midterm 2nd lesson

Question 1

Employs polynomial regression equations of different
degrees to relate image coordinates and their
corresponding map coordinates

Answer 1

POLYNOMIAL

Question 2

A form of rectification that corrects for terrain
displacement using a DEM of the study area

Answer 2

ORTHORECTIFICATION

Question 3

Use methods based on statistical operations:
“Ground Control Point rectification” _________________

Answer 3

(Star & Estes
1990).

Question 4

The distance between the GCP reference
coordinate and the curve is expressed as the
__________________________

Answer 4

Root Mean Square Error (RMSE)

Question 5

Due to time taken to build an image as the
sensor scans the earth surface features

Answer 5

Earth Rotation

Question 6

is the application of a coordinate
system in the image

Answer 6

RECTIFICATION

Question 7

refers to assigning map
coordinates to image data

Answer 7

Georeferencing

Question 8

In relatively flat areas, this is not necessary, but
in mountainous areas (or on aerial photographs
of buildings), where a high degree of accuracy is
required.

Answer 8

ORTHORECTIFICATION

Question 9

Because data are sampled at regular intervals,
this produces ________ distortion

Answer 9

along-scan distortion

Question 10

Forms the preparatory phase for later analysis

Answer 10

Image Rectification and Restoration
(Pre-Processing)

Question 11

uses the weighted average
of 16 pixels to resample
the image; the processing
is significantly the slowest

Answer 11

Cubic Convolution

Question 12

To correct image data for distortions or
degradations that stem from the image acquisition
process

Answer 12

Image Rectification and Restoration
(Pre-Processing)

Question 13

can be used on very distorted
aerial photographs

Answer 13

4th-order transformations

Question 14

__________, by definition, involves
__________, since all map projection systems
are associated with map coordinates.

Answer 14

rectification, georeferencing

Question 16

The mirror scanning rate is usually not constant
across a given scan, producing along-scan
geometric distortion

Answer 16

Mirror Scan Velocity Variance

Question 17

The process of correcting non-linear distortions is also known
as ___________.

Answer 17

rubber-sheeting

Question 18

The warping fits triangles to the irregularly spaced
GCPs and interpolates values to the output grid.

Answer 18

TRIANGULATION

Question 19

The image is stretched to fit most of the coordinates.

Answer 19

Rubber-sheeting

Question 20

Errors are given as________ error
that denote difference between output location for a
GCP and the real coordinates for the same point
when the point is recalculated via a matrix of
transformation

Answer 20

RMS(Root Mean Square)

Question 21

registration involves
georeferencing only if the reference image is
already georeferenced

Answer 21

Image-to-image

Question 22

To perform RST warping, you need ________________
GCPs.

Answer 22

three or more

Question 23

The ground area imaged is proportional to the
tangent of the scan angle rather than to the angle
itself

Answer 23

Panoramic Distortion

Question 24

e.g. Adjust DNs for effect of hazy atmosphere

Answer 24

Radiometric correction or preprocessing

Question 25

If the speed of the platform changes, the ground track covered by successive mirror scans changes, producing along-track scale distortion

Answer 25

Platform Velocity

Question 26

Due to spacing of detectors and regular sampling

Answer 26

Panoramic Distortion

Question 27

can be used to convert Lat/Lon data to a planar projection, for data covering a large area (to account for the Earth’s curvature), and with distorted data (for example, due to camera lens distortion).

Answer 27

2nd-order transformations

Question 28

effect of platform position and attitude variations

Answer 28

altitude spacecraft velocity pitch roll yaw

Question 29

Correcting for geometric distortions due to sensor-Earth geometry variations (e.g. Earth’s rotation), and conversion of the data to real world coordinates (e.g. latitude and longitude) on the Earth's surface.

Answer 29

Geometric correction

Question 30

Statistical approach establishes mathematical relationship between image coordinates and their corresponding map coordinates using standard statistical procedures by means of a GCP data set.

Answer 30

GCP Rectification

Question 31

the distances between the source and retransformed coordinates in one direction shown for each GCP.

Answer 31

Residuals

Question 32

Many factors contribute to the distortions, what are these?

Answer 32

▫ Cross-track scan error ▫ Curvature of the earth ▫ Panoramic distortion ▫ Scan Skew ▫ Earth rotation ▫ Platform velocity ▫ Mirror scan velocity

Question 33

* ___________________ arise from ▫ Sensor system’s attitude, velocity, and altitude ▫ Can be corrected only through the use of ground control points (GCPs) ▫ In particular, topographic, or relief displacement due to terrain variation is usually the most serious of the displacement types, especially in mountainous terrain

Answer 33

Non-systematic distortions

Question 34

Caused by the forward motion of the platform during the time required for each mirror sweep. The ground swath is not normal to the ground track but is slightly skewed, producing cross scan geometric distortion

Answer 34

Scan Skew

Question 35

The geometric distortions inherent in remote sensing images fall into two categories, what are these categories?

Answer 35

systematic distortions non-systematic distortions

Question 36

are used with distorted aerial photographs, on scans of warped maps and with radar imagery

Answer 36

3 rd -order transformations

Question 37

-the simplest method of warping

Answer 37

RST (Rotation, Scaling, and Translation)

Question 38

Use of __________ -- points that can be identified in the image whose exact location is known in chosen coordinate system

Answer 38

“control points”

Question 39

the weighted average (linear interpolation) of the DNs for the four pixels surrounding the transformed output pixel is used.

Answer 39

Bilinear Interpolation

Question 40

This triangle-based rectification should be used when other rectification methods such as polynomial transformation and photogrammetric modeling cannot produce acceptable results.

Answer 40

Rubber-sheeting

Question 41

This type of distortions can be rectified using data from platform ephemeris and knowledge of internal sensor distortion.

Answer 41

Systematic distortion

Question 42

A function of the distance from the sensor to the target, the IFOV, and the scan angle off nadir

Answer 42

Cross-track Scan Error

Question 43

No remote sensing images are free of geometric distortions and an essential requirement for integrated processing of remote sensing images and data from geographic information systems (GIS) is that they are spatially referenced.

Answer 43

GEOMETRIC DISTORTIONS

Question 44

the transformed pixel takes the value of the closest pixel in the pre-shifted array without interpolation

Answer 44

Nearest Neighbor

Question 45

Can be corrected using a “rubbersheet” rectification based on ground control points

Answer 45

TERRAIN-RELATED DISTORTION