introduction to gis
DESCRIPTION
Introduction to GIS and ESRI ArcGIS ProductsTRANSCRIPT
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What is GIS?
GIS = Geographic Information System
A GIS integrates hardware, software and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.
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Data Representation
● GIS data represents real world objects (e.g. roads, land use, elevation, trees, waterways, etc.)
● There are 2 broad methods used to store data in GIS1. Vector data model2. Raster data model
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Data Representation (Vector)
1. PointsLocation of Wells, Schools, or Points of Interest
2. Lines / PolylinesRoad Centerlines, Rivers, Trails, or Streets
3. PolygonsBoundary of Cities, Lakes, or Forests
A coordinate-based data model that represents geographic features as points, lines, and polygons.
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Raster as Elevation Surface
Data Representation (Raster)
Raster as Satellite Imagery
A spatial data model that defines space as an array of equally sized cells arranged in rows and columns. Each cell contains an attribute value and location coordinates.
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Common GIS Data Format
Vector Data Model● Shapefile (.shp, .shx & .dbf)● Geography Markup Language GML (.gml)● Personal Geodatabase (.mdb)● File Geodatabase (.gdb)
Raster Data Model● Enhanced Compressed Wavelet ECW (.ecw)● GeoTIFF = TIFF file with GeoReference (.tif)● MultiResolution Seamless Image Database MrSID (.sid)● JPEG2000 = JPEG file with GeoReference (.jpg)
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Coordinate Systems
Geographic Coordinate Systems● WGS84 (Latitude and Longitude) is the most
commonly used Geographic Coordinate System● Hong Kong = 22° 16′ 42″ N, 114° 9′ 32″ E
Projected Coordinate Systems● Project the earth 3D curved surface to a 2D flat surface● Hong Kong 1980 Grid (HK80Grid) is the coordinate
system for Hong Kong GIS data
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ESRI ArcGIS for Server
● Publishing GIS Web Services
● Creating Web Mapping Applications
● Administering ArcGIS for Server
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Geodatabase (ArcSDE)
● ArcSDE = Spatial Database Engine● Core component of ArcGIS for Server● Primary data storage model for ArcGIS● Centralized location to access and manage spatial data● Major Features
○ Versioning○ Geodatabase Replication○ Geodatabase Archiving
● Support Microsoft SQL Server, Oracle, etc.
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ESRI ArcGIS for Desktop
ArcMap● View, Edit and Query geospatial data, and Create
Maps
ArcCatalog● Manage geospatial data● Browse datasets, files, database or other sources
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3 Takeaways
1. GIS data represents real world objects in layers
2. There are 2 major data model in GISa. Vector = Point, Line, Polygonb. Raster = Cells with Values
3. Global Coordinate System = WGS84 (Sphere)HK Coordinate System = HK80Grid (Flat)
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