Lab 4 – Digitizing I


Most of the issues some of y’all experienced Wednesday were due to poor workspace management.  Each of these issues is solved by creating a workspace folder on the c:\ drive and saving/copying/exporting/… everything to it.  This is what I saw Wednesday:

  • Not correctly copying existing workspace from your network drive to the c:\ drive:  You created your workspace on the c:\ drive and you saved your ArcMap project and all of the data you used/created in your c:\ drive workspace.  Up to this point, all is well.  When you finished work on your project, you copied your c:\ drive workspace folder up to your network space (the m:\ drive).  Now, back at the computer terminal, you opened your ArcMap project from your network space (the m:\ drive) and the layers in your TOC all had the red-!-of-death.  This approach does not work.  You created and saved a project that references data layers from your c:\ drive workspace; the workspace is deleted every time the computer is rebooted.  You should have copied the folder from your network drive (the m:\ drive) onto the c:\ drive and then open the ArcMap project residing in that c:\ drive workspace folder.
  • Not copying downloaded data from the Downloads folder to your c:\ drive workspace:  Chrome and Internet Explorer and Firefox default to your Downloads folder.  Your Downloads folder is saved in a hidden folder on the d:\ drive.  This drive is not mapped to ArcMap.  Every time you download a GIS layer, copy it from this Downloads folder to your c:\ drive workspace and then uncompress it.  I set these computers up so ArcMap does not scan the d:\ drive for speed purposes, so if you leave your GIS layers in the Downloads folder then you will not be able to access them by default.  Save everything to your c:\ drive workspace folder.
  • Not explicitly supplying the output location:  Most ArcMap dialogs will either ask for an “Output dataset” or an “Output location”.  Every time, you need to use the file/open dialog button to navigate, in the first case, to your c:\ drive workspace and enter a new file name, or in the second case, navigate to your c:\ drive workspace folder.  If you do not do this, the outputs will be saved in your profile folder on thed:\ drive that ArcMap can not see by default.

In lab today, before doing anything else, I want you to demonstrate your understanding of the digitizing process before you begin work on the Walton county map.

  1. Create working directory on C:\ drive called “l4test”
  2. Download this file (Lab4_aerial_NAIP2015.img) and then copy it over to c:\l4test
  3. Download the test file geodatabase I created for you and copy it over to c:\l4test
    • This file is compressed, you have to uncompress it before you use it.  Navigate to c:\l4test in File Explorer – you should see the l4testgdb.gdb.zip file you just downloaded.  Right-click on it > Extract All > MAKE SURE THE EXTRACT PATH POINTS TO C:\L4TEST\ > hit ok
  4. Start a NEW INSTANCE of ArcMap
    • Save your project as “l4testproject” into the c:\l4test folder.  Notice the home folder is set in the Catalog as c:\l4test\.
    • Set the data frame coordinate system (view > data frame properties menu > coordinate system tab > projected>utm>nad 1983>zone 17N
    • Save your project again
  5. Add the image you downloaded in step 2 to your project.  This is your georeferenced data source.
  6. I HAVE ALREADY DONE THIS FOR YOU.  LOAD THE l4type FEATURE CLASS FROM THE GEODATABASE YOU DOWNLOADED IN STEP 3.
    Create a new file geodatabase in c:\l4test called “l4testgdb”

    • Create a new feature class called “l4type” inside the geodatabase you just created
      • should be a polygon
      • add a TEXT field called “mytype”
      • add a FLOAT field called “myacres”
      • your new layer, l4type, should now be in the table of contents
  7. Right-click on l4type > Edit Features > Start Editing (do it this way, it is easier)
  8. Select your edit feature (l4type) in the ‘Create Features’ window
    • if it does not appear, Editor tool bar > editing windows > create features)
  9. I will spend time today explaining the next steps – creating and cutting polygons.  This information is also in Wednesday’s lecture document.

 

I will post the lab after I see that y’all understand the process.

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