While photogrammetry and 3D scanning are both techniques of capturing three-dimensional data of physical objects, they are very different in terms of methodology and application. Photogrammetry involves the capture of multiple 2D photographs from various angles around the object or scene. These are then processed using software algorithms to produce a 3D model. A common application of photogrammetry includes aerial surveys for large areas like landscapes or archaeological sites, in which high-resolution cameras shoot hundreds of images that can be stitched together to form a 3D representation. Examples include Photogrammetry used in aerial mapping to depict vast areas, whereby drones can take thousands of images with which a high-resolution map is generated. This is where photogrammetry software sometimes can put together as many as 1,000 images into a model, with accuracy in the region of 1–2 cm, which makes it very efficient for large projects.
On the other hand, 3D scanning, such as with a device like the Revopoint POP 2, works by utilizing laser, structured light, or other means to scan an object for its geometry in three dimensions. A 3-D scanner is responsible for measuring depth, in addition to the object surface data, with its development converting it into a cloud of points while processing and output with quite high precision to attain information even on a micrometer scale. This applies as a very typical means with which a usual 3-d scanner operates on small size objects and other features inclusive of machinery parts at industrial sectors. For instance, alike the Revopoint POP 2 can have up to 0.1 mm precision, which is far more precise than what photogrammetry can achieve, considering it is for detailed scanning of small or complex objects.
A key difference between these two methods is the level of accuracy and resolution. 3D scanning generally has higher precision, especially with small or complex objects, and is perfect for reverse engineering or detailed inspections. Industrial design companies, for example, use 3d scanning to reverse-engineer parts that have very tight tolerances and can achieve an accuracy of millimeter or even sub-millimeter accuracy. By contrast, photogrammetry is better suited to larger-scale projects, capturing the full scale of a building or a terrain. While photogrammetry can produce highly detailed models, the resolution usually remains lower than what a 3d scanner can provide.
In terms of cost and time efficiency, photogrammetry can be more cost-effective for large areas, as it requires only cameras and software, while 3D scanning often requires expensive equipment, such as handheld or desktop scanners, which may raise the upfront costs. However, 3D scanning may save time in smaller projects due to its speed and precision in capturing data compared to the labor-intensive process of taking and processing hundreds of images in photogrammetry.
Photogrammetry prevails in a number of cases, especially in areas such as archaeology, where entire sites or artifacts are recorded from drones or ground-based cameras. The technique can be more cost-effective and faster for big mapping projects. On the other hand, 3D scanning is used in industries such as aerospace and automotive design when creating detailed and accurate models of parts, with precision required by high-performance standards.
In other words, though both ways are used for the construction of three-dimensional models, in projects which have larger coverage areas with lesser resources, photogrammetry is the best option, while 3D scanning offers extremely detailed, accurate models for industrial uses. In such cases, the application often depends on specific project needs related to either detail requirements or the size of an area or an object being captured.