JNTU B.Tech III GEOINFORMATICS Previous Question Paper (February/March - 2022 - R16)

Stereoscopic parallax is the apparent displacement of the position of an object with respect to a reference point or system caused by a change in the observer's position. In aerial photography, it is the change in the position of an image of an object from one photograph to the next due to the aircraft's motion between exposures.

Key characteristics include:

• Measurement: Parallax is measured as the difference in the distance between two corresponding points on successive overlapping photographs.
• Verticality: Parallax is strictly horizontal and parallel to the line of flight.
• Height Determination: The magnitude of parallax is directly proportional to the height of the object above a reference datum. This relationship is expressed by the formula:
  h = (H × dp) / (P + dp)
  where h is the object height, H is the flying height above the datum, dp is the differential parallax, and P is the absolute stereoscopic parallax at the base of the object.

This phenomenon is the fundamental basis for stereoscopic vision and the extraction of 3D topographic data from 2D aerial images.

Aerial photo-interpretation is the act of examining photographic images for the purpose of identifying objects and judging their significance. The fundamental principles rely on the systematic analysis of image characteristics, often referred to as the elements of interpretation:

• Tone/Color: The relative brightness or color of objects, which is often the primary indicator for identification.
• Size and Shape: The physical dimensions and geometric form of objects, which help distinguish between man-made and natural features.
• Texture and Pattern: The frequency of tonal change and the spatial arrangement of features, which assist in identifying land cover types like forests or urban grids.
• Shadow and Association: Shadows provide profile information, while association helps identify objects based on their proximity to other known features.

The primary objectives of aerial photo-interpretation are to:

• Extract qualitative and quantitative information about the Earth's surface.
• Facilitate land use and land cover mapping.
• Support resource management, including forestry, agriculture, and geological surveys.
• Provide essential data for environmental monitoring and infrastructure planning.