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1 Department of Urban Studies and Planning Spring 2006 Department of Architecture Site and Urban Systems Planning J / 4.255J GIS EXERCISE 2 Objectives: To generate the following maps using ArcGIS Software: Open a DTM Surface (TIN - Triangulated Irregular Network) Contours Slopes Aspect Hillshade Determine Line of Sight Output File as Map or Animation STEP 1: PREPERATION 1. All files for this exercise are located in Open the DTM folder and please copy the following files to your home directory: dtm dtm dtm dtm 2. ArcMap and ArcScene take a long time to load so we will open them now and minimize them for later use. Go to START>PROGRAMS>ARCGIS> and open ArcMap and ArcScene. 3. In ArcMap add the following aerial photos from the Aerial folder: sid sid sid sid 4. Explore the aerial photo s and locate our site. The center of our site is just over a mile northwest of the intersection of the four quads. STEP 2: OPENING AND MERGING A DTM IN ARCMAP Preparing the File 1. Open Microsoft Excel. 2. Go to FILE>OPEN and select the following file: dtm. 3. The TEXT IMPORT WIZARD will appear. Choose DELIMITED and press NEXT. Then, select SPACE. Press NEXT and then FINISH. 4. The first column represent the X values, the second column represent the Y values and the third the Z (or the elevations in meters). 5. Insert a row above the first existing row. Label the first column X, the next Y, then Z, then TYPE, and finally CLASS Site and Urban Systems Planning Page 1 of 7

2 6. Go to FILE>SAVE AS and pick DBF IV (dbase) as the file type and call the file dbf. 7. Now perform steps 2-5 for the other dtm files. 8. Close Excel. You will no longer need it. 9. Having saved all of your DBF files you can now bring them into ArcMap. Opening XY Coordinate files in ArcMap 10. In ArcMap go to TOOLS>ADD X Y DATA 11. Pick dbf. The X and Y fields should automatically be populated. 12. Click the Edit button and pick SELECT (to select a coordinate system), then select Projected Coordinate System, pick State Plane, Pick Nad 1983, Pick NAD 1983 StatePlane Massachusetts Island FIPS 2002.prj. Click ADD, then Apply and finally OK. 13. Click OK again to ADD the XY data to your map and the data should appear on your map. 14. Now perform steps on the other dbf files. All the dtm data for the site should now be available. Merging the Files: 15. Open Arc Toolbox (click on the red toolbox symbol) 16. Expand Data Management Tools>General and click Append. 17. Choose one of the dbf files as an Input Feature and one as an Output Feature by clicking on the folder symbol and navigating to where you ve saved the dbf files. 18. If this fails, you may need to first export the dbf files as separate shape files and repeat steps with the shape files. To check if the steps were successful, check the size of your dbf file. If it has doubled in size you re fine. If not, the process failed and you will need to first export shape files. (This whole process was much easier with the Geoprocessing Wizard!) a. To export the dbf X Y data as a shape file, right click on one of the dbf files and select Data>Export Data b. Then, choose a more appropriate name than the Export_Output default name Site and Urban Systems Planning Page 2 of 7

3 STEP 2: CREATING A SURFACE 1. In order to create a Surface you need to make sure that both 3D Analyst and the Spatial Analyst Extensions are open. Go to Tools>Extensions and put a check next to Spatial Analyst and 3D Analyst. 2. Right-click on the ArcMap toolbar and add the Spatial Analyst and 3D Analyst toolbars. 3. In the 3D Analyst drop down menu, select Create/Modify TIN>Create TIN From Features 4. Select dtm use Z as your height source and triangulate as mass points. Call the file tin_hopkinton Site and Urban Systems Planning Page 3 of 7

4 5. The new Theme will be added to your map. Modify the legend by right clicking the source file and picking Properties and then picking the Symbology tab. For example you might change the range of the elevations and their colors. 6. Save your file and minimize ArcMap. STEP 3: OPEN IN ARCSCENE 1. Maximize ArcScene. Add the TIN by clicking the add layer icon and selecting tin_hopkinton. 2. Use the Navigate, Fly, and Zoom tools to explore the TIN Surface. 3. You can exaggerate the heights to get a better understanding of the topography. To perform this operation, right-click on the source layer. Click Properties and pick the Base Heights Tab. 4. Change the Z Unit conversion to 10 and click OK. This change might be a little extreme, but you can clearly see how changing the Z value will effect you image. 5. Minimize ArcScene we will use it later to create an animation. STEP 4: GENERATE CONTOURS 1. Maximize ArcMap. In the 3D Analyst drop down select Surface Analysis >Contours. 2. Your input surface should be tin_hopkinton. Make a contour interval of 3, because our metadata file told us that the data was only good enough to make 3 meter contours. Keep all of the other defaults and call the file contours.shp. 3. The Theme will automatically be added to your view. STEP 5: GENERATE SLOPE MAP 1. In ArcMap go to the 3D Analyst drop down. Pick Surface Analysis>Slope. Make sure that tin_hopkinton is your Input Surface. Change the output cell size to 10, the output cell size tells ArcMap what resolution to make the slope Grid it creates. Call the file hopkinton_slope_ Site and Urban Systems Planning Page 4 of 7

5 2. View the new Theme. 3. Change the range of slopes in the legend to increments of 2% (0-2; 2 4; 4-6; 6-8; 8-10; 10- ). 4. The Theme will automatically be added to your view. STEP 6: GENERATE ASPECT MAP 1. Derive Aspect identifies the steepest down-slope direction from each cell to its neighbors. The values of the output grid theme represent the compass direction of the aspect; 0 is true north, a 90 degree aspect is to the east, and so forth. A legend representing the 8 cardinal directions is assigned to the output grid theme (e.g., east [ degrees], southeast [ ]). 2. In ArcMap go to the 3D Analyst drop down. Pick Surface Analysis>Aspect. Make sure that tin_hopkinton is your Input Surface. Change the output cell size to 10. Call the file hopkinton_aspect. 3. The Theme will automatically be added to your view. STEP 7: GENERATE HILLSHADE MAP 1. Compute Hillshade is used to determine the hypothetical illumination of a surface as part of an analysis step or for graphical display. For analysis, Hillshade can be used to determine the length of time and intensity of the sun in a given location. For a graphical display, Compute Hillshade can greatly enhance the relief of a surface when the output is used as the brightness theme for the display of another grid theme. This can be done by attach a hillshade image to a file in ArcCatlog. Various features in the input grid or TIN theme can be accentuated and different effects achieved by altering the azimuth and altitude parameters. The azimuth is expressed in positive degrees from 0 to 360, Site and Urban Systems Planning Page 5 of 7

6 measured clockwise from north. The altitude is expressed in positive degrees, with 0 degrees at the horizon and 90 degrees directly overhead. 2. In ArcMap go to the 3D Analyst drop down. Pick Surface Analysis>Hillshade. Make sure that tin_hopkinton is your Input Surface. Azimuth 90 (East) and Altitude 30 (low angle above the horizon for winter) Change the output cell size to 10. Call the file hopkinton_hill. 3. The Theme will automatically be added to your view. For azimuth and altitude inputs for any point on the globe at any time of the year, visit: STEP 8: DETERMINE LINE OF SIGHT ANALYZING VISIBILITY Line of Sight tells you whether a given target is visible from a particular point of observation. It answers the question, Can I see that from here? 1. Uncheck all the Surfaces you have created so far. This will turn them off in the View. Make sure that your TIN surface is active, by clicking it in the legend. 2. Select the Line of Sight tool from the tool menu. (this is under the small button with contours-to the right of the 3D Analyst drop down). 3. On the Line of Sight dialog, specify how many units the observer and target positions will be offset above the surface. Typically, you don t want to assign the observer an offset of 0.0 or you will have positioned it at ground level. Press OK. A good observer offset might be meters (This is 5 ft.). 4. Press the left mouse button down at the observation point, move the cursor to the target location, and release the button. The result is a graphic added to the view. The visible portions of the line to the target will be added in green; and the non visible portion is in red. A message in the ArcMap status bar at the bottom of the application window will indicate whether the target location is visible. STEP 9: DOCUMENTATION / ANIMATION DOCUMENT Create an 11X17 page layout with the various maps arranged on it. Make sure to include titles, north arrow, and your name. Print in color. If you are not familiar with the ArcMap publishing tools you can make the layout in a different software package Site and Urban Systems Planning Page 6 of 7

7 1. To do this task in ArcMap, go to File >Export Map and save the map as one of the image file formats available. To do this task in ArcScene, go to File>Export Scene and pick 2D and then pick one of the file formats available. 2. You can now open the image file in another software package that you are more familiar with to create the layout. ANIMATION 1. In ArcScene right click on the tool bar and add the Animation Tools. 2. Go to the Animation drop down and select Create Keyframe. Click on New to Create a new animation track and select Create to create you first Keyframe. 3. Using the Fly tool, you can repeatedly change your location and create a new keyframes without closing the Create Animation Keyframe dialog box. Note that you need at least two keyframes to create a track that will show change. 4. When you have created all your keyframes, click the play button to see your animation. 5. After you have viewed your animation, export it as a video. Go to the Animation drop down menu and select Export to Video. Save your video and replay it to make sure that it works Site and Urban Systems Planning Page 7 of 7