Combining LiDAR x Photogrammetry

LiDAR

LiDAR (Light Detection and Ranging) uses laser pulses from a scanner to measure distances to surfaces. It captures precise 3D information about the shape and features of the terrain and objects by measuring the time it takes for the laser pulses to return. This allows for highly accurate mapping of the environment’s structure and details in three dimensions.

However, LiDAR requires a direct line of sight between the scanner and the target, so obstacles like buildings, trees, or terrain can block or reduce the amount of information captured. Additionally, LiDAR does not capture good color or texture information, meaning the resulting data lacks the visual detail that photos provide.

Photogrammetry

Photogrammetry uses overlapping photos taken from the camera to create 3D models. It works by analysing the images to find common points and reconstruct the shape and position of objects. It provides rich detail and texture to the object.

Photogrammetry can be less accurate when capturing larger 3D terrains, especially in complex or vegetated areas. Processing large sets of high-resolution images can be very time-consuming.

Why we combine LiDAR x Photogrammetry

Combining LiDAR and photogrammetry leverages the strengths of both: LiDAR provides highly accurate 3D measurements and structural data, while photogrammetry adds detailed color and texture from photos.

How Does it work?

Reality Capture aligns images to LiDAR data by finding Shared features between them. First, it analyzes the photos to detect points or details that appear in multiple images and uses those to build a 3D model.

To align the sparse point cloud and LiDAR data, Reality Capture looks for matching shapes or details in both the images and the LiDAR scan—like edges, corners, or surfaces. Reality Capture can only line up the two data set if there are enough overlap between the photos and the scanned area, so be considerate of overlaps when capturing data.

Planning

It's recommended to capture all the wanted data of the same environment at the same time, to avoid the environment and its lighting condition to change. to achieve this and save the time need it on site, its important to plan for your scan ahead.

1. RELi

Routing, Environment, Limitations.

Routing refers to your intended route to adequately capture your data so that it is efficient and will result in a complete scan.

Environment refers to dealing with any environmental variables, such as lighting, crowds etc.

Limitations refers to dealing with limitations in the technology's scanning process, such as dealing with transparent objects.

1. How much you want to capture?

Define the size of the area you intend to capture. Based on this, determine how many LiDAR scans will be required to cover the entire space with sufficient overlap and detail.

1. What do you want to capture in detail?

Understanding which elements or features are important to capture in your project helps determine the locations for taking photographs, ensuring that areas requiring more detail and texture are effectively documented.

Post-Processing Captured Data

Photogrammetry Introduction

This tutorial explains the process of creating a 3D model in Reality Capture using photos. It covers the basic photogrammetry method.

Introduction to Combining Laser Scan + Images in Reality Capture

This video will guide you through aligning photo datasets with LiDAR scan data.

• Please note. this video demonstrates with drone data. When import Lidar scan data, switch the importing data type to terrestrial.