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Photogrammetry in Point Cloud

Published August 24, 2021
ScanX Photogrammetry Point Cloud

The generation of Point Cloud data is not only limited to LiDAR. Another helpful technology called photogrammetry also assists different industries in creating 3D models (Data source: Example of photogrammetry inaccuracies DJI P4 RTK).

In this article, we will look at how photogrammetry is being used in point cloud data.

 

What is Photogrammetry

ScanX Camera
Photogrammetry is defined the process of procuring information about a subject concerning its environment. It comes three words, photo meaning light, gram meaning recording, and metry meaning measurement.

When combined, it is also known as the measurement of light recordings in the form of images.

Historically, photogrammetry used to create maps of different locations. Modern photogrammetry has led experts to render 3D information just by gauging distances available in 2D pictures.

ScanX Maps
tackWith the help of this technology, surveyors generate depth for mere flat photographs. Thus, the end result is a stereoscopic 3D representation of an area.

Branches

Photogrammetry mainly uses the science of geometry and optics to obtain data. Metric and interpretative branches divide it into two.

Metric tackles accurate and precise computations regarding the x, y, and z coordinates of a subject. On the other hand, interpretative touches classification and identification of different attributes seen in the photo.

ScanX Branches of Photogrammetry
Both metric and interpretative photogrammetry benefits point cloud data generation, as accurate measurements and object segmentation are necessary.

Methodology

Three things are necessary to start photogrammetry: a camera, a measurement tool, and result storage. The camera is for the capture of multiple images, the measurement is to compare the distances of the photos, and the result storage acts as the medium that deposits observations.

ScanX Parts of Photogrammetry Device

Photogrammetry uses multiple camera views to gauge slight or major differences in measurements. With the help of multiple perspectives, it results to an exact 3D representations.

The same process happens in the human eye. As humans have two different sources of information, we grasp depth, distance, and spatial coordinates.

Since computers are not limited to only two images, they gather and render more precise and accurate data.

Types of Photogrammetry in Point Cloud

Two types of photogrammetry exist, and these are terrestrial and aerial.

When a camera is handheld or attached to a tripod and then used to gain measurements inland. It uses ground-based photographs for recording.

ScanX Types of Photogrammetry

On the other hand, cameras attached to vehicles capable of flight such as UAVs, hot air balloons, or drones identify as aerial photogrammetry tools.

ScanX Drone UAV
Both types are applicable in point cloud data generation. However, it should be noted that aerial data gathering is faster while terrestrial is slower but more precise.

Processing

To greatly benefit from the point cloud measurements taken from a photogrammetry process, post-processing is necessary.

Platforms that allow classification of objects, conversion to 3D models enable this to happen, including clean-up of noise in each data set.

While traditional processing software is widely used for these tasks, they present many limitations. First, they require heavy-duty workspaces to accommodate the rendering process. Another is that licenses for these platforms usually cost thousands of dollars.

ScanX Construction Management

Datasource: Device, Topcon GLS2000

ScanX, a web-based point cloud post-processing software, removes these cons. It is an easy-to-use, intuitive, and collaborative system full of automated workflows.

 

Photogrammetry vs. LiDAR in Point Cloud

One major advantage of LiDAR with photogrammetry is its core concept. While LiDAR relies on lasers generated by a scanner, photogrammetry has no inherent light source and only bases on captured images.

Another is that LiDAR can penetrate between gaps of different objects such as vegetation. This enables better surveying in cases where many leaves or trees are present.

In terms of color accuracy, photogrammetry is superior since it makes use of already captured photos to generate digital twins. This is not present in LiDAR since it uses laser bits to get an overall sense of an area. Thus, photorealism is possible when dealing with photogrammetry.

Another major difference is that LiDAR has a faster processing speed, and its measurements are less taxing to compute since timing systems, GPS, and IMUs are already embedded.

ScanX Stockpile Ore Management
Nevertheless, both photogrammetry and LiDAR are still widely used in point cloud data creation. Some industries even combine these two tools to compensate for color accuracy and processing times.

 

Applications

Disaster Management

ScanX Point Cloud Disaster Management
Aerial photogrammetry has great usage in disaster response. With data taken from calamity-hit areas, it processes the amount and volume of debris for better search and rescue.

Above is a laser scan taken at the onset of a mudslide disaster in Atami City, Shizuoka that was post-processed with ScanX. With the swiftness and accuracy of our platform, concerned Japanese organizations, as well as the government, quickly responded to address issues. Not only that but the total damages was also estimated.

 

Area Mapping

ScanX Area Mapping
Photogrammetry is very beneficial for surveyors, civil engineers, and geodetic engineers as they can get accurate data of an environment even if they are not on-site. As a contactless technology, human presence is not necessary to complete a data capture process.

Military Industries

ScanX Military Applications
Photogrammetry enables the safe execution of missions for military personnel. It tracks locations, determine the best paths, and gauge distances between different subjects in the field.

Mining

ScanX Mining Photogrammetry
Mining benefits from photogrammetry as obtained point cloud data calculates volumes of stockpiles and minerals in a specific zone. It can also remove common workplace hazards through virtual and digital inspections.

Forestry

ScanX Forestry

Datasource: SLAM Emesent capture with terrestrial scan (www.emesent.com)

Softwares gather total area and canopy sizes with processed point clouds from photogrammetry. Powerful tools such as ScanX can even segment trees separately to count them or determine their respective trunk size, tree height, and even diameter.

Best Photogrammetry Point Cloud Processor

ScanX is an amazing web-based platform that uses advanced algorithms to process point clouds taken from photogrammetry. It features an intuitive and easy-to-learn platform that encourages collaboration.

Web-Based, High-Accuracy Point Cloud Processing.
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