How is Photogrammetry Used Today2023-12-12T14:52:25+00:00
Modern Day Use of Aerial Photogrammetry Technology
How is Photogrammetry Defined?
Photogrammetry Explained
The term photogrammetry can be dated back as far as 1867 when a Prussian architect called Albrecht Meydenbauer mentioned it in an article called “Die Photometrographie.” Photogrammetry is the term used when obtaining reliable measurement data about physical objects and their environment when interpreting photographic images from differing viewpoints. Photogrammetry uses the science behind stereoscopy where three-dimensional coordinates or points of an object can be determined by employing measurements taken from two or more photographic images taken from different positions. After these images are processed using sophisticated software, 2 dimensional image maps and 3 dimensional models can be created to a very accurate level of detail.
Today’s photogrammetric maps are created using sophisticated GIS software capable of producing surveyor-quality measurements of landscapes & infrastructure. These maps are sufficiently precise to give important insight into actual environmental conditions on the ground and are used in many applications such as determining quotative volumes, tracking erosion, plant density, and water clarity, among many other factors. That is only the tip of the iceberg in terms of what photogrammetry software is capable of providing.
Image triangulation is the process where at least two photos are taken from two separate places. Photographs created by using this method overlay and connect common pixels in the images to generate three-dimensional coordinates for the image subject.
Land surveying is known for its use of triangulation, but it is a popular concept utilised in many other areas, including construction, agricultural and of course military intelligence. Surveyors use equipment such as theodolites or ‘total base stations’ to triangulate locations to obtain precision positional information using the angles recorded relative to known coordinates from GPS systems, to create usable measurements. Triangulation networks, Real Time Kinematic and Post Processing Kinematic techniques create even more accurate survey grade precision using the GNSS.
Similar to how your eyes interpret objects and determine its depth or perceive depth, we have to see objects from various perspectives. Our two eyes view the image in front from two know view points, the left eye and the right eye, we then analyse the two pictures and, via stereopsis, assemble them into a single image we can understand.
Photogrammetry Essential Features
A photogrammetric map of model is only as good as its essential elements. The following capabilities are included:
Using common tied points, or coordinates that connect across several overlapping pictures, a direct connection between the images can be established. For this to happen easily, the majority of photographs must have common pixels in every shot. Aerial photography carried our by drones ensure this commonality by flying photographic missions in tight grids with significant photo overlap both to the sides and the front and back. With these common tie points, the overview mapped picture may be easily brought into alignment with the common coordinates and stitched together accordingly.
Further to this procedure, ground control points (GCPs) ensure further map accuracy by tying in explicitly known GPS coordinates on the Earth’s surface to the position of the camera in the air and the GPS reference of each pictures taken. Add to this software algorithms to element and compensate for lens distortions, field of view and sensor dimensions, the final two-dimensional map or three-dimensional model is create with significant precision.
What is RTK?
RTK stands for Real-Time Kinematic, a satellite navigation technique used to enhance the accuracy of GPS (Global Positioning System) positioning. It is a high-precision positioning method that provides real-time, centimeter-level accuracy for various applications. RTK works by using a fixed base station and a mobile rover receiver to improve the positioning accuracy by correcting the errors caused by atmospheric disturbances and satellite clock discrepancies.
The RTK system operates by measuring the phase difference between the carrier signals of GPS satellites received by the base station and the rover receiver. The base station precisely determines its location and calculates the errors in the GPS signals. These error corrections are then transmitted to the rover receiver in real-time. The rover receiver combines these corrections with its own GPS measurements to calculate its position with enhanced accuracy. This real-time correction capability makes RTK suitable for applications that require high precision positioning, such as land surveying, precision agriculture, construction, and autonomous vehicles.
One of the key advantages of RTK is its ability to provide centimeter-level accuracy in real-time, which is significantly higher than the standard GPS positioning accuracy of a few meters. This level of precision enables various industries to carry out tasks with greater efficiency and reliability. For example, land surveyors can accurately measure distances and angles between points, allowing for precise mapping and boundary determination. In precision agriculture, RTK can be used to guide farm machinery with centimeter-level accuracy, optimizing the application of fertilizers, pesticides, and irrigation. Overall, RTK technology plays a crucial role in improving the accuracy and reliability of GPS positioning, benefiting a wide range of industries and applications.
What is PPK?
PPK, which stands for Post Process Kinematic, is a technique used in surveying and geodesy to improve the accuracy of GPS data. It is commonly used in applications such as aerial mapping, precision agriculture, and land surveying. PPK involves processing raw GPS data collected by a receiver after the data has been collected in the field. This allows for the correction of errors and improves the accuracy of the position data.
The PPK technique involves combining the raw GPS data collected in the field with additional data collected from a base station that is set up at a known location. The base station data provides precise timing and positioning information, which is used to correct any errors in the GPS data collected by the receiver. By comparing the data from the base station with the data collected by the receiver, PPK algorithms can calculate the accurate position and timing information.
One of the major advantages of PPK is that it allows for greater flexibility in data collection. Since the processing is done after the data has been collected, it is possible to collect data using a single receiver and process it later using PPK techniques. This eliminates the need for real-time communication between the receiver and the base station, which can be challenging in remote or difficult-to-reach locations. Additionally, PPK can significantly improve the accuracy of GPS data, making it a valuable tool for applications that require high precision measurements.
Photogrammetry in Commercial Applications
The many uses of photogrammetry
The use of photogrammetry is diverse, from simple orthomosaics, digital terrain and surface terrain models to specialist 3D models, NDVI (Normalized Difference Vegetation Index) and thermograms, photogrammetry covers a very full spectrum of commercial applications.
An orthomosaic is a birds-eye perspective of surface topography, where the resulting stitched picture has been accurately reproduced from multiple smaller pictures.
Digital Surface Models (DSM) is an elevation model that captures both the environment’s natural and artificial features. It includes the tops of buildings, trees, powerlines, and any other objects. Commonly, this is seen as a canopy model and only ‘see’s ground where there is nothing else above it.
A Digital Terrain Model (DTM) is a bare-earth elevation model. DTMs do not contain any features above the bare-earth, even persistent ones. Thus, they can be paired with DSMs to derive height information regarding objects on the surface.
A Digital Elevation Model (DEM) is a generic term for an elevation model, which encapsulates both DSMs and DTMs, and can be generated from various methods, often, because of scale and environment, differentiation between DSM and DTM is unnecessary.
Due to is accuracy and efficiency, aerial photography conduct by drones are the most frequent use of photogrammetry. It has simplified the search for environmental data and offers an extraordinary amount of information about a particular location or object.
Surveying of Land
Photogrammetry is utilised in civil surveying and kind yields quick, accurate and efficient results. The application benefits many organisations, including construction teams, governments, building planners, and architects. Through photogrammetry, they get an understanding of the possible outcomes of their project as well as needed safety precautions, along with the quantity evaluation of aggregates and materials.
Engineering
The field of engineering is aided by drone photography when it comes to construction site evaluation and visualisation and when creating perspective pictures and 3D models. Engineers may produce images of project outcomes, as well as examine what the current environment is right now.
Domestic Property
For almost 80% of millennials, their current or future homes can now be found in digital format on mobile devices. This means mobile-friendly, informative property listings which positively impact the purchasing process and their comprehension of the purchase during the marketing and sales process. Viewers receive an overview of the house, seeing it from all sides along with how the property relates to its environment.
Entertainment and film
In movies and video games, photogrammetry plays a large part in set design and artificial world-building. Once an environment is 3D-modeled, it enables designers to bring unique things to life in a virtual environment, such as whole cities for action scenes and historically correct components, such as sculptures and buildings. Some well-known franchises that employ photogrammetry include “Battlefield” games, which use the aesthetics of their 3D renders and recreations to integrate nicely with their game assets.
Military intelligence
The military have been using photogrammetry to collect covert data for along time, since at least the 2nd Word War. In order to comprehend a given terrain on the battlefield, accurate geo-locational models that process data quickly are required. 3D maps are created using aerial images and photogrammetric technologies with no human involvement and without the enemy knowing. Information about troop and tank/vehicle movements can be determined from using photogrammetry analysis of imprints in earth and sand when compared over time to provide a comprehensive understanding of military activity, along with the construction and deconstruction of military facilities, command bunkers and missile silos.
Forensics
An important portion of criminal investigation is also now accomplished via photogrammetry. It may be valuable to collect facts about the crime scene, such as identifying what happened and ascertaining whether it was physically feasible. Photogrammetric specialists are also often used in looking at road traffic accidents and the data collected subsequently used in the courts.
Sports
The more that coaches and researchers learn about athletes’ actions, the better their tactical decisions will be. Virtual training systems and the monitoring of physical exertion levels provide valuable data about the exercise used by sports mena and women. We see the principles of photogrammetry used in professional football each week with the dread VAR (Video Assistant Referee) used to determine if a play is off-side! Hikers, climbers, skiers, and snowboarders also find topographical maps useful for their outdoor activities. Using photogrammetry to map locations that are far away is more straightforward.
Agriculture and Forestry
Aerial photographs of farmland can provide an understanding of soil conditions, irrigation schedules, nutritional status, and pests. This gives farmers an idea of when to sow or when to irrigate and fertilise their crops. They may also use photogrammetry to evaluate crop damage and growth following natural disasters such as floods or storms. Using photogrammetry in this way makes researching and maintaining forests considerably simpler. These models may be used to quantify different characteristics of a forest, including volume and height, in order to learn more about how a forest develops.
We are certified and approved drone pilots and work throughout the UK to provide survey grade aerial photography inspection surveys, photogrammetry surveys, 2D orthomosaic, 3D modelling and mapping as well as video/filming and thermography services. Fully insured and certified by the CAA with enhanced permissions for day and night time flights.
