How Photogrammetry Brings Real-World Visuals to VR

Introduction

Virtual reality (VR) allows us to experience immersive digital worlds. To make these worlds feel real, we need realistic visuals. Photogrammetry is a crucial technique for capturing detailed 3D models from the real world to use in VR. In this article, I will explain what photogrammetry is, how it works, and why it’s important for creating compelling virtual environments.

What is Photogrammetry?

Photogrammetry is the process of generating 3D models from 2D photographic images. It involves taking multiple photos of an object or environment from different angles. Software then analyzes these photos to calculate the exact 3D structure and texture of the subject.

The output is a detailed 3D mesh that recreates the original object or scene with photo-realistic textures applied. Unlike 3D models created solely in modeling software, photogrammetric models retain precise, real-world visual detail down to small cracks and imperfections.

How Does Photogrammetry Work?

The photogrammetry process consists of three key stages:

1. Image Capture

The first step is to systematically photograph the subject from multiple angles. Typically, 50-100+ images are required to capture details from all perspectives. Images should surround the subject at different heights, distances, and rotation angles. Overlapping photos from several viewpoints are necessary for the software to recognize matching points.

2. Image Processing

Photogrammetry software analyzes the image sequences, identifies matching features across photos, and triangulates their 3D positions. Sophisticated computer vision algorithms detect hundreds of thousands of common points on the subject across multiple images.

By pinpointing the exact pixel coordinates of these matched points from different camera angles, the software can calculate the precise 3D location of these points in space.

3. 3D Model Generation

Once the matching points are triangulated into a sparse 3D point cloud, the software generates a polygonal mesh by connecting these points based on the camera positions. Photographic textures are also extracted and applied onto the 3D geometry.

The final output is a high-fidelity 3D model with detailed shape, scale, and realistic surface textures. The model can then be exported for use in VR/AR applications.

Why is Photogrammetry Important for VR?

Photogrammetry enables the creation of realistic 3D assets that bring the real world into virtual environments. Here are some key reasons it’s a vital VR technique:

• Realism – Photogrammetric models have genuine real-world textures and details not achievable with manual 3D modeling. This level of visual authenticity is crucial for immersive VR.

• Efficiency – Photogrammetry is much faster than meticulously recreating 3D models and textures by hand. It allows rapid conversion of real objects into digital assets.

• Accessibility – Photogrammetry democratizes 3D content creation by enabling anyone to generate detailed 3D assets from simple photographic images. No 3D modeling expertise is required.

• Preservation – Photogrammetry can digitally preserve real objects, environments, and cultural heritage sites in realistic 3D. These assets can then be experienced in VR.

Photogrammetry for VR Workflow

Here is a typical photogrammetry-to-VR pipeline:

1. Capture 50+ photos of object/scene from all angles
2. Process images in photogrammetry software (e.g. RealityCapture, Metashape)
3. Export 3D model & textures
4. Optimize 3D assets for real-time VR rendering
5. Import assets into VR engine (e.g. Unity, Unreal)
6. Program VR interactivity and navigation
7. Build & deploy VR application

The photogrammetric 3D model provides the realistic visual foundation. VR development tools then enable first-person interactive experiences within the captured space.

Challenges of Photogrammetry

While offering many benefits, photogrammetry also comes with some technical challenges:

• Requires extensive image capture covering all angles

• Computationally intensive processing that demands significant GPU power

• Manual cleanup of 3D models may be needed to fix artifacts

• Capturing textures of reflective or translucent objects can be difficult

• Large high-fidelity models require optimization for real-time VR

• Lighting conditions must remain consistent across all photos

Photogrammetry Use Cases

Photogrammetry has enabled impressive VR experiences across diverse applications:

• Virtual tourism – Real-world landmarks and locations converted into explorable VR environments, like photogrammetric 3D tours of museums or historic sites.

• Digital twin creation – Manufacturing facilities, factories, or architectural spaces replicated in VR via photogrammetry for remote collaboration, design review, and virtual training.

• Game development – Photogrammetric scans of objects like furniture and props used to quickly populate detailed game environments.

• Cultural heritage – Digitally preserving heritage artifacts and sites like monuments and statues in 3D for education and posterity.

• Volumetric video – Capturing moving humans via multi-camera photogrammetric scanning to generate interactive holograms for VR.

The Future of Photogrammetry

Photogrammetry will only increase in importance as consumer VR strives for greater realism. Ongoing advances in photogrammetry software, computing power, and 3D sensors enable higher model fidelity and faster capture. Machine learning techniques may also help automate parts of the photogrammetry pipeline.

As creating realistic VR environments gets easier, photogrammetry provides the bridge to bring the physical world into exciting virtual worlds. The ability to digitize and experience frozen moments in time and space will transform how we interact with our world in virtual reality.