Fall 2013
   GEO327G/386G: GIS & GPS Applications in Earth Sciences


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Lab 9:  GPS Data Collection Preparation - Maps, Instruments and ArcPad Software


 

9.1 Objectives

This Lab contains 2 parts. In Part A, to be done in lab, you will:

  1. Create a geodatabase to contain existing data for the field area we will visit this weekend;
  2. Create a feature dataset containing empty polygon, line and point feature classes with domains for field data entry;
  3. Create a project containing all data needed for field data collection;
  4. Print layouts and instructions for data collection to take with you to the field;
  5. Export your project to an ArcPad v.10 project;

In Part B, to be done during the class lecture period you will:

  1. Learn procedures for capturing GPS points, lines and polygons with ArcPad 8 software;
  2. In pairs, use a Trimble Nomad GPS receiver to capture the locations of polygons and lines on the East Campus Mall and circle drive.

9.2 Geodatabase Preparation with ArcGIS 10.0

Most data for this project are available in shapefile format, but we will find it useful to build a geodatabase so that we can establish domains for data entry.  We will be collecting data with ArcPad software, which permits the capture of GPS positions for points and vertices and uses forms for entering attributes while in the field.  By using coded value domains in our geodatabase, we can create drop-down menus for our forms, a far easier way to enter attributes than pecking letters with a stylus on a virtual keyboard.  Recent versions of ArcPad (7.0 and above) also allow the option of "checking out" Feature Classes from a database for field editing with ArcPad, then checking them back in when finished.  When it works properly, this is a very efficient way of editing a field-based GIS, eliminating the need to update existing files by appending, merging or otherwise editing them to conform to new field data.  You have already done many of the steps below in Lab 4. Refer to it if you've forgotten aspects of geodatabase Feature Class and Domain creation.

  1. Download the Lab_8_data folder to your personal storage space.
     
  2. Open ArcCatalog and browse to your Lab_8_data folder.
     
  3. Create a personal geodatabase called "Mason_Mt_WMA" (= Wildlife Management Area) within the Lab_8_data folder.
     
  4. Right-click on your new geodatabase and import all of the Feature Classes in the Lab_8_data folder (and subfolders) into the geodatabase. The spatial reference for all of these feature classes is NAD83, UTM zone 14N, and they will import as such.
     
  5. Geodatabases can not hold layer files (these files contain the symbology for the feature classes you just imported) yet we would like to use the layer files to symbolize the new geodatabase feature classes. To do so we must reset the source for the layer files.

    Right-click on a layer file icon, select "Properties...", click the Source tab then the "Set Data Source..." button and reset the source by browsing to the appropriate Feature Class in your geodatabase. Do this for all Feature Class layer files (but not raster layer files).
     
  6. What about the raster files?  The Lab_8_data folder contains two very high resolution DOQs (one multiband color, one single band panochromatic) and a hillshade raster with associated layer files; should we import these into the geodatabase? In this case the disadvantages of doing so outweigh any advantage. In particular, the color DOQ is a large MrSID file that would get much larger when uncompressed and stored in IMG format, which is the format required by the geodatabase. There is no real advantage to doing this, other than having everything in a single container, and we are left with a file that is >150 Mb. We could instead create a geodatabase raster index (see Help files on this topic), but for the few rasters we will work with this also provides no real advantage. We will keep the rasters separate from the geodatabase for these reasons.
     
  7. Time to create the empty Feature Classes that will contain the GPS-derived points lines and areas... 
  1. Before doing so, it is good practice to create a Feature Dataset that will contain the new Feature Classes (this is similar to creating a feature dataset when we digitized in Lab 4; we are digitizing in the field using a GPS instrument).  To do so, right-click on the Mason_Mt_WMA geodatabase icon, select "New...", then create a new Feature Dataset called "Geology".  SET THE SPATIAL REFERENCE OF THE FEATURE DATASET TO NAD83 UTM zone 14N, SET THE "Z COORDINATE SYSTEM" TO <None> AND ACCEPT THE DEFAULT XY TOLERANCES. (Note for outside users: the procedure for doing this in ArcGIS 9.1 is somewhat different.  See an example here).

  2. Now we can create the Feature Classes; right-click on the Geology Feature Dataset icon, select "New...", then create new Polygon, Line and Point Feature Classes (named Polygon_XX, Line_XX and Point_XX, where XX is your first and last initial).  Do this step 3 times, one for each Feature Class, being sure to change the Geometry type [polygon, line, point] to match the Feature Class and checking the Geometry Properties box on to allow "Coordinates include Z Values" as shown below.

New Feature Class
 

  1. The polygon feature class will be used to store the GPS-derived outline of granite outcrops and any other features that are polygons.  We need an attribute field that records the feature being mapped (e.g. "granite", "pegmatite" or “other”) that can be entered as we collect the data.  So... add two Text fields to the polygon feature class, one called "FEATURE" and another called "COMMENT". The length of the FEATURE field should be 9 and the COMMENT field 30.  Leave all other Field Properties blank for now.  Please use these precise field names, including capitalization, for this and all other feature classes. Merging and appending files from different GPS receivers is much easier if everyone uses exactly the same field names and properties.
     
  2. Create a Domain (by right-clicking on the Mason_Mt_WMA geodatabase icon, then Properties...) called PLY_TYPE, (Field Type is Text) that is a coded-value domain containing the coded values of "granite", "pegmatite", and "other" (see Lab 4) and then attach this domain to the polygon attribute field FEATURE (again see Lab 4).

    1. The line Feature Class will be used to store rock unit contacts or outcrop boundaries that can't immediately be seen to close on themselves (i.e. can’t be mapped as polygons). The attributes that will be recorded and the new fields to create are:

      i. 9-character text field, called  "FEATURE", that will contain coded values from a text Domain called "LN_TYPE" of "contact", "outcrop" and "other".

      ii. 7-character text field, called "SYMBOL",  that will contain coded values from a text Domain called "Symbol" of "solid", "dashed" and "dotted".

      iii. 30 character text field, called "COMMENT", without an attached domain.


  3. Create these new Fields and their Domains with the above coded values and attach the Domains to the Fields, as in steps c and f.

  4. The point Feature Class will be used to record the location of features too small to recorded as polygons and for strike and dip measurements. We will need fields for:

    1. 10-character text field, called "PT_TYPE", that will contain coded values from a text Domain called "PT_TYPE" of "joint", "foliation", "bedding", "dike" and "other".
    2. 3-character short integer field (Precision equals 3), called "STRIKE", that will contain coded values from a short integer Domain called "strike" of every third integers between 0 and 357 (i.e. Codes of 0, 3, 6, 9, 12 etc. with Descriptions of 000, 003, 006, 009, 012, etc. to 357; yes, all 120 values).
    3. 2-character short integer field (Precision equals 2), called "DIP", that will contain coded values from a short integer Domain called “dip” of every second integer between 2 and 90 (i.e. Codes of 02, 04, 06, etc., with Descriptions of 02, 04, 06 etc.; 44 values in all).
    4. 30-character text field, called "COMMENT", without an attached domain.

  5. Create these new Fields and their Domains with the above coded values and attach the Domains to the Fields, as in steps c and d.

Congratulations, you have now completed the database you will need for this project.

9.3 Making Field Maps

  1. Open ArcMap with an empty map document and load all of the LAYER FILES (not the Feature Classes), including the layer files for the DOQ and Hillshade.  If this doesn't work, you skipped Step 5 above.

  2. Load your empty polygon_XX, line_XX and point_XX Feature Classes you just created and move them to the top of the Table of Contents if not already there.

  3. Order the remaining layers so that the Hillshade is at the bottom, the DOQ is second from the bottom, and all remaining layers above these.
  4. Set the Display Properties of the rock units and the outcrop polygons to 50% transparent.

  5. Zoom to the WMA boundary layer, reset the reference scale, and SAVE THE MAP document to your Lab_8 folder.

Switch to Layout mode and make a map with a 50 meter UTM grid, scale bar, north arrow, name, etc.  Print two maps, one with the hillshade layer turned on and another with the hillshade off but the DOQ on. The scale should be ~ 1:10,000 to be useful; you will have to tile the map onto a few pieces of paper to cover the area of interest (Julio will tell you how much of the area to print), which is within the portion of the WMA that is within granite southeast of Mason Mountain and along the western boundary within granite.  Bring these maps with you on the field trip.

9.4 Trimble Nomad and ArcPad v. 10

GPS data collection using the Trimble Nomad units is done with ArcPad software.  ArcPad is a streamlined version of ArcGIS that is equipped with very easy to use GPS capture tools.  ArcPad 10 is installed on the classroom computers and our field data collection units.  Version 10 is a major revision from earlier releases.  Before getting a little ArcPad practice, we first need to convert the ArcGIS map document file into an "ArcPad Project".  An automated tool exists to do so, which converts most rasters to jpeg images, the geodatabase to an ArcPad exchange format database (.AXF), and makes data entry forms from the domains for each Feature Class.  We can "check out" the empty Feature Classes for editing then, upon return, "check in" the same, permitting the software to automatically update the geodatabase!

An important note about ArcPad versions:

  • ArcPad 10 represents a significant departure from earlier versions (i.e. 8.x and below).  "ArcPad Projects" created for ArcPad 10 will not run on 6.x software, and vice-versa.  The ArcMap toolbar for creating ArcPad projects in versions of ArcGIS 9.1 and higher contains separate tools for creating ArcPad 8.x and 6.x (or lower) projects.  It is thus important to know which version of ArcPad is installed on your field data collection units.  Our Trimble Nomads and Xplore tablet PCs are currently running ArcPad 10, as are the computers in the lab

A. Preparing the Map Document for ArcPad (version 10).

  1. Open your map document.
     
  2. Switch to Data View mode (if you're in Layout mode) and zoom to the WMA_boundary layer.  This is an important step!
     
  3. Make sure the "Point_XX", "Line_XX" and "Polygon_XX" Feature Classes are present in the Table of Contents of the map.  These are empty, but have coded-value domains already built that will allow use of ArcPad data entry forms.  These are the files you will populate with GPS measurements.
     
  4. Change the symbology of these files to colors/symbols that will be recognizable on both a white background and the DOQ.  Red works well, as does light blue.  This is much easier to do now than later in ArcPad.
     
  5. If not already on. Turn on the ArcPad Data Manager toolbar (Tools>customize...) shown below.
     

  1. On the ArcPad toolbar, click the "Get Data for ArcPad" button.
     
In the "Select Data" window, shown below, there are several options for how to export data under the "Action" column.  The "action" performed on each layer can be set individually or for all layers by clicking on the word "Action" to display the menu shown in the figure below.  Strictly speaking, we can either "Checkout" a layer for editing or "Copyout" a layer.  A "Checkout" is only allowed for Geodatabase layers; shapefiles or other layers not in a geodatabase can be "Copied Out".  A "Checkout" creates a compact geodatabase that can only be read by ArcPad in a so-called "AXF" (Arc Pad Exchange Format) file.   There are numerous advantages to AXF files - read about them on page 573 of the ArcPad Help PDF in the Lab 8_data folder.  For our purposes, the principal advantage is the automatic creation of forms (based on our geodatabase domains) that can be edited in the field, and the ability to directly import the results into our ArcGIS project after returning from the field.  The main disadvantage is that a Checkout is tied to a specific ArcGIS file, your project, on a specific computer.  After data collection, the file can only be checked into your project (into your geodatabase) on the computer you created it on.  An AXF file can not be edited by any software, so if you are unable to check it back in, for whatever reason, you've lost all of your field results.

The other option, "Copyout", creates a Shapefile that can be read by ArcPad.  Unfortunately, this option does not automatically create forms for field editing, nor can results be directly checked back into your ArcGIS file after field work is done.  The shapefiles can, however, be downloaded from the receiver onto a computer and loaded into your ArcGIS project by the same process you would use to load any other shapefile.  "Copyout" layers are exported to ArcPad as "background layers" that either can be editable or not.
   
We will cover several bases by "Checking Out" the three files we will edit in the field (Point_XX, Line_XX, Polygon_XX), "Copyout" the "Outcrop-Lines_sample" layer as an editable background shapefile, and "Copyout" all other files (those we will not edit) as "read-only" background shapefiles.  I will explain the rationale during lecture.  To do this requires specifying the "action" for each layer individually.
  1. Click the black arrowhead to the left of your "Line_XX" Layer and choose "Checkout for disconnected editing in ArcPad>data based on defined extent".  Do the same for the Point_XX and Layer_XX layers.
     
  2. For the "Outcrop_lines_sample" layer, choose the action "Export as background data>Make Editable.
  3. For all other vector layers choose "Export as Background data (to AXF layer)>Make Read Only"
  4. Do not export the raster files.
  5. Click Next.

Get data for ArcPad window

  1. The next window, "Select Picture Options", is not applicable to this project; Click Next.
  2. The final window lets you set the spatial extent (current display extent or full extent of the layers), lets you select whether to limit the fields to those that are visible in the attribute tables and the features to those specified in the layer's definition query, lets you specify a name for the folder that will store the data, and lets you create an ArcPad map file (the equivalent of an .mxd file) for the data, as shown in the "Get Data For ArcPad" screen capture below.
     
  3. Enter a name for the folder, e.g. "ArcPad_WMA_XX" (where XX are your initials) and a Map Name that includes your last name or initials (e.g. WMA09_XX).
     
  4. Making sure first that your display shows the entire area of interest (i.e. you are zoomed to the WMA boundary layer), make the selections shown in the figure below, setting the "Where do you want the folder to be stored?" to an appropriate location on your network storage space.

  1. Click Finish and wait for the data to be created.
     
  2. With help from Julio, transfer your new "ArcPad_RR_XX" folder to your Trimble Nomad (these will be shared, but each partner can load a project). The Nomad units have a folder called "My Documents" that should be used for all ArcPad data and files.

  3. Print a color copy of the PDF file "ArcPad Quick Reference", in color, from All Programs>ArcGIS>ArcPad 10>Help>ArcPad Quick Reference.  You will find this exceptionally useful for Part B of this lab, and for the field trip.

Part B: Practice with ArcPad in the field

9B.1 Using ArcPad - some practice with the basics

Editing in ArcPad is, in most ways, much simpler than Editing in ArcGIS.  The basic concept is the same in both - data are entered into a file that is open for editing.  Below are a few of the basics.  A complete description of the software can be found in the ArcPad 10 folder in the class folder.

  1. On a classroom computer, open ArcPad 10 from the Start Button>All Programs menu in Windows.
     
  2. Click the folder button at the top of the ArcPad window and select  "Open Map", then browse to your ArcPad map file, the one with the ".apm" extension, in your "ArcPad_RR_XX" folder.

  3.  Five toolbars are immediately available (called Main Tools, Browse Tools Edit Tools Quick Capture and Navigation), though only one at timeis displayed  (this saves real estate on small screens).

  1. Click the Main Tools icon (on the left in the figure above) and then select the Layers icon to open up a Table of Contents, like that on the left below.  The diagram on the right, from an earlier version of ArcPad, has many of the icons labeled.

  1. The check boxes on the left in the "eye" column turn layers on and off for viewing.  The check boxes in the "pencil" column turn layers on and off for editing.  This is similar to setting the "Target" of the editing toolbar in ArcGIS, except that in ArcPad more than one layer can be open for editing at a time.  In the Table of Contents to the right above, none of the layers are open for editing. In the table of contents on the left above three layers (Point, Line, Polygon) are open for editing. Finally, the check boxes below the Info icon (i) make layers available for query.  Layer Properties can be accessed by an icon on the right, as can other options denoted by icons that should be familiar from ArcMap.  The column with the "rocket ship" icon at the top is the QuickDraw mode; checking boxes here allows the different layers to be drawn to different "coarseness" so they will render quicker on screen.  The QuickDraw mode is accessed from the Editing Toolbar.

  2. Turn on the "Point_XX" layer for editing and close the Table of Contents.

  3. Turn on the Edit toolbar by selecting it from top row of icons, as shown below.

  1. The function of the edit tools are shown in the figure below.  This is the most important toolbar for the field work this weekend.  Learn it.

To add a point to the map, Click the pencil tool, select the layer you want to edit, click the "Capture a point feature" button, (Capture of polyline or polygon features, if open for editing in the TOC, can be selecting from the drop-down menu below the "capture a point" feature icon). Then click a location on the map.  A data entry form should then open, allowing you to select the feature name from a drop down list.

To do outdoors: To add a GPS location as a point, click instead the "Capture a point using GPS" button. (When the GPS is active this button is not grayed-out.)

  1. To add a line, click the Pencil icon, select the polyline feature class you want to edit, click the drop-down arrow below to the "Capture a point feature" button, and select "Polyline".  Click on the map where you wish to place a polyline vertex, click and drag on the next spot where you want a vertex, and continue this process until finished.  The line is not completed until you click the "Proceed or complete feature" button at the bottom of the ArcPad window (shown below).


  1. To do outdoors: To add GPS vertices to a polyline, as above, click the "Capture a polyline" button (beneath the capture a point button), click the "Add a single vertex from a GPS position" button and continue clicking this button every time you want to add a vertex to the line.  To finish the line, click the "Proceed or complete feature" button, the green arrow icon. The line is not completed until you click the "Proceed or complete feature" icon.

    The GPS must be activated before the GPS buttons are available. 

  2. A similar procedure is used to capture polygon vertices with and without GPS.

  3. You can delete features by selecting them with the Arrow button (shown above) and then clicking the "Edit vertices" button.

  4. Practice adding and deleting lines, points and polygons to the map.  Name the features test1, test2, etc. so that, if needed, you will be able to recognize and delete them later.

  5. Browse the ArcPad manual in the digital books folder, particularly the sections on editing.  Download and print the ArcPad Quick Reference page.

  6. Before loading your WMA ArcPad folders to the field GPS units, clear each of your test features, or don't save your project after editing.

9B.2

  1. Before our field trip, you need practice using ArcPad with a GPS. An ArcPad project for the Main Building area, identical to the ArcGIS project you constructed in Lab 6, is loaded on all instruments.  Take your instrument outside, open the Main Building project, and practice capturing lines, points and polygons using the ArcPad GPS tools described above.

  2. Specifically, capture the features listed and labeled in the photo below.

Layout with GPS points

  • Points: Points at the two flagpoles.
  • L1, L2, L3: Polylines with at least 3 GPS vertices at the edges of sidewalks.
  • P1, P2: Polygons outlining grass areas - capture the vertices of the 4 corners with GPS.

You're done.


 Last updated October 18, 2018
 Comments and questions to helper@mail.utexas.edu
 Geological Sciences, U. Texas at Austin