Photogrammetry Exam 1

photogrammetry

the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring, and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena.

When did photogrammetry first occur?

350 BC- Aristotle projecting images

Who is the “Father of Photogrammetry”?

Colonel Aime Laussedat

What are the four forms of photogrammetry?

terrestrial, aerial, metric, interpretative

Vertical photos

are photographs taken directly above the subject, providing a true vertical perspective (NADIR)

Low oblique photos

are photographs taken at an angle to the subject, capturing a view that includes both the ground and the horizon.

High oblique photos

are photographs taken at an angle above the subject, showing the ground as well as a significant portion of the sky.

Spatial Resolution

pixel size that determines the clarity of an image. goes down as I fly higher

Temporal resolution

the frequency at which images are captured over time, affecting the ability to monitor changes in a scene. how often the scene is imaged

Spectral resolution

the ability to distinguish different wavelengths of light in an image, which affects the detail and quality of the information captured. color bandwidth

Radiometric resolution

the ability of a sensor to detect and represent variations in the intensity of light, impacting the detail of the image. comes in bits, separates into bins by the amount of light

Spherical aberration

Rays that pass through the edge of the lens do not focus the same as rays that pass through near the center of the lens

Chromatic aberration

different colors focus at different spots

Astigmatism

The lens does not focus light symmetrically the same resulting in multiple focal points

Defocus

image forms in front of/behind sensor; more blurry at edges or looking at the wrong thing

Coma

Occurs when incident light is not perpendicular to the optical axis

Field curvature aberration

occurs when a focal plane is not planar but on a curved image surface

Distortion

a type of optical aberration that causes straight lines to appear curved or warped in an image, often due to lens imperfections.

Barrel distortion

a type of distortion where straight lines near the edges of an image bow outward, making the image appear wider in the center.

Pincushion distortion

a type of distortion where image edges are pinched inward, causing straight lines to bow outward, typically seen in telephoto lenses.

Index of refraction

a measure of how much light bends when it enters a medium, defined as the ratio of the speed of light in a vacuum to the speed of light in the medium. variation leads to chromatic aberration

Snell’s Law

describes the relationship between the angles of incidence and refraction when light passes between two different media, stating that the ratio of the sines of these angles is constant and proportional to the indices of refraction of the two media.

Dispersion

the phenomenon where light separates into its component colors when passing through a prism or medium, due to varying indices of refraction for different wavelengths.

scale

the ratio of the photo distance to the ground distance

relief displacement

shift in photographic position of an image caused by the object being above or below the datum

Parallax

change in relative position of objects in photo versus objects in real life