Geographic Information System Geographical Information System Geographical Information Science
and Techniques of G of Geographic by C.P.Lo and Albert Information Systems Systems by Yeung´ GIS is a set of computer-based systems for managing geographic data and using these data to solve spatial problems. Some people call it Spatial Information System System as well.
Geographic / Spatial Data (multidimensionality ). ).
Cartographic Cartograph ic application.
Information Systems and Anal Analysis Tool.
Problem: Find the nearest Bank ATM from our office building. A problem in Topology Topolog y ? A problem of ordering of 2D points in space ? A spatial analy anal ysis problem.
GIS is about spatial data, Information Sy System, stem, Cartographic application, and spatial anal ysis tool. Some people even call them as Spatial Decision Support Su pport Systems (S (SDSS).
Find the route between two locations in a cit y. A problem in Graph Theor y ? A problem in Operations Research ? A spatial anal ysis problem.
The website of MapQuest or R or RouteGURU outeGURU is an example of a web-based spatial decision support system which solves this problem.
So GIS also includes the people using it !
Maps and GIS GIS as a Cartographic Application
Cartographer / GIS GIS specialist
Recognize Select Classify Simplify Symbolize
image of reality
Read Analyze Interpret Map
Map Scale The scale of a map is the ratio or proportion between the distances measured on the map and the corresponding corresponding distances measured on the ground. You can do the mathematics. m athematics.
lasses of Maps 1) General Purpose or R or Reference maps: maps: hese are maps not designed for any any specific applications. This class of maps ocus on locations and shows a variety variety of phy physical and cultural features such as rainage, roads, railway railways, airports, forest and cultivate areas etc. They They serve as he base maps for developing and integrating other form of geographic information. ) Special Purpose or Thematic maps: maps: hese maps are designed to depict a particular ty type of feature or measurement nly nly. Like it can show the variation of rainfall across certain region. These maps re generated using the base maps.
Shape of Planet Earth?
Datum is a set of reference p reference points oints on the ea earth's surf ace aga against inst which p which position osition mea measurements are mad ade, e, and an associ ssociaate ted d mo mod del of the shap shapee of the ea earth to define a geo eog gr aphic aphic coor din inaate system. Horizontaal da Horizont datums tums are used used for for d describin escribing g a p point oint on the ea earth's surf ace, in la latitu titud de and lon long gitu itud de Verticaal da Vertic datums tums mea measure eleva elevations or d or de p pths ths
Cartesian coordinate sy system
Geographic coordinate sy system
Y -X + Y
+X + Y X
line passin line pa ssing g throu throug gh the (former) Roya Royal Observa Observatory, Greenwich is the zero-long zero-longitu itud de reference line. Greenwich Meri erid dian. Equaator is the line at Zero degree la Equ latitu titud de.
am assuming t=to in this problem also for time being !
Semi-Maj emi-Major or Axis Semi
Minor Axis Fla Flattening ttening
Latitud Latitu de is vertica vertical angle Lon ong gitu itud de is the horizonta horizontal angle.
ap p pro jection A map ro j ection is a system systemaatic re p re present resentaation of aall of ll pa part rt of the surf ace of a of a roun round d bo bod dy es p peci eciaally ea earth on a p pllane.
Projection systems Re p present resent the twotwo-d dimension imensionaal curve curved d surf ace of the earth on a p pllane
Shape Scale Area Direction Distance
Map p Map pro ro jections jections ca can be constructed constructed to p to preserve reserve one or some of these p these pro ro perties, perties, thoug though not all of them simulta simultaneously.
For an application like MapQuest/R MapQuest/ outeGURU Route GURUTM you would need a map projection that would preserve the distance as it involves distance based calculations for finding the shortest route.
As f ar r aas p pro ro j jections ections is concerned concerned j just ust mak mak e sure tha that all the la layers you overla overlay are in the same me p pro ro j jection ection
Sources S pa pati tiaal
of S pa pati tiaal Da Data
data for the gener al p dat pur ur p pose ose and reference map mapss for GIS are collected collected usin using g the method metho ds of la land surveyin surveying g, aeri eriaal and satellite phot p hotg gr ammetry and glob lobaal p positionin ositioning g system (GPS)
Globa Global Positioning ositioning System
Attribute or Non S pa pati tiaal Da Data The
Non-S pa pati tiaal da datta can be collected collected usin using g method metho ds lik lik e surveys, census etc. which ca c an be used use d for thema thematic mapp mappin ing g.
Dig Di git itaal Re p Re present resentaation of Geog Geogr aphic aphic Da Data
Dig Di git itaal Re p present resentaation of Geog Geogr aphic aphic Da Data Contd. d fe reaal-worl re l-world feaatures exists in two different forms ob j ob jects ects and p phenomenon. henomenon. The
Ob j jects ects are discrete and definite hence ca can be re p re presente resented d using usin g p point oint or line or p or poly olyg gon which is Vector Format. Phenomenon
is distribute istributed d over over aa lar ge are reaa such ha h as elevaation or clima elev climate etc. which is re p re presente resented d in Raster Format.
Digital Representation of Geographic Data Components
Other to p to pics ics Dig Digitiz itizaation (Vector Da Data Cre Creaation) S pa pati tiaal O p O per er ations Contaains, Overlap Cont Overlaps, s, Intersects, etc
S pati patiaal An Anaalysis on Vector Da Data Overlaay, Buffering Overl Buffering, Networ k An k Anaalysis, etc
Data Qu Quaality and Standa dar r ds Ch Chaallen lleng ges for L for LBS app applic licaations.
Open Source GIS UMN-Mapserver (O p pensource ensource mapp mappin ing g server for web-ba web-base sed d GIS applic app licaations. Ma Mainly inly in Ph p Map Mapscri scri p pt) t) QuantumG IS (Automaatic crea (Autom creation of Map of Map File) OpenMap API (O p pen en Source Mapp Mappin ing g API in Ja Java) PostGIS (S pa pati tiaal Extension to Post ostg greSQL) Simil imilaar to ORACL ORACLE S pa pati tiaal.