3rd October 2023 - Photogrammetry
Definitions:
What is photogrammetry-
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images
Radiometry
how light reflects off things. heat maps. radio waves. predator.
•Radiometry is a method for analysing electromagnetic radiation. It is a way to measure how light interacts with different objects, including wavelengths of energy that are not visible to the human eye.
•Whenever you look at an object, you see light of specific colors reflected back at you. There are more colors than you can see - we only perceive what our eyes can detect. For example, when you look at plants, you’re usually going to see a predominance of green. Green light is reflected by plants because they do not use it when they absorb energy from the sun. With radiometry, you can measure how plants reflect that light
Triangulation
gps view. lots of different views make up a picture (example our eyes, ignoring the nose)
CREATE point cloud?
•The photos collected for photogrammetry are 2D, and for many outputs - like digital surface models or point clouds - we need to convert that data to be usable in 3D. Triangulation is the technique for creating 3D point measurements.
•Triangulation is also used by our eyes. The idea is that images taken from different locations can be used to create a 3D model by comparing the differences between them.
RTK & PPK - gps
real time kinematic (speaks to location)
post processing kinematic (doesnt speak to the location)
•RTK (real-time kinematic)
•PPK (post-processing kinematic)
•methods for measuring and recording geolocational data. They are both GPS correction technologies that collect location data, identify errors, and make corrections either during or after surveying.
Tie Points
tracking points, uses a point that has similarities with another point, a common point to share to create a picture.
•A tie point is a point that is common to several images that can be used to connect them. They are anchor points - a location where the geographic position is absolute. There are several names for tie points (e.g. Ground Control Points or check points).
Methods of Capture:
Lidar - less detailed. polycam app.
•LiDAR is a remote sensing method. LiDAR technology uses the light from a laser to collect measurements. These are used to create 3D models and maps of objects and environments.
•Light Detection and Ranging. The acronym LiDAR is often used to name this remote sensing method. It uses light to measure distances and is also known as laser scanning or 3D scanning.
LIDAR stands for Light Detection and Ranging. It is a remote sensing technology that uses laser light to measure distances and create highly accurate 3D maps or models of the environment. Lidar systems are commonly used in a wide range of applications including, surveying, cartography, auto vehicles, forestry, archaeology and geology.
LIDAR works by emitting rapid and short laser pulses of light. These laser pulses bounce off objects or surfaces and reflect back to the LIDAR sensor. The sensor records the precise time it takes for the laser to return.
The LIDAR system uses the speed of light and the time it took to return to calculate the distance between the sensor and the surface, known as a range measurement. The sensor collects data from a range of angles and is stored in a collection called a point cloud. The point cloud can be processed to create 3D models of the subject.
Lidar can be used in self-driving cars, drone based mapping and environmental monitoring. It helps us to understand the physical world and create innovative solutions.
Photogrammetry
overlapping photos of the object, structure or space. converts to 2D or 3D model. Uses DSLR equipment,
Photogrammetry is a technique used to measure and map objects and landscapes using photographs. It involves extracting geometric information, like distances, angles, coordinates from 2D images. This information is used to create accurate 3D models, maps and measurements.
Photogrammetry works by analysing the perspective differences in multiple images of the same subject, taken from different viewpoints or angles. It then reconstructs the subject’s precise and detailed 3D shape as a model.
•Photogrammetry is the art and science of extracting 3D information from photographs. The process involves taking overlapping photographs of an object, structure or space and converting them into 2D or 3D digital models.
•This is commonly done with high res DSLR Camera equipment or specialist image sensors
Video Frames
uses video to convert to 3D, must be high quality video. extracts the frames to create the scene.
•Like Photogrammetry, it is common to extract individual frames from video to process as photogrammetry
•Certain rules such as High refresh rate and limited motion blur must be implemented for a clean result!
Interesting uses:
Backup Ukraine (polycam) free for Ukraine to use.
invites people to scan all of Ukraine archiving it affected by the war. the damaged that was caused. renders on polycam servers not the app and gives back a .fpx file.
sniper elite 5
Ghost town capture. mines and landscape. drone footage used. 60fps. entire cave system.
Reality Capture
best quality 250-500 images
the photos need to be of all angles possible, and lights possible,
inputs - find - extract - select all images (139)
alignment - align images - wait - workflow - start button.
software optimising processing - can adjust small bits like colour and fill in holes in the software.
Fire Exit Example
132 Photographs
3D scene screenshots
Our Pipe explanation
photo example
screenshots of 3d scene:
bolt photos
bolt 3d screenshots
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