1. Remote Sensing and Image Interpretation
Speaker
Shagufta Akbari
Assistant Prof.
KL University

2. contents Introduction Map as a model Spatial elements and terminology
Classification of Maps
Map Scale
Spatial referencing system
Computers in map production
General software’s in map production
Types of data products

3. Continued …… Image interpretation strategy
Levels of interpretation keys
Topography
Types of Drainage pattern and Texture
Erosion
Process of image interpretation
Basic elements of image interpretation
Overview on visual image interpretation equipment

4. Map as Model Representation of features of earth drawn to scale
“A map is a very powerful tool and maps are typical reductions which are smaller than the areas they portray” (Robinson et.al 1984)

5. Spatial elements and terminology
Spatial objects in the real world can be thought of as occurring in four easily identifiable types namely, points, lines, areas and surfaces
Points, lines and areas can be represented by using symbols to depict the real world.
Surfaces are represented by any combination of these spatial entities.
In general, all the geographic surfaces are in two tangible forms, namely, discrete and continuous.
Trees, houses, road intersections and similar items are discrete spatial features.

6. Classification of Maps
On the basis of scale
Small scale map
Large scale map- urban plan map, transportation and network map

7. Map Scale
The ratio between the reduced depiction on the map and the geographical features in the real world is known as the Map Scale
Scale expressed in three ways:
Fractional scale-the method of representing this type of scale is called representation fraction method

8. In India commonly used fractional map scales are 1:1,00,000,00; 1:250,000, 1:50,000; 1:25,000 and 1:10,000
Graphical Scale- A line printed on the map and divided into units that are equivalent to some distance
The measured ground distance appears directly on the map in graphical representation
Verbal Scale- This is an expression in common speech like “an inch to a mile”

9. Spatial referencing system
To locate objects with respect to some reference system
Methods of spatial referencing systems
Geographic coordinate systems-
Denoted by latitude and longitude
Rectangular coordinate systems(RCS)
Spatial data are in two-dimensional form
Relative position- location of any point on the earth’s surface w.r.t RCS
Non- coordinate systems
Spatial reference with descriptive codes such as postal codes which is numeric in nature

10. Computers in map production
Advantages
To make existing maps more at a quicker pace
To make existing maps at a cheaper rate
To make maps for specific user needs
To make map production possible in situations where skilled staff are unavailable
To allow experimentation with different graphical representations of the same data

11. Continued…
To facilitate map making and updating when the data are already in digital form
To minimize the use of the printed map as a data store and thereby to minimize the effects of classification and generalization on the quality of the data
Introduction of automation can lead to a review of the whole map – making process , which can also lead to savings and improvements
To create maps in which selection and generalization procedures are explicitly defined and consistently executed

12. General software’s in map production
Arc- GIS
ARC- VIEW etc.

13. Raw data: radiometrically and geometrically uncorrected data
Types of data products
Depending on correction applied & level of processing
RS data products
Photographic products such as paper prints, film negatives, diapositives of black and white and FCC False color composite
Digital form CCTs computer compatible tapes
RS data products
Raw data: radiometrically and geometrically uncorrected data
Standard data: radiometrically and geometrically corrected data
Geocoded products:data: products are north oriented and compatible to survey of India mapsheet
Precision product: radiometrically and geometrically corrected data with the use of GCP to achieve greater locational accuracy
Geocoded products:data: systematically & geometrically corrected products :data: products are north oriented and compatible to survey of India mapsheet
It means overlays of this data with survey of india map can be performed
Note: FCC are generated by combininig the data contained in three spectral bands respectively. The choice of band combinations can be determined depending upon application

14. Image interpretation strategy
Visual image interpretation : Process of indentifying what we see on the images and communicate the information obtained from these images to others for evaluating its significance
Includes relative locations and extents
Use of data products like Satellite single band imageries, FCC for performing image interpretations to extract thematic information for subsequent input to GIS

15. Levels of interpretation keys
Interpretation Keys: Criterion for identification of an object with interpretation elements

16. Basic elements of image interpretation
X, Y location
size
shape
shadow
Tone
colour
Texture
Pattern
Height & Depth
Site, Situation & Association

17. Size Size of objects in an image is a function of scale
Proper photo scale selected depending on the purpose of interpretation
Most commonly measured parameters:- length, width, perimeter, area and occasionally volume

18. Shape
Shape of an object is described as the geometric form represented form represented on an image
Regular shapes are signs of man-made objects
Irregular shapes with no distinct geometrical pattern are signs of a natural environment
Regular shapes are signs of man-made objects- buildings, roads and cultivated fields
Irregular shapes with no distinct geometrical pattern are signs of a natural environment- water body or a river

19. Shadow Shadow – usually a visual obstacle for image interpretation
Gives height information about towers, tall buildings H
object S
Shadow

20. Tone
Band of EM spectrum recorded by RS system may be displayed in shades of grey ranging from black to white
Tone:-
continuous grey scale varying from white to black
It refers to relative brightness or colour of objects in an image
Note:- Humans differentiate individual shades of grey RS image
For eg. In panchromatic photograph Dry sand appears white, while wet sand appears black

21. Colour
more convenient for the identification of object details
Texture
Characteristics placement & arrangement of repetitions of tone or colour in an image
Visual impression of roughness or smoothness of an image region