gg5019 an introduction to geographical information technology and gis geographical information...
TRANSCRIPT
GG5019
An Introduction to An Introduction to
Geographical Information Geographical Information
Technology and GISTechnology and GIS
Geographical Information Geographical Information
Systems and Geospatial Systems and Geospatial
Data AnalysisData Analysis
David R. GreenG12 – 2324
ww
w.a
bd
n.a
c.u
k/g
eosp
atia
l
Objectives
Lecture 3
Objective
• GIS functionality
• GIS Data Sources• File Sizes• GIS Data Formats
GIS Functionality
•Display (Table/Map)•Visualise•Pan•Zoom (+/-)•Search•Information•Label
http://www.ess.co.at/toolkit/gis.htmlhttp://www.globalpositions.com/needsassessment.htm
GIS Functionality
•Convert to Shapefile•Select•Subset•Project•Measure (Distance/Area)
•Buffer•Query
GIS Functionality• Extensions
• GeoProcessing (Wizard)• Spatial Analyst (Proximity, Map Calculator, Statistics)• 3D Analyst (3D Visualisation)• Image Analyst (aerial photography / satellite imagery
• Animal Movement - http://www.absc.usgs.gov/glba/gistools/animal_mvmt.htm
• XTools - http://www.odf.state.or.us/divisions/management/State_forests/XTools.asp
• Beach Tools /Oceanographic Analyst
Data Sources
• Virtually any source and type of data can be input to a GIS providing it has a location (X-Y, Longitude-Latitude, Postcode or any other locational position)
• Both Analog and Digital data sources:• Traditional Maps (cartography) - digitising• Paper documents e.g. text files - scanning• Pictures (35mm camera) - digital / scanning• CAD drawings (engineering) - digital / digitising / scanning• Data Loggers (field data: temperature, soil moisture, contamination) - analog /digital• Questionnaires - digital / analog• Spreadheets and Databases - digital• Remote Sensing (including aerial photography and satellite imagery) - digital / scanning• Global Positioning Systems (GPS) - digital• Digital Camera and Video - digital• Multimedia GIS - most including ArcView and Idrisi are Multimedia in the sense that they can
handle any type and source of data
Filesize Calculations
•Scanners (black and white and colour)•Size of image to scan e.g. aerial photograph•Spatial sampling: dots per inch (dpi) or bits per inch (bpi)•Grey Scale/Colour depth: 2bit, 4bit, 8bit, 16bit, 32bit
•File formats: BMP, GIF, TIF, JPG, compressed etc….
•Bits, Bytes………………. Mb, Gb, Tb
True Colour Aerial Photograph:
e.g. (9”x300dpi) x (9”x300dpi) x 8bit = ?? Mb (approximate)
Colourdepth
128
dpi
dpi
Image (x)
Image (
y)
Online Data Sources
UK – Vector (and Raster) Map Data
•Ordnance Survey: http://www.ordnancesurvey.co.uk
•Edina Digimap: http://edina.ac.uk/digimap/
•UK Borders: http://edina.ac.uk/ukborders/
•English Nature: http://www.english-nature.org.uk/pubs/gis/tech_ds.htm
•MAGIC: http://www.magic.gov.uk/datadoc/summary.asp
Data Formats
• Vector and Raster data often stored within GIS software in different ways: data formats (the way in which data is arranged in the computer file)
• Different GIS have their own data formats for vector and raster data• ArcView, for example, uses the .shp shape format for Feature (or
map) data• The shape format has become almost (but not completely!) a vector
standard• It can be read (or imported) by most GIS software e.g. MapInfo• Usually vector formats are accompanied by additional files and formats
that contain additional information about or data associated with the vector format
Data Formats/File Extensions
• These files and file formats in ArcView come together with the .shp (map)
• They are: .shx (header file); .dbf (database file containing the associated table) (sometimes .sbx and .sbn also) Note: must be kept together whenever saved to disk or CD
• Image or Raster files come in many formats. The most common for GIS are: .TIF (Tagged Image File); .JPG (JPEG - Joint Expert Photographic Group; and GeoTIFF (a .TIF with map co-ordinates)
• JPGs (or JPEGs) can also have co-ordinates in a WORLD FILE (text file): if you remember the Nightphoto image had a Worldfile with it. World Files contain reference co-ordinates. These files can be opened and viewed in a text editor such as MS Wordpad or Notepad)
• Special format Image files are usually associated with special software e.g. Erdas Imagine uses a special format .IMG (not the same as Idrisi’s .IMG though!)
Data Formats/File Extensions
• These files and file formats in ArcView come together with the .shp (map)
• They are: .shx (header file); .dbf (database file containing the associated table) (sometimes .sbx and .sbn also) Note: must be kept together whenever saved to disk or CD
• Image or Raster files come in many formats. The most common for GIS are: .TIF (Tagged Image File); .JPG (JPEG - Joint Expert Photographic Group; and GeoTIFF (a .TIF with map co-ordinates)
• JPGs (or JPEGs) can also have co-ordinates in a WORLD FILE (text file. World Files contain reference co-ordinates. These files can be opened and viewed in a text editor such as MS Wordpad or Notepad)
• Special format Image files are usually associated with special software e.g. Erdas Imagine uses a special format .IMG (not the same as Idrisi’s .IMG though!)
Data Formats / File Extensions
• Many other data formats other than map and images are also supported by most GIS
• Grid files (often as ASCII .TXT (textfiles) (American Standard Code for Information Interchange
• Spreadsheets and Databases (.XLS - MS-Excel; .DBF - DBASE; .DBF - MS-Access)
• Also, NOTE in the UK, the Ordnance Survey (OS) uses its own format: .NTF (National Transfer Format). Few GIS can read this directly.
• ESRI’s Map Manager (in the Geography Folder) must be used to convert OS map files to .SHP for input to ArcView
• OS Mastermap data comes in the GML (Geography Markup Language) format
Data Formats / File Extensions
• The Image formats are accessed in ArcView by switching on ArcView Extensions: JPG, TIF and IMG and changing from Feature data to Image Data
• In other software you may need to use IMPORT functions/utilities• There are many other image file formats that are not directly used in
GIS e.g. .BMP, .GIF, .PNG • If image files do not come in the correct format for a GIS to use, then
you may have to use UTILITY software to convert to the desired format e.g. Paintshop Pro, Fireworks
• CAD files can also be imported: the most common is the Data Exchange Format (.DXF)
• ArcView (and other GIS) can use DXF by switching on the .DXF extension
Online Data Sources
UK – Raster Map Data
•Landmap: http://www.landmap.ac.uk/
•Landsat: http://www.landsat.org/
•Landsat: http://landsat.gsfc.nasa.gov/
•Landsat: http://landsat.usgs.gov/
•SPOT: http://www.spotimage.fr/
•ASTER: http://asterweb.jpl.nasa.gov/