GEOG 4/575 Lab 5: Spatial Data Editing and Topology

Due Nov 5.

You will use ArcMap’s editor, topology editor, and spatial adjustment tools to edit features in shapefiles and geodatabase feature classes. These are fundamental skills in digital map compilation and spatial data automation. Map editing is an intricate task both in terms of using the GUI and doing the sketch. You need to pay extra attention to the steps described in the text. If you miss one step, then the subsequent steps might not be working the way you expect. You can always undo your editing and restore the data back to where you last saved your edits.

Finish all tasks in Chang’s Chapter 7. Answer and submit all questions listed at the end of this exercise. Lab exercise data are available in: I:\Students\Instructors\Geoffrey_Duh\GEOG4575\Chang_5e\chap7 (or on the textbook CD). Please copy all these folders to your working directory in c:\Users before you start.

Notes:

Task 5, Step 1. First use the Define Projection tool to set the projection of both mrblemtn and hoytmtn feature classes to “NAD_1983_UTM_Zone_18N”. Then, use ArcCatalog to export the hoytmtn to a shapefile. Save the shapefile with the same name in your Lab 5 folder. You will need the original hoytmtn to produce the map for Question 2. Make sure that you use the shapefile instead of the feature class in the personal geodatabase as the source layer in the exercise.

Task 5, Step 2. When selecting snapping in Step 2, check both vertex and edge boxes for both layers.

Task 5, Step 5. You will need to zoom in really close to see the link arrows. Each time you apply the Edge Match tool, matched links are added to a link table. Repeatedly applying the Edge Match tool on the same location creates multiple links for the same pairs of points to be matched. This is why the numbers of links that you create might be different from what the text indicates. This will not affect the adjustment.

Task 5, Additional step. After the two feature classes are edgematched, use the MERGE tool to combine them into one feature class and save it in the personal geodatabase. Then use the DISSOLVE tool to remove the artificial boundary on the merged feature class. On the DISSOLVE tool dialog, specify MINOR1 as the dissolve field and uncheck the “Create Multipart Feature” checkbox.

Questions:

1) If you had entered 10 meters for the cluster tolerance in Task 2, Step 2, what would have happened to trial_dig and land_dig? Provide pictures (i.e., screenshots) to illustrate.

2) Produce a map showing the original maps (hoytmtn & mrblemtn) used in Task 5 and the final dissolved map (produced in Task 5’s additional step using the MERGE and DISSOLVE tools). If you didn’t make a copy of the hoytmtn, you can find the unadjusted original hoytmtn featureclass in the instructor’s folder.

3) After you finished the merge and dissolve tools in Task 5, you will notice a segment of the artificial boundary still exists. That segment was formed as a void between the two neighboring polygons. Experiment with ArcMap’s editing tools and describe your method of removing the last segment of the artificial boundary. Please insert a picture showing the final map with all the artificial boundaries removed.