Exploring the Power of GIS: Mapping the Future PART2
- 1. GPS (Global Positioning System) • A space based global navigation satellite system, developed by US Defence around 1973. • Useful tool for maps making, way or path marking, tracking, and is widely used throughout the world for research and planning. • GPS provides reliable positioning, navigation (tracking, direction or place finding) and timing services to worldwide users on daily basis. • GPS is consisted of a series of 24 satellites which transmit data, allowing users on earth to mark their location with great accuracy.
- 2. GPS- how it works? • A GPS receiver calculates its position by precisely timing the signals sent by the GPS satellites above on the Earth. Each satellite continuously transmits messages which include the time the message was sent and some additional information. The receiver measures the transit time of each message and computes (calculates) the distance to each satellite. Geometric trilateration is used to combine these distances with the satellites’ locations to obtain the position of the receiver.
- 3. Arc GIS • How data is stored in ArcGIS- geodatabase • Components of ArcGIS- ArcMap, Arc Catalogue and ArcToolbox • Extensions of ArcGIS- Spatial analysist, geostatistical analyst and 3D analyst • Spatial (location) data- Raster and Vector • Raster data includes scanned maps, air photos, elevation layer- most remote sensing data is raster data • Vector data- a layer comprised of individual points, lines, or polygons (roads, rivers or district, country)
- 4. How to start- new or existing map • File • New • Existing • Default geodatabase for this map • Geodatabase icon • Table of contents showing doc’s layers • Add data- File → add data i.e., base map & XY data • Data frame that displays the spatial data- → View → data view → layout view
- 5. Spatial data • The data or information that identifies the geographic location of different features and boundaries • The location data may be, lake, ocean, home or archaeological site • Spatial data refers to the coordinates which is stored and can be used for mapping and analysis • Spatial data uses could be two types
- 6. Metadata • It is commonly known as ‘data about data’. Metadata helps to make data findable and understandable through …………. • Description- info about the content and context of the data • Administrative- information about the file type, most common term and abbreviations, management and preservation processes. • Record all the relevant information need for you and other to retrieve and understand the data in future • Advantages- data discovery, enable interpretation and reuse, clarify ownership and restriction reuse
- 7. What is meta data in GIS? • Metadata is information about data. Similar to a library catalog record, metadata records document the who, what, when, where, how, and why of a data resource. Geospatial metadata describes maps, GIS files, imagery, and other location-based data resources.
- 8. Working with ArcMap • Map documents- providing access to map document (.mxd) properties and methods. A reference to this object is essential for most map scripting operations. File → Map document properties and give the detail • Windows- ArcMap provides three additional map windows to view the spatial data on your map including a Magnifier window, a Viewer window, and an Overview window. When you don't want to adjust your map display but want to see more detail, retain a particular view of an area, or get an overview of an area, open another window. All these windows operate with Data view and not in the Layout view. You can also simultaneously open more than one of these windows.
- 9. Working with ArcMap …………. • Overview- The Overview window uses a box to show the extent of your display view within the total extent of your data. You can use the Overview window to navigate the map in the Data view display. • Magnifier- The Magnifier window works like a magnifying glass: as you pass the window over the data, you see a magnified view of the location under the window. The Magnifier window allows you to see a magnified view of a small area without changing the extent of your data view. You can adjust the magnification by clicking the Percentage drop-down arrow or typing a value.
- 10. Working with ArcMap ……… • Viewer- A Viewer window behaves like an independent view onto the map, and you can use any of the ArcMap interactive tools inside the window. For example, you can zoom and pan to a different part of the map to compare it with what is shown in the main ArcMap window. You can also identify and select features, perform editing, and so on. When you right-click the window, you'll get a menu of useful shortcuts. You can also use the toolbar at the top of the window to navigate your map. The scale for the Viewer window can be specified by clicking the Scale drop-down or typing a value • Help system- help menu → get online and offline help for
- 11. Working with ArcMap……… • Data frames-A data frame is a frame on a map with two-dimensional content that displays layers in the same geographic area. A map may have one or more data frames, e.g., one data frame highlighting a detailed road network, while another one providing an overview of where the detailed road network is within a larger geographic area. It works as INSERT →DATA FRAMES and work in it • Layers- different class features such as sites, places, base map etc. They can be copied, paste, remove and so forth • Symbols and style- right click on the layer in ToC → properties, symbology OR double click on the layer & make changes • Map scales and labelling- insert → legend, north, picture, scale etc • Labelling- on & off → properties → labels