Instructor: Dr. M. M. Yagoub
URL:
https://www.angelfire.com/mo/yagoub
Questions and Answers (Q/A)
Textbook:
Thomas Eugene Avery and Graydon Lennis Berlin, Fundamentals of Remote Sensing and Airphoto Interpretation,
Fifth Edition, Macmillan Publishing Company, New York, 1992.
Correct answers are shown in italic and color
Q1.The basic equation of electromagnetic is
C = & f where
A- C, &, f
stands for speed of light, altitude, and force
B- C, &, f
stands for speed of light, wave length, and frequency
C- C, &, f
stands for current, speed of light, and force
Q2. The main effects of the atmosphere on electromagnetic
radiation are:
A-
Cloud and rain
B- Reflection and refraction
C-
Scattering and absorption
Q3. The following percentage is recommended as
forward overlap (end lap)
A- 5-15%
B- 20-40%
C- 50-60%
A- Color
and shading
B- Tilt and relief displacement
C-Camera
and height
Q5. Mosaic can be defined as:
A-
Overlapped maps B-
Overlapped papers
C- Overlapped photos
Q6. A hardcopy photograph can be converted to digital copy by:
A-
Copier
B- Printer
C- Scanner
Q7. Orthophoto can be defined as:
A-
Overlapped maps
B- corrected photos C-
Overlapped photos
Q8. To obtain 3D from aerial
photographs, we must have:
A- A lens
B- Stereo-pair C- Aero-plane
Q9. Relief displacement which is
encountered in aerial photographs is due to:
A- Color
of objects
B- Wind direction
C- Height of objects
Q10. The followings are used as
indicators in photo interpretation:
A- Shape, size, color B- length, width,
diameter
C- Number of Bands
Section B
Define remote sensing?
Remote sensing
is a technology of obtaining information about the environment from non contact
sensor system (eye, camera, sensors). This definition considered photography as
sub-field of remote sensing.
Define Photogrammetry?
Photogrammetry
is the science or art of obtaining reliable measurements (distance, angle, area, elevation) from aerial photography (aero-plane, aerial camera)
Draw a figure showing the main regions of electromagnetic spectrum?
Refer to the text book: page 2-
Figure 1-2
The electromagnetic spectrums that are commonly
used in remote sensing are:
-
Visible
to human eye (0.4-0.7 um) colors – RGB
-
Infrared
(0.7-1000 um) – reflected/emitted thermal radiation (temperature of objects)
-
Microwave
(0.1 mm - 100 cm)- Active system (RADAR-back scattering, SLAR)
Atmosphere effects are caused primarily by
scattering
and absorption.
Draw a figure showing
the main components of an aerial camera
Refer to the
text book: page 26- Figure 2-13
List the main information that
must be included in an aerial photo, illustrate by figures?
Fiduicial marks (< >)
-
Focal length (f)
-
Date and time of the day
Photo scale
List the main measurements
that can be derived from an aerial photo? (Refer
to the text book: page 58-67, 80-86)
- Horizontal distance (ruler, scale of photo)
Angle or direction (Protractor)
- Area (using dotted grid or digital planimeter)
- Elevation (3D- Stereoscope – stereo-pair photos)
List Five (5) remote sensing web
sites? Check course outline in the internet
Define photo
interpretation?
Photo interpretation is a process of extraction of natural (e.g. river) and artificial (e.g. buildings) features from an aerial photo.
What is the difference between visual
interpretation and digital image
classification?
- Visual interpretation depends on human eye and it is usually depends on the skill of the
operator, experience, and knowledge of the area (mainly used in interpreting aerial photos). Photo interpretation can
be supported by magnifying lens
and stereoscope (pocket, mirror)
-
Digital image classification is based on using computers instead
of human eye ((mainly used in
classification of remote sensing imagery)
List the main indicators used
in photo interpretation?
Refer to the text book:
page 51-57
Features on a photo can be delineated based on the following
characteristics:
– Tone (B/W -gray shade, color and brightness)
– Size (depend on scale e.g. size of house or hostel)
– Shape (geometrical arrangement, road/house; non-geometric e.g.
lake, river)
– Texture (smoothness or roughness: water, grass, trees)
– Pattern (spatial arrangement, network of streets, farms, orchards
not forest)
– Shadow (height of object, high buildings)
– Site (geographic location, features on rivers)
You are required to cover Abu Dhabi
by aerial photographs, list all the
necessary steps (Hint: flight plan details), illustrate by figures?
Refer to page 59 and
Chapter 5: page 95-107
-
Flight plan must
calculate the total area to be covered and its direction (north-south,
east-west)
- Select scale of photography, focal length of the
camera to be used, and flying height
- Determine forward and side over lap required. Usually
50-60% is recommended as forward overlap (End-lap) between successive
photographs in the same flight-line and 5-15% is recommended as a side lap
between adjacent flight lines
- calculate ground distance for each flight line, number
of photos, and other parameters
Define a mosaic? Refer to page 93
An aerial mosaic is an assemblage of two or more individual over lapping photographs to form a single continuous picture of an area.
Define photomap?
Names and other information such as title, north
arrow, legend, and scale can be added to the mosaic to produce a photomap i.e.
photo + map
List the main problems
encounter in aerial photograph?
-Tilt: due to wind
- Relief displacement : due to change in elevation of
objects
Define Orthophoto? Refer to page 90
An orthophoto is a corrected photo
in which the problems (tilt, relief displacement) are removed
Define stereo-pair
photos?
Stereo-pair photos are two
consecutive photos taken on the same flight line.
Discuss briefly how to use aerial
photography to study desertification creep in the UAE?
Determine the
scale of a photo if its focal length is 210 mm and flying height is 6000 m
above mean sea level? ? Refer to page 73
Solution:
Photo scale = F/H = 210/6000x1000 = 1:28571
Determine the
scale of a photo if its focal length is 210 mm, flying height is 6000 m above
mean sea level, and average ground elevation is 300 m?
Refer
to page 73
Solution:
Photo scale =
F/ (H-AH) where AH = average elevation
= 210/ (6000-300)x1000= 210/5700x1000 =
= 1:27143
* Try other numbers
