Presentation on theme: "Remote Sensing and Image Interpretation"— Presentation transcript:
1 Remote Sensing and Image Interpretation SpeakerShagufta AkbariAssistant Prof.KL University
2 contents Introduction Map as a model Spatial elements and terminology Classification of MapsMap ScaleSpatial referencing systemComputers in map productionGeneral software’s in map productionTypes of data products
3 Continued …… Image interpretation strategy Levels of interpretation keysTopographyTypes of Drainage pattern and TextureErosionProcess of image interpretationBasic elements of image interpretationOverview 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 surfacesPoints, 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 scaleSmall scale mapLarge scale map- urban plan map, transportation and network map
7 Map ScaleThe ratio between the reduced depiction on the map and the geographical features in the real world is known as the Map ScaleScale 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 1:10,000Graphical Scale- A line printed on the map and divided into units that are equivalent to some distanceThe measured ground distance appears directly on the map in graphical representationVerbal 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 systemMethods of spatial referencing systemsGeographic coordinate systems-Denoted by latitude and longitudeRectangular coordinate systems(RCS)Spatial data are in two-dimensional formRelative position- location of any point on the earth’s surface w.r.t RCSNon- coordinate systemsSpatial reference with descriptive codes such as postal codes which is numeric in nature
10 Computers in map production AdvantagesTo make existing maps more at a quicker paceTo make existing maps at a cheaper rateTo make maps for specific user needsTo make map production possible in situations where skilled staff are unavailableTo 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 formTo 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 dataIntroduction of automation can lead to a review of the whole map – making process , which can also lead to savings and improvementsTo create maps in which selection and generalization procedures are explicitly defined and consistently executed
12 General software’s in map production Arc- GISARC- VIEW etc.
13 Raw data: radiometrically and geometrically uncorrected data Types of data productsDepending on correction applied & level of processingRS data productsPhotographic products such as paper prints, film negatives, diapositives of black and white and FCC False color compositeDigital form CCTs computer compatible tapesRS data productsRaw data: radiometrically and geometrically uncorrected dataStandard data: radiometrically and geometrically corrected dataGeocoded products:data: products are north oriented and compatible to survey of India mapsheetPrecision product: radiometrically and geometrically corrected data with the use of GCP to achieve greater locational accuracyGeocoded products:data: systematically & geometrically corrected products :data: products are north oriented and compatible to survey of India mapsheetIt means overlays of this data with survey of india map can be performedNote: 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 significanceIncludes relative locations and extentsUse 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 locationsizeshapeshadowTonecolourTexturePatternHeight & DepthSite, Situation & Association
17 Size Size of objects in an image is a function of scale Proper photo scale selected depending on the purpose of interpretationMost commonly measured parameters:- length, width, perimeter, area and occasionally volume
18 ShapeShape of an object is described as the geometric form represented form represented on an imageRegular shapes are signs of man-made objectsIrregular shapes with no distinct geometrical pattern are signs of a natural environmentRegular shapes are signs of man-made objects- buildings, roads and cultivated fieldsIrregular 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 buildingsHobjectSShadow
20 ToneBand of EM spectrum recorded by RS system may be displayed in shades of grey ranging from black to whiteTone:-continuous grey scale varying from white to blackIt refers to relative brightness or colour of objects in an imageNote:- Humans differentiate individual shades of grey RS imageFor eg. In panchromatic photograph Dry sand appears white, while wet sand appears black
21 Colourmore convenient for the identification of object detailsTextureCharacteristics placement & arrangement of repetitions of tone or colour in an imageVisual impression of roughness or smoothness of an image region
Your consent to our cookies if you continue to use this website.