General Questions
Question: "Am I required to print my homework in color?"
Response: Unless explicitly instructed to print a particular assignment in color, you are not required to do so. Grayscale printing is generally acceptable for most homework assignments.
Question: "Do my color maps / color schemes / symbol colors have to match what I see in the book or in the exercise example?"
Response: Note that sometimes when adding a layer, ArcMap picks a random color scheme, so your map may differ slightly from what is presented in the book / exercise. You only need to change your symbol/layer colors when the book tells you to do so, or if it is difficult to distinguish layers when printing in grayscale.
Question: "What scale/extents should we use for a map when grabbing a screenshot?"
Response: Unless the book or exercise specifically tells you to set the map to a certain scale or zoom to a particular area, there are generally no requirements what scale is needed. What is important is that you are showing what is requested (e.g. a certain area on the map, etc), and that it is visible/legible when printed.
Question: "I saved all my GIS assignments to my flash drive and tried to open up one of the files again and none of the data is showing up. In the table to the left there's a bunch of red exclamation points and I'm not really sure what's going on."
Response: ArcGIS is sensitive to where on your computer you save the various layers and data sources. So if you change the path by moving your folders without putting them in the same path, then ArcGIS cannot find these layers because it does not know where to look. You will get a red exclamation point next to your layer (see below) when this happens. The best thing to do to avoid this is to always be consistent in where you save your files and all supporting files. You can repath the layers one-by-one by right clicking on each, clicking "properties", then go to the "Source" tab and click "Set Data Source...". Then navigate to where the data is located on your computer. This can be a huge headache, especially if you have many layers, so I highly recommend always saving your files so they have the same path, regardless of which computer you are using.
| I found this symbol... | ...what does it mean? What can I do to fix this? |
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This symbol (grayed square with red exclamation mark) indicates that the data source for the "Countries" layer cannot be found. See these guidelines for tips on how to fix this issue. |
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The "Rivers" layer will not display because you are zoomed out too far. Try manually zooming in, or right click on layer and select "Zoom to Layer" |
Homework #1
No questions asked.
Homework #2
Exercise 5b: "It said After step 20, Produce a map that shows the navigable rivers only in Africa symbolized by the "river" symbol. But I'm not sure how to show just the rivers in Africa and when I look at the attributes table for countries, there is no name call Africa. So I wonder what steps I should follow in order to produce that map."
Response: After step 20, you should be working with the "Rivers layer" within the "Rivers" data frame. You should no longer be working in the "Countries" data frame. If you cannot see the rivers on your map, make sure that the Rivers data frame is activated. To do this, right click on Rivers (the one with the yellow symbol, and click "activate." Now to show just the navigable rivers, repeat steps 14-19, but work with "NAVIG" in the Value Field instead of "TYPE". You will need to do one more step to make just the "navigable" segments visible, while making the "nonnavigable" segments invisible.
Exercise 6-b: "Are we only required to print off a layout for Exercise 6b? It just says to "follow the steps assigned in the book"
Response: Yes, for Exercise 6b, all you have to do is follow the steps. No print layout is required for this section.
Homework #3
Exercise 7a: "This exercise asks to put labels for each feature from the data table, I think this would be done in the properties under the label tab under expressions, but I'm having trouble getting both the FID and NAME labels into it, and it keeps coming up with an error. How is the label expression supposed to read?"
Response: The expression editor can be really sensitive to how you write the equation. Try this format:
[FIRST ATTRIBUTE] + " " + [SECOND ATTRIBUTE]
but replace the first and second attributes with the appropriate names, being sure to include the brackets.
Exercise 8a: "I'm on question 8a-1 and am trying to find the length of the streets surrounding the top left block of parcels but am unsure of how to do it. I have tried selecting each of the parcels within that block and looked for some kind of "length" attribute in the attributes table. However, all I find that could possibly help at all is a "sq ft" column, but even that has only one value in the table. Could you possibly give me any hints on where to go from here?"
Response: The point of this exercise is to become familiar with the select attributes functions, instead of just looking up the entries in the attribute table. As you noted, there are no street length entries in the attribute table. To use the select attribute tools to determine the length of the streets around the parcel, you will need to: (1) Set the selectable layer to "streets" only, (2) Ensure that the selection tolerance is set (Step 9), (3) Use the select features tool (look at Step 11). Click and drag to select new features. You will need to change the interactive selection method so you can select multiple street segments, and (4) Use the statistics tool in the selection pull down to see the total length.
Exercise 9b: 9b-2 says: "Follow the steps in the last paragraph of step 28..."What does that exactly mean?"
Response: The assignment here actually should read "the last paragraph of step 29." The assignment is referring the the paragraph that reads "An interesting follow-up to your work...... that contain lead." So you will need to join the Remedial_actions and Pits_75 tables, and relate the metals table to that joined table. Then freeze the required fields (IDnumber, PIT_TYPE, STATUS, RANKING, and CLEANUP) to maintain them and take a screen shot.
Exercise L-1 and L-2: "I feel confused about the lecture questions (L-1 and L-2) in homework 3. Could you please explain them a little bit for me??"
Response: For the topological tables assignment (L-1), you can find explanations in the class notes - look in the section called "I - Vector Data Structures" and "B.2 Area Definition". You need to have three topological tables, one for the Polygon Topology, one for the Node Topology, and one for the Line/Arc Topology. You do not need a table for the coordinates of the nodes or arcs. You can find a similar example on page 17 of this manual.
For the run length encoding assignment (L-2), there is an example in your notes in the "II - Raster (Grid) Data Model" section. Look at Figure 4.22 in this section. The purpose of run length encoding is to minimize the amount of information stored for a raster, so you can reduce the space required for that dataset. It acts as a data compression algorithm. You can also find a nice example on Wikipedia, but make sure you do a separate line of run-length encoding for each row in the raster.
Homework #4
Exercise 10a: "I am attempting to do GIS homework 4 however in exercise 10a step 7 I keep getting an error that says "An unexpected error occurred in the Select by Location command." What is going on here?
Response: The reason why you are getting this error is because the data in the "C:\CEE424_GIS\GTKArcGIS" folder of the More Lab computers is "read-only." The simple solution is to always copy the Chapter folders from the ESRI Press folder to somewhere where students have write-permission, such as the computer desktop. If you copy the chapter folders to the desktop, you should not encounter this error any more.
Exercise 11a: "When I get to step 12 and hit okay, it fails to dissolve, making me unable to continue. The same problem persists with the dissolve, clip, and buffer tools. I tried on 4 different computer down in CEE lab. What is going on here?
Response: The reason why you are getting this error is because the data in the "C:\CEE424_GIS\GTKArcGIS" folder of the More Lab computers is "read-only." The simple solution is to always copy the Chapter folders from the ESRI Press folder to somewhere where students have write-permission, such as the computer desktop. If you copy the chapter folders to the desktop, you should not encounter this error any more.
Homework #5
Exercise 14-2: "I am rather confused with question 14b-2 Could you please explain a bit more?"
Response: Here is some help from the introduction to 14b in the textbook: "Precision defines the smallest measurement that can be made in a coordinate system. For example, if the coordinate system units are feet, a precision of 12 allows you to make measurements as small as 1 inch. If the coordinate system units are kilometers, a precision of 1,000 allows you to make measurements as small as 1 meter." The key here is you are looking for the smallest single unit (e.g., 1 meter, 1 inch, 1 foot, etc) that can be measured. So in a coordinate system that is in kilometers, a precision of 1,000,000 allows measurements as small as 1 millimeter.
Exercise 14-3: "Question 14-3 for this week's homework does not seem to be covered in the book and I have looked elsewhere for it without much luck. Do you know where I could find this info?"
Response: When you are answering this problem, think of the folder system in Microsoft Windows or in the Macintosh Operating System. The key here is to see how this organizational structure in Windows/Mac is similar to how things are organized in a Geodatabase. Carefully look at the Geodatabase screenshot, and this should help you answer the question about how the organizational system is related.
Homework #6
Exercise 16a: "I am trying to do my HW 6 from the computer lab. At the very beginning, Exercise 16a, step 4 at page 418 - Start Editing button is not active, neither the Edit tool from the Editor Tool bar. What should I do?"
Response: The reason why you are getting this problem is because the data in the "C:\CEE424_GIS\GTKArcGIS" folder of the More Lab computers is "read-only." The simple solution is to always copy the Chapter folders from the ESRI Press folder to somewhere where students have write-permission, such as the computer desktop. If you copy the chapter folders to the desktop, you should not encounter this problem any more.
Exercise 17a-c:"There is no MyData folder in chapter 17 in the More Hall computer lab machines. Can I still do the assignment?"
Response:This is a non-issue. Create a "MyData" folder on the desktop (or wherever you download the Chapter 17 exercises), and continue with the assignment as usual. This is simply a location where you will save your datasets as you build them.
Exercise 17c:"In Steps 7-12, the textbook screen shots are different from what I am seeing on my computer. What is going on here?"
Response:At this stage in the exercise, you are matching the three unmatched addresses. These may appear in a different order than what is presented in the book, which is why you are seeing this difference. In step 7, you should choose the record corresponding to 725 Lakeview Ave NE, and change the zip code from 30309 to 30308, then match it to the candidate with score=100. In step 8, you should choose the record corresponding to 751 Juniper, and then match it to the candidate with score=84.73. In step 12, select the final unmatched record, change "MIRTEL" to "MYRTLE" (note two misspellings), then select the candidate with score=100.
Exercise 17c: "How do I add a new row after Step 17?"
Response: 1) Click Editor -> Start Editing 2) ArcGIS will give you three folders that you can edit. You must choose the one where your customers table is located, which should be in the "Chapter17\Ex17aData" folder. Choose that folder, and click start editing in the following dialogue box. 3) In the table of contents, make sure you are in the "Source" tab. Right click on Customers and open the attribute table. 4) To add a new row, just double click on the empty field below the OID=15 row. Note that you cannot double click in many of the early columns, so start with the CUST_ID column. As soon as you enter values there, ArcGIS will put "16" in the OID column of the new row and "Point" in the Shape column of the new row. Complete the rest of entries for Kamal (CUST_ID, NAME, ADDRESS, ZIP, TYPE). 5) Close the attribute table. 6) Click Editor -> Stop Editing 7) Now Geocode this address (with 80% spelling sensitivity) using the techniques you learned in this exercise.
Exercise 17c: "Question 17c-1 directs us to add a record in the attribute table for a new customer. We are then asked about how many match candidates we got and what the score was for them. The trouble is that with the zip set to 3038, we get no candidates - just as in the first example from the book, wherein the zip was incorrectly set to 30309. Are we meant to answer the question for the case where zip = 3038 and there are no matches, or should we repair the data so that zip = 30308 and we have a few (weak) matches?"
Response: I will accept either approach here. If you use ZIP=3038 and receive no matches, explain why you received no matches. If you use ZIP=30308, report how many candidates were returned, and what was the best score. Did ArcGIS do a reasonable job here?
Homework #7
Spatial Analyst "I am working with the book version of ArcGIS on my home computer. How do I install the spatial analyst extension?"
Response: To Install the Spatial Analyst Extension: Insert the software install cd, choose "Install ArcGis", Select "Modify" and click next, Click the plus next to "Extensions," then select "Spatial Analyst" and choose "Entire Feature will be installed". Click "Next" twice. Installation will takes a few minutes. Click "Finish" when it is done.
To get permission to use the extension: Close ArcMap , Open Start --> All Programs --> ArcGIS --> Desktop Administrator. Click "Register Single Use and Extensions." Click "Register Now". Select "I have already installed and need to register additional extensions". Click "Next," accepting defaults, a few times, until you reach a screen Called "Evaluate ArcGIS extensions. Select the radio button allowing you to choose individual extensions. Select "Spatial Analyst" and click "Next". Wait until registration is complete, then close the desktop administrator and reopen ArcMap.
Turn on the extension. In ArcMap, choose Tools->Extensions. Check the box by Spatial Analyst and close the window. The Spatial Analyst toolbar is now available and ready to be used in the View --> Toolbars menu.
Homework #8
Question: "I saved all my GIS assignments to my flash drive and tried to open up one of the files again and none of the data is showing up. In the table to the left there's a bunch of red exclamation points and I'm not really sure what's going on."
Response: ArcGIS is sensitive to where on your computer you save the various layers and data sources. So if you change the path by moving your folders without putting them in the same path, then ArcGIS cannot find these layers because it does not know where to look. The best thing to do to avoid this is to always be consistent in where you save your files and all supporting files. You can repath the layers one-by-one by right clicking on each, clicking "properties", then go to the "Source" tab and click "Set Data Source...". Then navigate to where the data is located on your computer. This can be a huge headache, especially if you have many layers, so I highly recommend always saving your files so they have the same path, regardless of which computer you are using.