Aerial photography and photogrammetry are techniques used in remote sensing. Aerial photography involves taking photographs from aircraft and has been used since the 1850s. Photogrammetry uses photographs to measure and obtain spatial information about the objects and terrain photographed. It allows for the creation of topographic maps, cadastral maps, and large-scale construction plans more quickly and economically than traditional ground-based surveying. While aerial photography and photogrammetry provide advantages over field surveys, some on-site control and verification is still needed.

1. Introduction to Aerial
Photography and
Photogrammetry
T.SrinivasaRao

2. Study of Aerial photography -
Whether it may be
photogrammetry or interpretation -
is subset of a large discipline
called "Remote Sensing"

3. What is Remote
Sensing?
• Remote sensing is the science and art of
obtaining information about an object, area, or
phenomenon through the analysis of data
acquired by a device that is not in contact with
the object, area, or phenomenon under
investigation

4. Aerial Photography
• The term "photography" is derived from two Greek
words meaning "light" (phos) and "writing" (graphien).
• Photography is production of permanent images by
means of the action of light on sensitized surfaces (film
or array inside a camera), which finally giving rise to a
new form of visual art.
• Aerial Photography means photography from the air

5. Aerial Photography
• Aerial Photography is one of the most common,
versatile and economical forms of remote sensing.
• It is a means of fixing time within the framework of
space (deLatil, 1961).
• Aerial photography was the first method of remote
sensing and even used today in the era of satellite
and electronic scanners. Aerial photographs will still
remain the most widely used type of remote sensing
data.

6. • 1858 - Gasper Felix
Tournachon "Nadar"
took the first aerial
photograph from a
captive balloon from
an altitude of 1,200
feet over Paris.
Aerial Photography

7. Aerial Photography

9. Aerial Photography

10. 1908, Julius Neubronner

11. • Between 1887 and
1889, Arthur Batut
took aerial shots of
the South of
France using just
a kite, a camera.
1887 and 1889, Arthur Batut

12. Aerial photography
• Between 1887 and 1889, Arthur Batut took aerial shots of the South of
France using just a kite, a camera.
• In 1908, Julius Neubronner, who had used carrier pigeons in his work as an
apothecary, filed a patent for a miniature camera that could be worn by a
pigeon and would be activated by a timing mechanism.
• Pigeons were also used by the French to capture the position of the
German army in the First World War.
• Ref: http://www.newyorker.com/culture/photo-booth/origins-aerial-photography?
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13. Characteristics of Aerial
Photography
1. Synoptic Viewpoint: Aerial photographs
give a bird's eye view of large areas
enabling us to see surface features in their
spatial context. They enable the detection
of small scale features and spatial
relationships that would not be found on
ground.

14. Characteristics of Aerial
Photography
2. Time freezing ability: They are virtually permanent
records of the existing conditions on the Earth’s surface
at one point in time, and used as an historical document.
3. Capability to stop action: They provides a stop action
view of dynamic conditions and are useful in studying
dynamic phenomena such as flooding, moving wildlife,
traffic, oil spills, forest fires

15. Characteristics of Aerial
Photography
4. Three dimensional perspective: It provides a
stereoscopic view of the Earth’s surface and make it
possible to take measurements horizontally and vertically
- a characteristic that is lacking for the majority of
remotely sensed data.
5. Spectral and spatial resolution: Aerial photographs are
sensitive to radiation in wavelengths that are outside of
the spectral sensitivity of the human eye (0.3 µm to 0.9
µm versus 0.4 µm to 0.7 µm).

16. Characteristics of Aerial
Photography
6. They are sensitive to objects outside the spatial resolving
power of human eye.
7. Availability: Aerial photographs are readily available at
a range of scales for much of the world.
8. Economy: They are much cheaper than field surveys
and are often cheaper and more accurate than maps.

17. Photogrammetry - Introduction
• Photogrammetry is the science and
technology of obtaining spatial
measurements and other geometrically
reliable products from photographs.

18. Photogrammetry - Introduction
• The principal application of photogrammetry is to
determine the spatial position of the natural and man-
made features situated on the earth's surface
(topographic application).
• Photogrammetry is also used as a measuring tool in
architecture, industrial design, deformation studies of
structures, accident investigation, medicine etc. These
operations are referred to as non-topographic
applications.

19. Photogrammetry - Introduction
• Based on the location of sensor
– Terrestrial photogrammetry: Images aquired
by a ground based stationary sensor
• close range photogrammetry: Sensor present in
close vicinity to the target object.
– Aerial photogrammetry: Sensors mounted on
airborne platforms
– Space photogrammetry: Mounted on satellites

20. Methods for photogrammetric
measurements and processing
data
– Method 1: Requires complex instruments,
which physically model the geometric
relationship between the image and object at
the time of data acquisition.
– These instruments act as analogue computers
and the method is called as analogue or
instrumental photogrammetry.

21. Methods for photo..contd..!
– Method 2: Photogrammetric operations are
performed by mathematical modelling.
– This method is called analytical, numerical or
computational photogrammetry.
– The use of digital images is a special case
here. And because of the wide range of data
processing techniques available and the type
of instrumentation used here this class is
called as digital or softcopy photogrammetry.

22. • Objectives and priciples of surveying
adheres well with the photogrammetric
principles and hence, the images acquired
using photogrammetric principles can be
used for surveying complementing the on-
site surveys.

23. • Imaging has distinct advantages over data acquisition
by direct, on-site, measurement.:
– An image is a complete, comprehensive record of a scene or
situation as it existed at the instant of acquisition.
– It is a multilevel data set which can provide both quantitative and
qualitative information.
– Data acquisition can be accomplished within a short time over
large areas by imaging from the air or space.
– Processing and analysis of this data can be made at an
appropriate time and place, .distant from the scene and can be
repeated or augmented at will.
– The direct observation of directions and distances means point-by-
point measurement, while on images continuous measurements
can be made by tracing or delineating objects.

24. The weather and the seasons can place severe restrictions on the primary data
acquisition. On the other hand, under favorable conditions, images can be
acquired over a large tract of land within a short period oftime from the air or
from space.
It is not feasible to use aerial photography for the survey of small areas.
Equipment needed for the acquisition and processing of the data is more
expensive and more complex to operate than those used for surveying on site.
Photogrammetry is not an entirely selfsufficient spatial positioning process. A
certain amount of on-site observations are needed to control and verify the
analysis.
At the current state of the art, direct in situ measurements can provide the highest
possible accuracy for determining spatial positions.
Disadvantag
es

25. Applications of photogrammetry
Topographical mapping:
• The plotting of map detail and contours is normally carried out using
aerial photogrammetric methods
• These methods are used for both original survey and revision, and
replace classical ground methods except where the task is so small
that flying is uneconomical
• The technique needs a certain amount of ground surveyed control,
but this requirement is being continually reduced with the
improvement of aerial triangulation techniques to provide
supplementary control.
• A final Field check is necessary

26. Applications of photogrammetry
Large Scale Plans:
• Large scale plans can be produced
accurately and quickly by air survey
methods, but requires thorough checking.
• For large tasks such as road building and
major constructions, air survey methods
are quicker and cheaper than ground
methods.
• profiles for determination of earthwork
quantities can be simply obtained using
aerial photographs.

27. • Land use maps
• Hydrographic maps: mapping coast lines
etc.,
• Exploration and reconnaissance
• Terrestrial and Scientific uses
– Detailed surveying of historic buildings
– Traffic accidents
– Medical applications etc.,
• Stereoscopic applications and
measurements

28. Applications of photogrammetry
• Cadastral Maps:
• Similar types advantages compared
to large scale maps can be gained
here.
• Ground techniques are accurate but
not required in all cases.
• Air photo techniques provides
necessary information with adequate
accuracy.