Assignment 1
Homework # 3 This Homework Assignment is to be completed individually.
Objectives: - Gain experience with more ArcGIS data types o Import a shapefile to a geodatabase o Work with geodatabases, shapefiles, and raster data o Create simple map displaying data with useful symbology Register (Geo-reference) a scanned image o Create control points o Update geo-referencing Digitize features o Utilize snapping, create new feature
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I. Exporting a shapefile to a geodatabase.
The projected river dataset will eventually go into the City's geodatabase. You'll export the dataset to a feature class in the WaterProject geodatabase now, so it will be in the right format to be copied into the City's geodatabase later. 1. Open ArcCatalog. 2. In the Catalog tree under the project folder in your U drive, navigate to the Homework_Project/project/City_share folder, right-click river02prj, point to Export, and click To Geodatabase (single).
2. Click the Browse button next to the Output Location box and navigate to the Homework_Project/project folder in your U drive.
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3. Select WaterProject.mdb and click Add. 4. Click in the Output Feature Class Name box and type "river03exp" to indicate that this is the third version of the river and it has been exported to the geodatabase. 5. Click OK. ArcGIS shows the progress of the export operation. When it finishes, navigate to the WaterProject geodatabase and double-click to display its contents. The river03exp feature class is listed (you may need to refresh the tree by clicking View and clicking Refresh to see it).
II. Digitizing the historic park.
You need to add the new historic park to the parks layer so you can include it in the buffer around parks you'll create during the analysis. You'll digitize the new park into the copy of the parks feature class in the WaterProject geodatabase. After opening a new map in which to do the digitizing, you'll register the scanned image to the streets layer. You'll then digitize the park boundary and add the attributes for the new park. You'll need to add four datasets to the map: the existing parks feature class that you'll be adding the new park to; the scanned image of the park boundary (stored as a TIFF file), which you'll use as a guide while digitizing; the streets layer that you'll use to register the scanned image; and the parcel_2 coverage that you'll use to snap the park boundary to since the boundary aligns with the parcel boundaries. A. Open a new map. 1. Open ArcMap. Choose a new empty map and click OK. 2. Set Relative Pathways (File>Map Properties>Data Source Options)
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2. Open ArcCatalog if not already open, navigate to the WaterProject geodatabases (under Homework_Project/project) and expand it as well as the Parks Feature Dataset. 3. Click and drag parks_polygon onto the map in ArcMap. 4. Add the parcel_2 coverage to the map by opening the City_share\land folder in ArcCatalog, clicking parcel_2, and dragging it onto the map. 5. Click the Full Extent button on the Tools toolbar to see all of both layers. 6. Add the streets layer to the map by opening the City_layers folder, clicking streets, and dragging it onto the map. (Alert me if your streets layer doesn't show up; you may need to repeat step II. E. 1-6 from Homework #2 and then overwrite the old files when prompted whether to do so, then try adding the layer. If your streets layer does show up, then ignore this message.) 7. Now open the City_share\image folder and click and drag historic onto the map. You get a warning that the layer is missing spatial reference information---its coordinate system is undefined. That's OK because you'll be registering the image interactively to place it in the correct geographic space. Click OK to close the warning message. You'll notice that the image is not displayed even though it has been added to the map. That's because it's in scanner units (inches) rather than in geographic coordinates. 8. Click the Full Extent button on the Tools toolbar. When the map redraws, you can see the City data layers as a small dot in the upper center of the view. The scanned image is actually drawn in the lower center, but it's too small to even see. You need to register the image so it is in the same geographic space as the streets, parcels, and parks. 9. Right-click historic.tif in the ArcMap table of contents and click Zoom To Layer. Now you can see the image. Before registering the image, save the map in case you need to stop or take a break during the process.
4 10. Click File. Click Save, and save in your U: drive under Homework_Project, naming the map "parks". B. Find the park area on the streets layer. You'll register the image to the streets by interactively adding links between the image and the streets layer---first pointing at a registration mark on the image, then at the corresponding intersection on the streets layer. You'll need to find the area on the streets layer corresponding to the area covered by the image. To make this easy to do, you'll first open an overview window, so you'll be able to see the image and the streets at the same time. 1. Click Window and click Overview.
A small window appears showing the image. Now you can find the park area on the streets layer and zoom to it. The image has several streets marked on it in the vicinity of the park including Robin Lane, Peacock Lane, and Sparrow Drive. You can search for one of these on the streets layer to find the area the park is in. 2. Click the Edit menu and click Find, or use the Find Tool (Binoculars) in the toolbar. 3. In the Find box type "Peacock". 4. Click the In dropdown arrow and click streets. 5. Click the In fields button under search, click the dropdown arrow, and click NAME. 6. Click Find. Peacock appears in the list of features that have been found. 7. Right-click Peacock and click Zoom to feature(s). The map displays the area that includes Peacock Lane. The overview window still displays the image. You may want to enlarge the overview window so it's easier to see the image---simply click and drag one of the corners of the window. You may also want to move the overview window to make it easier to see the streets. 8. Click Cancel to close the Find dialog box.
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To make sure you're in the right area, label the streets. 9. In the table of contents, right-click streets and Label Features if they're not already labeled. 10. Use the Zoom In tool, Zoom Out tool, and the Pan tool on the Tools toolbar to zoom to the four street intersections that correspond to the same intersections shown on the scanned image. Basically, you want roughly the same area shown on the image to be shown in ArcMap using the streets polygon. 11. Close the overview window. Now the display is zoomed to the area corresponding to the image. 12. You won't need to display parcel_2 for the next set of steps, so uncheck layer the to make it easier to see the streets. C. Register the scanned image. Now you're ready to register the image to the streets layer. You'll do this by adding links between the control points on the image and the corresponding street intersections on the streets layer. This is known as georeferencing. 1. Click the View menu, point to Toolbars, and click Georeferencing. 2. Click the Layer dropdown arrow in the Georeferencing toolbar and click historic.tif if it's not already selected. 3. Click the Georeferencing dropdown arrow and click Fit To Display.
ArcMap scales the image to fit in the current window. Since the window is currently zoomed to the four street intersections that match the registration marks on the image, the streets and the image are displayed at approximately the same scale. You can see, though, that the control points aren't located exactly at the intersections. You'll add four links to register the image. To make it easier, you'll use a magnifier window. You can add control points within the magnifier window.
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4. Click Window and click Magnifier. A small window appears with a default magnification of 400 percent. 5. Click the Add Control Points button on the Georeferencing toolbar.
The cursor turns into a crosshair. 6. Drag and center the magnifier window over the registration mark in the upper right, labeled 602. If necessary, reposition the window so you can see both the registration mark and the corresponding street intersection (Robin and Sparrow) within the window. You may need to make the magnification window larger by clicking on one of the corners of the window and dragging to expand it. If it's too difficult to see both the registration mark and the street intersection, just use the Zoom In tool. Note that the registration mark and intersection will likely be in slightly different positions on your map. 7. Center the cursor over the registration mark and click. A green control point is added to the image. Move the cursor away from the control point but don't click again. A line stretches from the control point as you move the cursor. This is the link---you'll connect the other end of it to the corresponding street intersection. 8. Center the cursor over the intersection of Robin and Sparrow on the streets layer (you can see the link stretch as you do this) and click. You've added the other end of the link. The second control point is shown as a red crosshair. 9. Click the View Link Table button on the Georeferencing toolbar.
For each link, the table lists the x- and y-coordinates for the source (the scanned image) and the corresponding coordinates for the map (the streets layer). If you make a mistake and need to delete a link, select it and click the Delete button, which looks like the letter x. 10. Close the Link Table. Now you'll add the other two links.
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11. Drag and center the magnifier window over the registration mark in the lower left, labeled 610, and release the mouse button. 12. Center the cursor over the registration mark and click. 13. Center the cursor over the intersection and click to add the second control point. You may have to move the magnification window to see the intersection. The image adjusts slightly. Now add the third link in the same manner. 14. Drag the magnifier window over the registration mark in the lower right, labeled 473. 15. Finish setting control points for 473 and for 601. Make sure that you have the correct streets lined up! Both the historic.tif image and the streets should be labeled so you can make sure that you have the correct ones. If you mess up, you can simply delete one control point, or completely re-register the image. Now the control points match up pretty closely with the intersections. 16. Click the Georeferencing dropdown arrow and click Update Georeferencing to save the new registration.
You don't need the control points anymore. If we were using this layer for analysis and not just for digitizing a quick polygon, we would need to rectify it as well, then define the projection. 17. Click the Georeferencing dropdown arrow and click Delete Control Points. Then close th...