Map, Air Photo, and Satellite Interpretation

Geography 380

Spring, 1999

FINAL EXAM STUDY GUIDE

The final exam will be Tuesday, May 18, 8-9:50 a.m. It will consist of 10 short answer questions and one or two interpretation exercises. (I haven't decided precisely what these will consist of yet.) Approximately 50% of the exam will be comprehensive, including more general questions on material from the first two-thirds of the semester (map and air photo sections). The other 50% will focus on satellite imagery and image processing and interpretation.

Topics and concepts that may be covered:

Map Interpretation (general, as it relates to the whole course)

Map symbols -- point, line, area, numerical & relative
Map scales -- different types
Map projections -- in general
Coordinate systems -- appropriate uses
Survey systems -- history, uses
Topographic maps, thematic maps -- portrayal of information,uses
Project strategies -- how you use maps to compile information, answer questions

Air Photos (much of this overlaps with satellite imagery so will be covered in more detail)

Electromagnetic Spectrum
Near Ultraviolet, Visible, Infrared (near, mid, far), etc.
Reflected, scattered, absorbed solar radiation
Emissivity of different materials

Spectral reflectance of different materials
Films (skip structure) --black & white, color, infrared, appropriate uses

Stereoscopic viewing (be sure you can do set up and view properly)

Types and sources of distortion
Resolution, photo scale (uses of different, methods for calculating)
Land Use Mapping, Land Cover Mapping
Air photo interpretation -- applications
Archaeology, Soils, Agriculture, Forestry, Geology, Engineering, etc.

Photogrammetry

Principal point, conjugate principal point, nadir
Planimeters, stereoscopes, parallax bar
Types of measurements that can be made, uses
Parallax, relief displacement
Orthophotos

Satellite Imagery (and some airborne systems)

Analog vs digital data
Raster vs. vector, Pixels
Image sensors, data recording instruments
Multispectral scanning
Across track (whiskbroom) scanners: characteristics, advantages, disadvantages, uses
Along Track (pushbroom) scanners:characteristics, advantages, disadvantages, uses
Thermal scanning
IFOV -- Instantaneous Field of View
Image Resolution -- Spatial, Spectral
Spectral bands, characteristics
Electronic data, images: scan lines (rows) and columns (samples), data points, pixels

Satellites

Landsat series, 1-3 and 4-5, and 7
Return Beam Vidicon camera (RBV), MSS, uses, characteristics
Thematic Mapper (TM)
Orbital characteristics -- sun synchronous
Orbital period, Height, etc.
EROS -- Earth Resources Observation System

SPOT -- Systèm pour l'observation de la Terre

Sensors, characteristics, uses -- pointable, stereo

Image Processing

Digital Numbers (DNs)
Statistical analysis of image -- histogram, mean, standard deviation, skewness

Image Rectification, Restoration, Preprocessing

Geometric correction
remove skew distortion
random distortions -- ground control points
resampling
Radiometric correction -- normalizing brightness
Noise removal, destriping, line drop errors, bit errors -- speckless
Haze removal
Sun angle correction

Image Enhancement -- methods, results, purposes

Gray-level thresholding (binary mask created)
Level slicing
Contrast stretching, data histograms
Linear stretch
Sinusoidal stretch
Spatial filtering
Low pass filter -- low frequency (gradual DN changes)
High pass filter -- high frequency (abrupt DN changes)

Edge Enhancement -- method, uses

High pass filter, add back original data, then apply linear stretch
Multispectral band ratioing, Method, Uses

Simulated MSS natural color images --method

Image Classification

Supervised, Unsupervised
Procedures -- Training, statistical parameters, data classification, evaluation, and refinement, documentation
Output -- maps (land cover, thematic), tables, digital files
FINAL EXAM SAMPLE QUESTIONS

SHORT ANSWER (Relatively). Answer each question with a few words or phrases, and a sketch where requested or helpful. Be sure to answer ALL PARTS of each question. Single words are not sufficient. (3 pts each)

1. What are the advantages and disadvantages of Across Track scanners (whiskbroom) and their images compared with Along Track scanners (pushbroom) and their resulting images?

 

 

 

2. What are the similarities and differences between Landsats 1-3 and Landsats 4 and 5, in terms of (a) types and (b) spectral sensitivity of sensors carried, (c) orbital characteristics, and (d) image resolution?

 

 

 

 

3. What types of image processing techniques would you use to solve the following problems: (a) remove image noise, such as stripes or banding and bit errors; (b) accentuate different vegetation types by bringing out differences in spectral reflectance (or color); and (c) clarify boundaries and enhance high frequency details.

 

 

4. Image Classification: (a) What is the purpose of image classification? (b) Briefly, what is involved in "training" the image processor to categorize different surface cover types? (c) What are two basic differences between "unsupervised" and "supervised" image classifying?

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