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- [Instructor] There are many types of photogrammetry.

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And after watching this video, you'll be able to distinguish

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between several different approaches

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including the one we'll use in this course.

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In a literal sense, photogrammetry means

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extracting measurements from photographic images.

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The original definition is tied to uses

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in surveying and mapping.

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We can see an example of an early photogrammetry technique

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in the image on the left

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where a grid called a perspectometer

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is superimposed over the image.

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This was helpful in producing topographic maps

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of landscape features.

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Advancements in mathematics, optical sensing,

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and computer hardware and software

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have allowed for many variations

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on these basic measuring techniques.

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This includes highly accurate

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three-dimensional measurements of objects,

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such as the computer tomography or CT scan

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in the center image.

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This type of photogrammetry combines x-ray images

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into three dimensional representations

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of internal body structures.

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Another example of a photogrammetry technique

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can be seen in the image on the right,

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which is a 3D representation of a landscape

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made using LIDAR, a technology that combines lasers

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and other sensor data to make high resolution models

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of landscapes, buildings, archeological sites,

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and other relatively large objects.

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This course is focused on reconstructing

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accurate 3D models and textures

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from photographs of relatively small scale objects.

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Here, you can see an example

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of a 3D reconstruction of a bird figurine

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constructed from about 30 individual photographs

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represented by the blue rectangles.

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When we use the word photogrammetry in this course

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we'll be referring specifically to this sort of approach.

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But just know for future reference

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that there are many fascinating variations

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on our process that still count as photogrammetry.