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Introduction to Geographic Information System

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1 Introduction to Geographic Information System
Qian Yu Department of Geosciences promote the teaching of Earth Science in the science curriculum . Visualization is an important part in the teaching of Earth Sci, especially for the middle and high school. Geographic information system is a computer system which can help you to link the earth sci knowledge to geographic observation, map, Advanced technology, highly related to people’s life, most useful. Through this section, you will find how many you have heard about GIS? How many of you heard about GPS? GIS and GPS difference. GIS is a process, GPS is data collection.

2 Outline What is GIS? GIS data format Understanding scale
Global Positioning System GIS application MassGIS data MassGIS data viewer Google Earth Academic definition. Have sensed GIS, How GIS saved in the computer. Scale, same region but different scale. Where you download data? Software, you can use it, it is free. Basic function of GIS software. Internet GIS, Google earth, how many of you heard about Google earth. The same

3 Digitizing Our World Two types of information: Location Attribute
Location Information: Where is it? Attribute Information: What is it? Species: Oak Height: 15m Age: 75 Yrs Our world can be digitized to view and to study on computers. Every element of our world, can be described with two types of information, location and its property or attribute. Location: coordinate information (latitude and longitude) Attribute: descriptive information Let’s take this tree as an example... This tree can be distinguished from other objects with location - at 51oN and 112oW. This tree can be further described with “attribute information”. This is an oak tree, it is 15m high and it is 75 years old. GIS is used to handle digital world with location and attribute information. To save both the spatial location and attribute, we need GIS. 51°N, 112°W After: ESRI, 2001

4 What is GIS? GI System: A GIS is an immensely powerful computer mapping and analysis system. It links geographic locations with information about them so you can create maps and analyze information in new ways. Techniques for acquisition, storage, manipulation, analysis, and display of spatial data. GI Science: research with GIS (Applied Science) With the example just given, it might make us easier to understand the written definition for GIS GIS is the abbreviation for both Geographic information systems and Geographic information science. GI Systems is an computer mapping and analysis system, which links geographic locations with information about them. This system could allow you acquire, save, manipulate, analyze and display spatial data. GI Science is about the GIS application for scientific research In future, we refer GIS as GI System. we use GIS applications to refer GI Science

5 Subsystems of GIS Input System digitizing, scanning, GPS
Database Management System Geographic Analysis System Output System Software Tools Database + GIS Results or Simplification Abstraction The real world How does GIS work? GIS consists of four subsystems. input system , database management system, geographic analysis system and output system. The real world is abstracted and simplified through input system. The digitized information (data) is saved in spatial database management system allowing for retrieving and storing access. Geographic analysis system is the core of a GIS system. It provides a large amount tools for data analysis. Those tools can be further expanded with users demand. Data output system brings data to users through web browser, printer in the format of maps and so on. Learning the principles and operations of these four subsystems are the part of this course.

6 GIS data format - Geographic Data Representation
Raster Vector 1 2 3 4 5 6 7 8 9 5 4 3 2 1 X-Axis Y-Axis Pt 1 Poly 1 Poly 2 Line 1 1 3 2 4 Point Line Polygon GIS represents our world elements (the geographic data) in two formats: Raster and vector. Raster is based on a regular tessellation of a surface into pixels or grid cells (image is in the raster format. Each cell are filled with an attribute values. vector is constructed from geometric primitives: point, line and polygon as a logical structure. A point could be a tree, or a house; a line feature could be a road, or river; the polygon features could be land parcels, lakes. The attribute or descriptive information are usually associated with those primitives. 1 - River 2 - Pine 3 - Fir 4 - House Pt 1 Building Owner Line 1 House Length Poly 1 Fir Area Poly 2 Pine

7 Scale Scale: the ratio of the distance on a map to that on the ground between the same two points, in the same units. Three way to express the scale of a map Representative fraction 1:1,000,000 Statement scale One millimeter to one kilometer Bar scale Larger scale (ratio) maps show more detail. GIS data can be displayed at any scale, but GIS data should not be displayed beyond the accuracy at which the data was developed. For example, if contour lines compiled at the very small scale of 1:250,000 are displayed at 1:25,000 with water resource features developed at much larger scale of 1:25,000, contour lines will appear to cross lakes and ponds --an obvious error.  Scale is represented on this web site as a ratio, such as 1:25,000 (read "one-to-25,000") which means one inch measured on the map equals 25,000 inches in the real world). Scales are relative: the term "large scale" describes data with more detail than "small scale" data. For example, data at 1:25,000 is at a smaller scale than data at 1:5,000, but at a larger scale than data at 1:100,000. In other words, the larger the ratio, the smaller the map scale. Therefore, a map of the world would have a very small scale, whereas a map of a town center will have a large scale. disregarding the scale of the source material can create problems.

8 More detail 1:250,000 smaller scale 1:100,000 mid-scale
1:62,500 1:24,000 larger scale 1:24,000

9 Global Positioning System
GPS a global satellite based radio-navigation system/technology, consisting of 24 orbiting satellites at an altitude of 20,000 km in space, in six different orbital paths/plane and their ground stations. 12 hours return interval for each satellite (2 complete orbits around the Earth in less than 24 hours). Functioning satellite GPS systems NAVSTAR

10 GPS components Satellite segment Control segment User segment
Tracking, communications, data gathering, integration, analysis… User segment GPS receivers

11 Why is GIS important? Overlay visualization or modeling Map production
Integration data sources Spatial analysis and modeling Exploration and prediction Why is GIS important? In another words, how do we use GIS? One way of using GIS is to visualize the different objects in multiple layers. Each layer contains one type of objects such as rivers, soil, vegetation or topography. Then overlay of these layers we can discover why vegetation is in a better condition in one location using color, is it soil type? Or distance to river? Or flat topography? Through overlay, we can see the relative spatial relationship between layers in terms of size, distance, distribution and orientation. If these visualized information can be described automatically with computer functions in GIS, it is called modeling The visual assessment requires data integration, map production, and modeling is for spatial analysis and prediction In this class, we will cover more map presentation and basic concepts on modeling using available functions Why we need GIS? GIS is an important technology because "Everything Happens Somewhere". GIS help us to integrate the different data sources, produce map and conduct spatial analysis and modeling, for example here, base map, district, and road network, terrain models could assist urban planning. In addition, the future happenings or change could be predicted. In 1854, a major cholera outbreak in London had already taken nearly six hundred lives. Early theories blamed the infection on mists and miasmas. Dr. John Snow believed that if mists and miasmas caused cholera, the cases should be uniformly distributed along streets. By plotting each known cholera case on a street map of Soho district (where the outbreak took place), Snow could see that the cases occurred almost entirely among those who lived near the Broad Street water pump. This pump belonged to a company, which drew water polluted with London sewage from the lower Thames River.

12 GIS Application Daily life Cartography Environmental management
3D visualization Modeling The application of GIS is limited only by the imagination of those who use it. - Jack Dangermond In addition to fun and daily usages, GIS is a very powerful professional skills. Nowadays, it is very difficult to find something that don’t need GIS. It has been widely used in management, industry, and research (social and nature). As Jack Dangermond, the founder of the largest GIS software company ESRI , said, the application of GIS is limited only by the imagination of those who use it. Before finishing the class, Let’s take a look several examples more than having fun.

13 3-D Topography Pioneer Valley
Why we study GIS? First of all, I’d say, it is for fun. Look, before my visit to this campus, I spent about 15 minutes and downloaded digital elevation data for the campus location. I displayed the data in 3-D format with color indicating surface relief. (light color high elevation and dark low elevation) and I locate the campus by zip code. Is it a fun? I enjoy this. It is a color poster if we put the picture of the campus buildings. Where are we? It must be one of building here. This is the 3-D digital elevation model. Any of you could guess where is it? Yes, pioneer valley, Ok, then, Where we are?

14 Our daily life need GIS Driving direction Locating a store
GIS for showing where you are and the best route from A to B Locating a store GIS for mapping shops near you The second reason for studying GIS is the need in daily life. The two examples that I displayed in this slide might have been experienced by many of you. One is driving direction. Before traveling, you might use yahoo or mapquest to find routes to get B from A. Even when an accident happened, you can find where you are in map and the best alternative route. When you visiting a place and want to buy something in a particular store, you might visit their website and input your zip code. The GIS system will provide you a map with store locations near you. GIS become common knowledge for understanding daily usage.

15 Combing Data From Many Sources

16 3-D Display View large data sets seamlessly 3D mine with well data
3-D Virtual Model for Urban Planning 3D urban

17 Hydrodynamic Modeling: Downstream Flooding
The digital elevation model includes the building structures and land surface. The hydrological models can use these information to estimate where has risk for flooding, if the reservoir broken. GIS can be used to guide for emergency response. These maps present the results of a MIKE21 DHI Water & Environment simulation of a facility breach and subsequent downstream flooding. A series of 126 CAD drawings was processed to extract contour elevations, building structures, and heights. This process was accomplished using ArcObjects Visual Basic for Applications programming directly in ArcMap. Maps such as this are used to assist downstream agencies in emergency action planning in the event of a facility failure. Sacramento, California, USA (From: U.S. Bureau of Reclamation)

18 GIS Data in MassGIS Base Map Data Environmental Data
Vector (point/line/area) Features such as roads, streams, and political boundaries--relatively permanent, widely used features. In shape file or coverage Raster (image data) Black & White Digital Orthophotos, Scanned USGS Quads, and Coastal Color Orthophotos, Available in Tiff and MrSID formats. Environmental Data Developed, maintained and updated by EOEA and its agencies for the purpose of enforcing environmental regulations or in support of various types of environmental analysis. MassGIS data can be divided into two broad categories: base map data and environmental data. these data have been developed at a variety of scales. The data may also be categorized further, based on types of geographic features, such as infrastructure, physical resources, and political boundaries. This page describes the two broad categories. Many of the base map datalayers maintained by MassGIS have been derived from U.S. Geological Survey data and represent many of the feature types found on USGS topographic maps. More recently developed data were derived from the digital orthophotos providing improved basemap accuracy. MrSID is an acronym for Multi-resolution Seamless Image Database, a powerful wavelet-based image compressor, viewer and file format for massive raster images that enables instantaneous viewing and manipulation of images locally and over networks while maintaining maximum image quality. Features include unprecedented compression ratios while maintaining highest image quality, true multiple resolutions, selective decompression, seamless mosaicking and browsing.

19 MassGIS Runtime Data Viewer
Stand-alone, "light," or scaled-down version of ArcView GIS 3.1.1 With much of the map-making functionality Function: Display all the MassGIS data Change symbolization of the data and add annotation to the map Create a map layout with map elements such as a scale bar, north arrow, legend and title Conduct data query and analysis

20 Google Earth Client software of web GIS service. Function:
The planet's imagery and other geographic information are put on server and your computer retrieves data through internet real-time. Function: Fly from space to your neighborhood. Type in an address and zoom right in. Search for schools, parks, restaurants, and hotels. Get driving directions. Tilt and rotate the view to see 3D terrain and buildings. Save and share your searches and favorites. Even add your own annotations.

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