Introduction to ArcGIS 10.2

Transcription

1 Introduction to ArcGIS 10.2 Francisco Olivera, Ph.D., P.E. Srikanth Koka Lauren Walker Aishwarya Vijaykumar Keri Clary Department of Civil Engineering April 21, 2014 Contents Brief Overview of ArcGIS Goals of the Exercise... 2 Computer and Data Requirements... 2 Procedure Creating Geodatabases, Feature Datasets and Feature Classes Displaying Spatial Datasets in a Map Accessing Attribute Data Selecting Objects of a Geodatabase Table (points, lines and polygons) Making a Chart Consolidating Your Results for Presentation Department of Civil Engineering

2 Brief Overview of ArcGIS 10.2 ArcGIS 10.2 is a geographic information systems (GIS) platform developed by Environmental Systems Research Institute (ESRI). It provides the tools to compile, use, and manage geographic information. It includes comprehensive professional GIS applications that support a number of GIS tasks, including mapping, data compilation, analysis, geodatabase management, and geographic information sharing. The three main components of ArcGIS 10.2 are ArcCatalog, ArcMap, and ArcToolBox. ArcCatalog is used for browsing for maps and spatial data, exploring spatial data, viewing and creating metadata, and managing spatial data. ArcMap is used for visualizing spatial data, performing spatial analysis, and creating maps to show the results of your work. ArcToolBox is a wizard that contains all the available ArcGIS 10.2 tools, including data conversion tools, data management tools, and limited data analysis tools. All parts of the ArcGIS system have integrated online functionality, and the system includes online maps and geographic information. Goals of the Exercise To introduce you to ArcGIS: ArcCatalog and ArcMap. Computer and Data Requirements To complete this exercise, you will need ArcGIS You will be working with the following spatial datasets: a polygon shapefile of the Counties of Texas called Counties and a point shapefile of pan evaporation stations called Evap. These shapefiles consist of seven files each evap.dbf, evap.prj, evap.sbn, evap.sbx, evap.shp, evap.shp.xml, evap.shx, Counties.dbf, Counties.prj, Counties.sbn, Counties.sbx, Counties.shp, Counties.shp.xml, and Counties.shx. Download the Ex1Data.zip file containing the data, which is in the same folder where this document is located. Unzip or extract it and save the files to a working directory on your computer. Make sure to remember the location of these files so that you can access them later. Procedure Department of Civil Engineering 2

3 Note that the following procedure is a general outline that can be followed to complete this lesson. However, you are encouraged to experiment with the program and be creative. 1. Creating Geodatabases, Feature Datasets and Feature Classes A geodatabase is a relational database that stores geographic information. In turn, a relational database is a collection of tables logically associated to each other by common key attributes. A geodatabase can be considered a relational database that can store geographic information because, besides storing numbers or strings in the attribute columns, it can store features or geometric objects (i.e., polygons, lines or points) with defined shape and location. A geodatabase has an extension mdb. Tables in a geodatabase are called object classes. A feature class is a special type of object class that contains features. Thus, a feature class is a collection of features that have the same behavior and the same set of attributes. Note that feature classes do not need to be stored inside a feature dataset, and can be stored as stand-alone classes in the geodatabase. A feature dataset is a collection of feature classes that share the same spatial reference. The spatial reference describes both the projection and extent for a feature class in the geodatabase. a. Creating a new geodatabase: (1) Open ArcCatalog. (2) On the left panel, search for the folder where you want to create your geodatabase. If the folder is not displayed here, right click on Folder Connections in the left panel and select Connect Folder. Select the appropriate folder. (3) Right click on the folder name or icon. (4) Click New/Personal Geodatabase; a new geodatabase called New Personal Geodatabase.mdb (represented by a cylinder-shaped icon) will be created. (5) Overwrite the name of the geodatabase with Ex1Data (the geodatabase will keep its file extension.mdb regardless of whether or not you include it in the name). Department of Civil Engineering 3

4 b. Adding data to the Ex1Data.mdb geodatabase within a feature dataset (1) In ArcCatalog, right click on the name or icon of Ex1Data.mdb. (2) Click New/Feature Dataset (3) Name the new dataset Texas and click Next. (4) Choose the coordinate system for this dataset in this window. Click the Add Coordinate System button and click Import. Browse for the shapefile Counties and click Add. Click Next twice and then Finish. This gives your Feature Dataset the spatial extent and projection of Counties. Data should not be added to a feature dataset before its spatial extent and projection are defined. (5) Right-click on the name or icon of Ex1Data.mdb\Texas (6) Click Import/Feature Class(multiple) (7) In the Feature Class to Geodatabase (multiple) window, click on the open folder button next to Input Features. Locate and add the Counties and Evap shapefiles. Click OK. After creating the geodatabase, the feature dataset, and the feature classes, the ArcCatalog tree in the left pane should look like this when all the + boxes are clicked: Department of Civil Engineering 4

5 Note that the feature classes Counties and Evap could have been created outside the feature dataset Texas; but, because they share the same spatial extent, they were grouped together. In ArcCatalog, you can toggle the right panel display between a file tree (Contents tab), a data view (Preview tab), and a metadata document (Description tab). The preview option allows you to display the feature class shapes and table, by selecting geography or table at the bottom of the panel. You may now close the ArcCatalog program. 2. Displaying Spatial Datasets in a Map In ArcMap, a layer consists of a reference to a spatial dataset (such as a feature class, shapefile or coverage) and a definition of how to display it (legend colors, line thickness, etc.), and a map is a graphical representation of geographic information. The left panel in the ArcMap window shows the Table of Contents, and the right panel is the Display Window. The Table of Contents lists layers and the Display Window displays maps. A. Displaying the spatial data of the Texas feature dataset in a map (1) Open ArcMap and then click on the Add Data button in the toolbar under the menu bar. Alternatively, click on File/Add Data/Add Data from the dropdown menu. (2) Browse to the feature dataset Texas and click Add. You can also add each feature class in the Texas feature dataset separately. Department of Civil Engineering 5

6 Note that the Table of Contents lists the layers corresponding to the two feature classes of the Texas feature dataset that you just added, while the Display Window displays the map with the corresponding spatial data (i.e., Texas counties and evaporation stations). (3) Save your work in a Map Document. Click File/Save, navigate to your working directory, and name the file GISWREx1 (the file will automatically be assigned the extension mxd). B. Modifying the display of the Counties layer in the map (1) Right click on the Counties layer name and click the Properties menu button. (2) Click the Symbology tab and then click on the button showing the symbol; the Symbol Selector window opens. Make your selections for the Fill Color, the Outline Width, and the Outline Color, and click OK. Department of Civil Engineering 6

7 (3) Click OK again. Follow the same procedure to modify the display of the Evap layer. The new map hopefully looks better than the original one. 3. Accessing Attribute Data Numerical and text information stored in the fields of the geodatabase tables is called attribute data. A. At a specific location in ArcMap (1) In ArcMap, make the layers Evap and Counties (assuming you want to retrieve information of both layers) visible and then click on the Identify tool in the Tools toolbar. If this toolbar is not displayed, turn it on by going to Customize/Toolbars/Tools. (2) Click the location on the map in which you are interested. (3) The Identify Results window will open, in which the attributes of only the top most layer are displayed. (4) To display the attributes of the features of both layers at a location in the map, in the Identify window, select All layers in the Identify from: dropdown list. (5) Start clicking on locations that interest you on the map. In the figure, attribute data for the evaporation station in Lake Colorado City and Mitchell county have been retrieved; however, because Mitchell county is highlighted, the bottom panel of the Identify window displays attribute data of the evaporation station. You have to highlight the area number under Counties to get the attribute data for the specific. Department of Civil Engineering 7

8 B. Of an entire layer (1) In ArcMap, right click on the Evap layer name in the Table of Contents. (2) Click Open Attribute Table. This tables contains the attribute data of the layer and contains a field called Shape. The Shape field displays the words Point, Line or Polygon, but really stores a geometric object with the shape and location of a point, line, or polygon. Department of Civil Engineering 8

9 Note that record number 17 corresponds to the Lake Colorado City evaporation station. All attribute data shown in the table is the same as previously retrieved using the Identify tool. C. Calculating the statistics of a field (1) In ArcMap, right-click on the header of the ANN_VAL field in the attribute table for Evap (ANN_VAL contains annual evaporation data). (2) Select Statistics, and a statistics chart is displayed in a separate window. You can change the field for which statistics are calculated in the Statistics of Evap window. (3) Close the attribute table and statistics window when you finish looking at them. 4. Selecting Objects of a Geodatabase Table (points, lines and polygons) Selecting objects of a geodatabase table refers to identifying a subset of objects in the geodatabase table for a specific purpose. Object selection can be made from a map by identifying the geometric shape or from an attribute table by identifying the record. Regardless Department of Civil Engineering 9

10 of how you select an object, both the shape in the map and the record in the attribute table will be selected when you select either one. A. Selecting an object from the map (1) In ArcMap, right click on the Counties layer, and then click Selection/Make This The Only Selectable Layer. This allows you to only select features within the Counties layer. (2) Click on the Select Features tool in the Tools toolbar. In the display window, click on the Counties polygon(s) you want to select. To select more than one object, press and hold the Shift key and while you click on additional objects. Selected objects are displayed with a light blue outline, although the color might change depending on your settings (to change the settings, click Selection/Selection Options/Selection Tools Settings). The corresponding attribute table records will also have been selected. You can verify this by opening the Counties attribute table and checking whether they are highlighted. Department of Civil Engineering 10

11 (3) To clear your selection, right-click on the layer name, and choose Selection/Clear Selected Features. B. Selecting an object from the attribute table (1) In ArcMap, click on the layer name Counties in the Table of Contents and select Open Attribute Table. (2) In the Attribute Table, click on the square to the left of the records you want to select. To select more than one record, press the Ctrl key and hold it down while you click on additional records. Selected records are displayed with a light blue background, although the color might change depending on your settings. The corresponding objects in the map have also been selected. You can verify this by returning to the map window. Department of Civil Engineering 11

12 (3) To clear your selection, click on the Options button in the Attribute Table window, and choose Clear Selection. Close the table. 5. Making a Chart A chart of one or more records selected from a geodatabase table can be plotted. Follow the directions below to plot the monthly evaporation of one or more stations. (1) In ArcMap, select one or more evaporation stations from the Evap layer. If you want to select features directly from the map, make sure to define the appropriate layer (in this case, the Evap layer) as a selectable layer by clicking on Selection/Make This The Only Selectable Layer menu. Otherwise, select from the attributes table as described previously. (2) Open the attribute table of the Evap layer. In the Attribute Table for Evap, click on the Options button and then Create Graph... In the Create Graph wizard, select Vertical Bar as the Graph type and Evap as the Layer/Table. Select the field JAN_VAL from the dropdown menu for Value field. Select Custom under Color. Click Next. Click the radio button next to Show only selected features/records on the graph. Now, click Back. Click on Add/New Series and select the field FEB_VAL under the Value field and change the Color to Custom. Repeat for MAR_VAL to DEC_VAL. Set X Label Field as STAT_NAME. You can rename the Series by double clicking on the tabs containing their names. Click Next. Overwrite the Title field with Evaporation, browse through the Axis properties, make the necessary changes. (Once you click the Finish button, you cannot make changes to your graph. If you close this window, you will have to create your graph from scratch). Click Finish. You will obtain a graph similar to the one shown below. Do not close this window; this graph is not saved anywhere and will be lost if you close the window. Department of Civil Engineering 12

13 Note that the charting capabilities of ArcMap are not as developed as those in other applications. To prepare charts that are more complex you can export your tabular data to other applications. 6. Consolidating Your Results for Presentation To consolidate a map of Texas Counties with evaporation stations with the graph that you created before on a single sheet of paper, follow the directions. (1) In ArcMap, change the format of the display window from Data View to Layout View by clicking on Layout View in the View dropdown menu. (2) Reduce the size of the data frame (i.e., rectangle where the spatial data is contained), to make room for the graph, by clicking on the page and moving its handlers. (3) Right click on the graph and select Add to Layout. You can move and resize the graph as necessary. Department of Civil Engineering 13

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15 Your final map should look like this: These materials may be used for research and educational purposes only. Please credit the authors and the Department of Civil Engineering,. All commercial rights reserved. Copyright 2014:. Department of Civil Engineering 15