LiDAR and RealityKit – Capture a Real World Texture for a Scanned Model

Object Reconstruction

10 October 2023, Apple released iOS Reality Composer 1.6 app that is capable of capturing a real world model’s mesh with texture in realtime using the LiDAR scanning process. But at the moment there’s still no native programmatic API for that (but we are all looking forward to it).

Also, there’s a methodology that allows developers to create textured models from series of shots.

Photogrammetry

Object Capture API, announced at WWDC 2021, provides developers with the long-awaited photogrammetry tool. At the output we get USDZ model with UV-mapped hi-rez texture. To implement Object Capture API you need macOS 12+ and Xcode 13+.

To create a USDZ model from a series of shots, submit all taken images to RealityKit’s PhotogrammetrySession.

Here’s a code snippet that spills a light on this process:

import RealityKit
import Combine

let pathToImages = URL(fileURLWithPath: "/path/to/my/images/")

let url = URL(fileURLWithPath: "model.usdz")

var request = PhotogrammetrySession.Request.modelFile(url: url, 
                                                   detail: .medium)

var configuration = PhotogrammetrySession.Configuration()
configuration.sampleOverlap = .normal
configuration.sampleOrdering = .unordered
configuration.featureSensitivity = .normal
configuration.isObjectMaskingEnabled = false

guard let session = try PhotogrammetrySession(input: pathToImages, 
                                      configuration: configuration)
else { return 
} 

var subscriptions = Set<AnyCancellable>()

session.output.receive(on: DispatchQueue.global())
              .sink(receiveCompletion: { _ in
                  // errors
              }, receiveValue: { _ in
                  // output
              }) 
              .store(in: &subscriptions)

session.process(requests: [request])

You can reconstruct USD and OBJ models with their corresponding UV-mapped textures.