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Lecture # 02 Part-II Dated: 21/10/14 Subject Database Management Information System & Applications of Remote sensing and GIS Section-II “Applications of Remote sensing and GIS” Topic: “Introduction to Image Interpretation” Presented by Rehana Jamal 1 Lecture#2 Part-II Subject Dated:21/10/14 Database Management Information System & Applications of Remote sensing and GIS Section-II “Applications of Remote sensing and GIS” Topics 1. INFORMATION EXTRACTION IN REMOTE SENSING 2. IMAGE INTERPRETATION 3. INTERPRETATION ELEMENTS/KEYS 2 1. INFORMATION EXTRACTION IN REMOTE SENSING “Remote sensing is the technology allowing to obtain information of an object, area or phenomenon by means of data coming from an apparatus, which is not in physical contact with this object, area or phenomenon.” In practice, this means that the information of the Earth's surface is obtained by sensors mounted on an airplane or a satellite. Remote sensors record electromagnetic radiation emitted or reflected from the Earth’s surface. Different types of vegetation, soils and other features emit and reflect energy differently. 3 Process of information extraction from remote sensing *Energy Source or Illumination (A) *Radiation and the Atmosphere (B) *Interaction with the Target (C) *Recording of Energy by the Sensor (D) *Transmission, Reception, and Processing (E) *Interpretation and Analysis (F) *Application (G) 4 DIFFERENT TECHNIQUES OF INFORMATION EXTRACTION Remote sensing:is a technique of collecting information from a distance Remotely sensed data: The data collected from a distance 5 Definitions of Remote Sensing “Remote Sensing (RS) is the science and art of acquiring information (spectral, spatial, temporal) about material objects, area, or phenomenon, without coming into physical contact with the objects, or area, or phenomenon under investigation” OR “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” 6 Two main categories of Spatial data acquisition Ground based methods Real world Observation & measurements Spatial database Remote sensing methods Real world Sensors Image data Observation & measurements Spatial database 7 Topic:2 “Image Interpretation” Photographic Interpretation can be defined as: “the act of examining photographic images for the purpose of identifying objects and judging their significance” (Colwell, 1997). 8 Image Interpretation (visual analysis) 9 NEW CAMPUS(PU), LAHORE 10 Can you interpret Old CIMR in PU, Lahore? 11 Can you interpret New CIMR in PU, Lahore? 12 What is Dead Ground Effect? 13 Image Interpretation of Dead Ground Effect 14 Image Interpretation (visual analysis) Photographic Interpretation can be defined as: “the act of examining photographic images for the purpose of identifying objects and judging their significance” (Colwell, 1997). 15 Two methods of information extraction from remote sensing imagery Information extraction based on visual analysis or interpretation of data e.g. land use, soil map, updating of topographic maps from aerial photographs Information extraction based on semi-automatic processing by computer e.g. automatic generation of DTM, image classification and calculation of surface parameters 16 1st Method Image understanding and Interpretation Human Vision Interpretation elements Stereoscopic vision 17 1- Human Vision Two situations of human vision: i. Direct and spontaneous recognition ii By a reasoning process(logical inference) Direct and spontaneous recognition----refers to the ability of an interpreter to identify objects or phenomena at a first glance. By a reasoning process (logical inference) ---In the reasoning interpreter will use his professional knowledge & experience. If reasoning cannot help then field observation is required 18 Direct and Spontaneous recognition 19 By a reasoning process 20 2- Interpretation elements “A set of terms required to express and define characteristics present in pictures (that are visualized in image data) are called Interpretation elements.” e.g. i. ii. iii. iv. v. vi. vii. Tone/Hue Texture Shape Size Pattern Site Association 21 2- Interpretation elements/Keys 1. Tone/Hue--- relative brightness of black and white image 2. Texture--- refers to the colour on the image as defined in the Intensity, Hue ,Saturation (HIS)system 3. Shape--- form characteristics many terrain objects visible in the image 4. Size--- relative or absolute 5. Pattern--- refers to the spatial arrangement objects e.g. concentric, radial--irrigation and housing have different pattern 6. Site--- relates to the topographic or geographic location 22 7. Association--- refers to the fact that a combination of objects makes it possible to infer about its meaning or functioning 3- Stereoscopic Vision The impression of depth in real world can be realized by the pair of images of the same object taken from different positions. Such a pair of images, photographs or digital images that are separated and observed at the same time by the two eyes give images on the retinas in which objects at different positions in space are projected on relative different positions. This is called Stereoscopic Vision Stereo grams---Pairs of images that can be viewed stereoscopically are called Stereo grams. Convergence---Focusing both eyes to the object(point) of interest is called convergence. 23 Pocket and Mirror stereoscope Pocket stereoscope with original test image. Used by military to examine stereoscopic pairs of vertical aerial photographs. 24 Pocket and Mirror stereoscopes Uses in Mapping applications Vegetation Forest Soil Geomorphology 25 Photogrammetric plotters Uses Topographic Mapping Large scale Mapping 26 Anachrome "compatible" color anaglyph method Anachrome optical diopter glasses 27 Anaglyphs 28 Stereoscopic Vision and 3D Technology 29 Process of visual image interpretation Selection of image data and its hard copy prints Use of transparencies to overlay on hard copy print of image for interpretation Digitization of Point, Line & Polygon features in the form of line patterns on transparencies having class codes & land cover codes. Validation: independent assessment of accuracy 30 Task on Analogue image Interpretation Bring the following stationary in the next class: Permanent markers of red, green, blue and black Six A4 size transparencies Print of the given image having size of 2 by 2 feet 31 References: www.google.com “Principles of Remote sensing” by Lucas L.E. Janssen Recommended websites for notes http://userpages.umbc.edu/~tbenja1/umbc7/santabar/vol1/lec2/2-3.html http://en.wikipedia.org/wiki/Aerial_photographic_and_satellite_image_in terpretation http://www.nrcan.gc.ca/earth-sciences/geography-boundary/remotesensing/fundamentals/1223 32