Mixed Deck — All Certified Photogrammetrist Topics Flashcards

What causes 'layover' in radar imagery, and can it affect photogrammetric products?

Answer: In radar, layover occurs when tall objects lean toward the sensor; in photogrammetry, the analogue is relief displacement

Radar layover occurs when tall objects appear to lean toward the sensor due to the near-range compression of elevated objects; the photogrammetric analogue is relief displacement, where objects appear displaced from their true position.

Which laboratory calibration method uses precision optical collimators to simulate distant targets at infinity?

Answer: Goniometer calibration

Goniometer calibration uses a precision instrument with collimators to project parallel rays simulating targets at infinity, enabling measurement of angular relationships and lens distortion in a controlled lab environment.

Which term describes the interpretation of remotely sensed images to classify land cover?

Answer: Image classification

Image classification is the process of categorizing pixels in a remotely sensed image into different land cover or land use classes (e.g., forest, water, urban, agriculture). This is achieved by analyzing the spectral characteristics of pixels and assigning them to predefined categories, creating thematic maps that represent the distribution of various features on the Earth's surface.

What is the purpose of 'thinning' or 'decimating' a point cloud?

Answer: Reducing point cloud size by removing redundant points while preserving surface representation

Point cloud thinning/decimation reduces the number of points by removing redundant ones while preserving the essential shape and detail of the surface, making processing more manageable.

For USGS National Map Accuracy Standards, what horizontal accuracy is required for a 1:24,000-scale map?

Answer: ±12.2 meters (40 feet) at the 90% confidence level

USGS NMAS requires that 90% of well-defined points on a 1:24,000-scale map be within ±40 feet (±12.2 meters) of their true position.

What is the primary purpose of land surveying?

Answer: Measuring and mapping land positions and boundaries

The primary purpose of land surveying is to accurately determine and map the terrestrial or three-dimensional position of points, and the distances and angles between them. This is essential for establishing and defining property boundaries, planning and designing infrastructure, and creating precise maps for legal, engineering, and construction purposes.

What is 'image radiometric normalization' used for in digital photogrammetry?

Answer: Adjusting image brightness and color consistency across a mosaic to reduce seam visibility

Radiometric normalization adjusts brightness, contrast, and color across overlapping images to achieve visual consistency in the final orthophoto mosaic, reducing visible seams.

What is the main effect of a larger base-to-height (B/H) ratio in stereo acquisition?

Answer: Improved vertical (height) accuracy but potentially more occlusion

Wider intersection geometry improves height precision, though it increases viewing differences and occlusions.

In photogrammetric production, what is a 'calibration certificate' for a metric camera?

Answer: A laboratory report documenting the camera's interior orientation parameters (principal distance, principal point, lens distortion) determined by calibration

A calibration certificate documents the metric camera's interior orientation parameters—principal distance, principal point location, radial and decentering distortion—determined through laboratory calibration, essential for accurate photogrammetric processing.

In photogrammetric project specifications, what does 'NVA' stand for and how is it defined?

Answer: Non-Vegetated Accuracy — the vertical accuracy of the DEM in open, bare-earth areas, reported at the 95% confidence level

NVA (Non-Vegetated Vertical Accuracy) is the vertical accuracy of the DEM in open, non-vegetated areas assessed using check points, reported at the 95th percentile confidence level (≈ 1.9600 × RMSEz).

What is the approximate combined curvature and refraction correction for a horizontal sight of 1 km?

Answer: 0.067 m

The combined correction is about 0.0675 K^2 m, giving roughly 0.067 m at 1 km.

In image interpretation, 'texture' is best defined as what?

Answer: The frequency of tonal change within an area

Texture describes the fineness or coarseness produced by tonal variation too small to discern individually.

The strong near-infrared reflectance of healthy green leaves is primarily caused by what?

Answer: Internal scattering by the spongy mesophyll cell structure

Multiple scattering at cell wall–air interfaces in the spongy mesophyll produces high NIR reflectance.

What is spatial analysis primarily used for?

Answer: Examining spatial patterns and relationships

Spatial analysis is a set of techniques used to analyze data that has a geographic or spatial component. Its primary purpose is to uncover patterns, trends, and relationships that are not evident in non-spatial data, helping to understand phenomena across space. This involves using location, distance, and connectivity to derive meaningful insights.

What is 'vegetated vertical accuracy' (VVA) and why is it reported separately from NVA?

Answer: VVA is the 95th percentile absolute error in vegetated areas; it is reported separately because vegetation obscures the ground, causing higher and more variable errors

VVA is the 95th percentile absolute error in vegetated areas; it is reported separately because vegetation canopy obscures the ground surface, causing higher and less predictable errors than in open areas.

What does the ASPRS 2014 standard use instead of the traditional NMAS 90% circular error to define accuracy?

Answer: RMSE-based accuracy with separate thresholds for horizontal (RMSEx, RMSEy) and vertical (RMSEz) components

ASPRS 2014 replaced the circular error approach with RMSE-based accuracy metrics, separately specifying RMSEx, RMSEy, and RMSEz thresholds that are tied to the product's GSD or contour interval.

Regularly spaced rows of trees that identify an orchard are an example of which interpretation element?

Answer: Pattern

Pattern is the spatial arrangement of objects, such as the grid spacing of orchard trees.

What is 'map generalization' in the context of photogrammetric mapping?

Answer: The process of simplifying and selecting map features appropriate for the target map scale

Map generalization involves selecting, simplifying, and symbolizing features at a level of detail appropriate for the output map scale, since not all detail captured at the source GSD can be shown on a smaller-scale map.

What is 'ground sample distance' (GSD) in digital photogrammetry?

Answer: The real-world size represented by one pixel in the image

GSD (Ground Sample Distance) is the real-world dimension represented by a single pixel in the image, determining the spatial resolution of the final mapping products.

Which radar band offers the greatest penetration into forest canopy among these options?

Answer: L-band

Longer wavelengths like L-band (~23 cm) penetrate foliage further than shorter bands.