Week 1: Introduction to GIS UP206A | PP191A | PP224A Yoh Kawano

What is GIS A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts. A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared. GIS technology can be integrated into any enterprise information system framework. 2

So…. What can you do with gis?

Map Where Things Are Mapping where things are lets you find places that have the features you're looking for, and to see where to take action. Find a feature—People use maps to see where or what an individual feature is. Finding patterns—Looking at the distribution of features on the map instead of just an individual feature, you can see patterns emerge. Maps of the locations of earthquake shaking hazards are essential to creating and updating building codes used in the United States. Online, interactive earthquake maps, as well as seismicity and fault data, are available at earthquake.usgs.gov. 

Map Quantities People map quantities, like where the most and least are, to find places that meet their criteria and take action, or to see the relationships between places. This gives an additional level of information beyond simply mapping the locations of features. This map shows the number of children under 18 per clinically active pediatrician for a particular study area. It was created by the Center for the Evaluative Clinical Sciences at Dartmouth Medical School as part of an effort to develop a national U.S. database of primary care resources and health services. For example, a catalog company selling children's clothes would want to find ZIP Codes not only around their store, but those ZIP Codes with many young families with relatively high income. Or, public health officials might not only want to map physicians, but also map the numbers of physicians per 1,000 people in each census tract to see which areas are adequately served, and which are not.

Map Densities While you can see concentrations by simply mapping the locations of features, in areas with many features it may be difficult to see which areas have a higher concentration than others. A density map lets you measure the number of features using a uniform areal unit, such as acres or square miles, so you can clearly see the distribution. Mapping density is especially useful when mapping areas, such as census tracts or counties, which vary greatly in size. On maps showing the number of people per census tract, the larger tracts might have more people than smaller ones. But some smaller tracts might have more people per square mile—a higher density.

Find What's Inside Use GIS to monitor what's happening and to take specific action by mapping what's inside a specific area. For example, a district attorney would monitor drug-related arrests to find out if an arrest is within 1,000 feet of a school--if so, stiffer penalties apply. This image from The Sanborn Map Company, Inc., shows a geoprocessed sample explosion radius around an area in California. Each separate zone represents 1/4-mile, the outermost perimeter being 1 mile away from the source.

Find What's Nearby Find out what's occurring within a set distance of a feature by mapping what's nearby. The Pacific Disaster Center has developed and applied a Vulnerability-Exposure-Sensitivity-Resilience model to map people and facilities (what's nearby) exposed to flood risk in the Lower Mekong River Basin (the feature).

Map Change Map the change in an area to anticipate future conditions, decide on a course of action, or to evaluate the results of an action or policy. By mapping where and how things move over a period of time, you can gain insight into how they behave. For example, a meteorologist might study the paths of hurricanes to predict where and when they might occur in the future. Map change to anticipate future needs. For example, a police chief might study how crime patterns change from month to month to help decide where officers should be assigned. Map conditions before and after an action or event to see the impact. A retail analyst might map the change in store sales before and after a regional ad campaign to see where the ads were most effective. These images are from a poster titled "Losing Cape Cod," which is distributed by the Woods Hole Research Center in Woods Hole, Massachusetts. The poster shows the severe change in land use on Cape Cod since 1951. The image on the left shows the town of Barnstable in 1951 and the image on the right shows Barnstable in 1999.

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some lingo you need to know… 12

Data Types Raster Data represented by pixels with values, creating a grid Vector Data stored as points, lines, and polygons Uses less memory than raster format Does not loose positional accuracy 13

Feature Types POINTS LINES POLYGONS Identifies a place at a discrete location. Each point is located using a single X,Y coordinate pair. LINES Used to represent linear entities, such as roads, rivers,etc., Lines (also known as arcs) are made of connected strings of line segments. Vertex/Nodes--the more, the more precise POLYGONS Shape files representing areas 14

Features and their representation 15

Creating Maps Level 1

ArcGIS Applications Description: ArcCatalog: Allows the user to easily access and manage geographic data that is stored in folders on local disks or relational databases that are available on the user's network.  Data can be copied, moved, deleted, and quickly viewed before it is added to a map.  In addition, metadata can be either read or created using this ArcGIS application. ArcMap: Allows the user to display and query maps, create quality hardcopy maps and perform many spatial analysis tasks. ArcMap provides an easy transition from viewing a map to editing its spatial features.

Viewing Data in ArcCatalog The data can be previewed by navigating to its location in the catalog tree. If the folder or network drive that contains the user's data is not shown in the existing catalog tree, the Connect to Folder button can be used.

As well as previewing the geography of a data set, the user can also preview the attributes. At the bottom of the catalog display, there is a preview drop-down list. This allows the user to view either the geography or the associated attribute table for the data layer. In addition to previewing the geography and the attribute table of a data layer, the user can view or create metadata. By clicking on the Metadata tab in the catalog display, technical information about the data set (such as its coordinate system, its spatial extent, description of its attributes, and descriptive information about when and how the data was created) can be obtained.

Viewing Data in ArcMap The ArcMap application window consists of a map display for viewing spatial data, a table of contents for listing the layers shown in the display and a variety of toolbars for working with data.

Drag and Drop Simply click the name of the data layer from the ArcCatalog data tree, and drag it anywhere within the ArcMap display.

Order is Important When multiple data layers are visible, the user can drag a layer to the top of the table of contents in order to place that data layer on top of all of the other layers. In the following example the Interstate Highway layer was moved to the top of the table of contents in order to make data visible within the map display window.

The Main Toolbar The ArcMap Tools toolbar can be used to do a variety of operations. The toolbar may initially be oriented vertically, but its orientation can be changed by dragging one of its corners. Additionally, it can be moved so that its location is next to the standard toolbar.

The Attribute Table In a GIS, a feature on a map may be associated with a great deal of information. This information is stored in an attribute table. A layer's attribute table contains a row (or record) for every feature in the layer and a column (or field) for every attribute or category of information.

The Attribute Table Records, as well as fields, can be highlighted. When a record is highlighted in a table, its corresponding feature is highlighted on a map. A highlighted record or feature is said to be selected. The user can highlight a record in a table by clicking on the left edge of the record of interest in the table. Once the record is selected, the corresponding feature will be selected in the map display.

Saving an ArcMap Project Relative Path vs Full Path Why is this important?