises using the lidar capabilities in these devices, where students can capture their own 3D scans. The iPhone lidar capabilities also serves well for hobby applications, as people can easily create 3D scans of rock collections, or can use the scanner to create 3D models which can then be 3D printed.