Lab 5: Introduction to GPS

Introduction

In this lab, students will learn the basics of using a Trimble Juno GPS and ArcPad to collect data in the field. A geodatabase and three feature classes will need to be made and loaded into the GPS prior to collecting data. The study area is UWEC's newly developed Campus Mall. Four designated polygons, a footbridge, three trees, and three light poles are too be mapped. This lab is only meant as an intro to GPS data collection for vector map creation.

A GPS unit collects position and elevation data at locations on the Earth's surface by utilizing satellites and ground monitoring stations. The monitoring stations are responsible for tracking and modifying satellite fight paths and monitoring and analyzing satellite signals. There are currently 27 active satellites in 6 different orbital planes.

Figure 1: Illustration of how satellites determine position and elevation.


For an accurate measurement of position and elevation at least 4 satellites need to be available for the GPS to connect to. These satellites transmit radio signals in two frequencies, one is public access and the other is restricted to military use. The transmission of radio signals can be visualized as spheres around the satellite. The position at which all 4 (or more) spheres met is the position of the GPS on the Earth's surface.

Figure 2: Illustration of the effects of satellite geometry.


The position of the satellites available also play a role in accuracy. PDOP stands for positional dilution of precision and is a measure of the effect of satellite geometry, or how the satellites are arranged in space. Low PDOPs indicate a wide spread of satellites which is ideal. High PDOPs indicate a clustering of satellites which can result in larger error.


Methods

First a geodatabase needed to be made. This was done by right clicking the desired folder, hovering over New and selecting File Geodatabase. Then in the catalog window, three feature classes were made by right clicking the newly created geodatabase, hovering over New and selecting Feature Class.... One polygon, one line, and one point feature class were created and given a text field called Type. Each feature class was given the statewide projected coordinate system NAD 1983 HARN Wisconsin TM (meters). These blank feature classes were then added to a black ArcMap document. An image of the Campus area was then imported into the geodatabase by right clicking the geodatabase, hovering over New and selecting Raster Datasets.... Finally, a campus buildings feature class was imported into the geodatabase by the same process above but instead of selecting Raster Datasets..., Feature Class (single) was chosen.

Figure 3: A screenshot of the map document ready to be sent to ArcPad. The color of polygons will transfer into ArcPad, so a bright yellow was chosen to stand out more on a small screen while outdoors.


To enable ArcPad Data Manager, its extension needed to be added by navigating to Customize > Extensions and checking the box next to ArcPad Data Manager. Next the ArcPad Data Manager Toolbar was added by navigating to Customize > Toolbars and selecting ArcPad Data Manager.

Figure 4: The ArcPad Data Manager toolbar. The first button that looks like a GPS unit with an arrow pointing towards the right, the Get Data For ArcPad button, is selected first. Once the data has been collected, the button that looks like a GPS unit with an arrow pointing towards the left, the Get Data From ArcPad button is selected.

Figure 5: Get Data For ArcPad was selected and Next was clicked on the welcome screen. Several things were changed in this window. Action was selected and hovering over defaults, the Background layer format was changed to AXF file and the Background layer editing was changed to Editing allowed. This will allow the feature classes made in the geodatabase to be exported as feature layers in a ArcPad AXF file. Then Action was selected again and Checkout all Geodatabase layers and copyout all other layers was chosen. Next was clicked.


In the next window the folder name, map name, and storage location were selected. Next was clicked. Making sure Create the ArcPad data on this computer now option was checked, Finish was clicked to end the process. A folder will be created where it was specified. This folder contains the background image, an AXF file which contains the editable layers, and a ArcPad Map (APM) file. The folder was copied and pasted in the same location for backup and then pasted again into the Trimble GPS unit. Everything was now ready for data collection in the field.

Figure 6: ArcPad Toolbars. The GPS was turned on and ArCPad 10.2 was opened. The screen looked similar to the one above. In the Main Toolbar (folder icon) the open map icon was chosen and the proper APM file was chosen. The icon to the right of the Main Toolbar icon opens the Browse Toolbar (hand above globe icon). Zooming and panning options are available here.

Figure 7: The Edit Toolbar (pencil with polyline icon). Here the pencil was chosen to begin editing, the desired feature layer was chosen, and the feature type icon on the toolbar (the third icon, looks like a point in this image) was changed to match whichever feature layer was chosen (point, polyline, polygon, etc). For points, once the feature type was selected, the desired features could be collected by selecting the add GPS vertex icon (next to the feature type icon). Once a set number of positions was taken, the GPS averaged the values and generated a single feature. The type field was then modified. For lines and polygons, once the feature type was selected, the Command Bar appeared at the bottom of the screen.

Figure 8: The Command Bar. To collect the desired line or polygon features, the Add a GPS Vertex Continuously (the rightmost icon) was selected. When the feature was complete, the Proceed to Attribute icon was chosen (second icon, big green arrow) and the Type field was modified.

Figure 9: For this Lab, the areas in red were the designated places to collect polygon data, the footbridge seen in the picture was deemed a line, and three trees and three light poles were chosen at random for points.

Figure 10: After the data was collected, the GPS was connected to the computer and the Get Data From ArcPad icon was chosen on the ArcPad Data Manager Toolbar. The green plus sign in the upper right corner of the Get Data From ArcPad window was selected and the appropriate APX file was chosen. The box next to each feature class was checked and the Check in button was clicked. The data collected in the field was now in ArcMap as vector data and a map was made.


Results

Figure 11: The resulting map from the GPS data collection activity. The polygons created were not spectacularly accurate. This could be remedied by slowing the pace of movement around the features to allow more points to be created. The inaccuracy of the data collected is also a result of the capabilities of the GPS used.


Sources

Blog
Figure 1-2 taken directly from class lecture slides
Figure 4-6 taken from the ArcGIS Resource Center. http://help.arcgis.com/en/arcpad/10.0/help/index.html#/Overview_of_ArcPad_toolbars/00s1000000wn000000/
Figure 7 taken directly from Lab 5 instructions.

Data
Aerial Imagery provided by United States Department of Agriculture National Agriculture imagery program 2013.
Campus buildings feature class provided by UWEC Department of Geography and Anthropology.
GPS data collect by Lee Fox.

Lab 4: Operations with Vector

Introduction

Students will apply various vector geoprocessing tools discussed in lecture and practiced in assignments to determine the suitable habitat for Bears in Marquette County, MI. Direction is not given as to what vector geoprocessing tools should be used for each task. These decisions are left up to the student to determine.

Methods

Task One

Determine the total number of bears located within each land cover type.
Provided data: bear_locations_geo.xls and landcover feature class (minor_type)

Figure 1: Start by finding the excel spreadsheet in the catalog window. Right class the desired sheet, and than click Create Feature Class > From XY Table.... The Create Feature Class From XY Table window appears. Here the X, Y, and Z fields, coordinate system, and output location an be chosen. Clicking OK will create bear_locations.shp.

Figure 2: Once the bear_locations,shp has been created it can be spatially joined to the landcover feature class symbolized by minor_type. Right click bear_locations in the Table of Contents and click Joins and Relates > Join.... The Join Data window appears and landcover is chosen in the 1. dropdown menu and the bubble next to "it falls inside" is filled. Clicking OK will create a new point feature class with all the attributes of both bear_locations.shp and landcover.

Figure 3: Opening the attribute table for the newly created feature class, right clicking the minor_type field, and choosing Summerize... will open the Summarize window. Clicking Ok in the Summarize window will create a table summarizing the number of records (bears) in each minor type of landcover. This is that table.


Task Two

Determine the number of bears within 500 meters of a stream.
New Provided data: streams feature class

Figure 4: Use Select by Location. Click Selection in the main toolbar and than Select by Location. The target layer is bear_locations, source layer is streams, and spatial selection method is "are within a distance of the source layer feature." Set the distance to 500 meters and click OK. The number of bears within 500 meters of a stream will be highlighted.


Task Three

Find the suitable area for bear habitats based on the critiera from the first two tasks. Criteria: area must be within the 3 landcover types with the most bears and be within 500 meters of a stream.

Figure 5: To get the area within 500 meters of a stream, preform a buffer on streams. Open the ArcToolbox and navigate to Analysis Tools > Proximity > Buffer. The Buffer window will appear. The input features will be the streams feature class and distance will be set to 500 meters.

Figure 6: Next select by attributes on landcover by the three desired landcover types. Once they are selected an intersect can be preformed to determine the area that coincides with both the landcover and the streams buffer. Open the ArcToolbox and navigate to Analysis Tools > Overlay > Intersect. The input feature is chosen twice, streams and landcover are chosen (the selection of landcover is automatically used not the entire feature class). Clicking OK will produce the suitable habitat.

The dissolve tool can be used to remove the internal boundaries, resulting from the buffer and intersect tool operations, in the feature class of suitable habitats. Open the ArcToolbox and navigate to Data Management Tools > Generalization > Dissolve. Input features is the suitable habitat feature class. Clicking OK will make the suitable habitat feature class look more visually pleasing.


Task Four

Determine the area of suitable habitat that coincides with land owned by the DNR. The DNR wishes to use this land in part of their new bear management plan.

New provided data: dnr_mgmt feature class, study area feature class

Figure 7: To prepare the dnr_mgmt feature class, clip it by the study area, which is smaller than the extent of the dnr_mgmt feature class, and dissolve the internal boundaries in the data. Clip can be found in the ArcToolbox > Analysis Tools > Extract > Clip. Input features should be dnr_mgmt and clip features should be study area. Use the same process after figure 6 to dissolve the data.

Next use the intersect tool (location detailed under Figure 6) on the clipped, dissolved dnr_mgmt feature class and the suitable habitat feature class created in Figure 6. This will give the land that coincides with each feature class and can be given to the DNR.

Task Five

Exclude areas in the bear habitat feature class that are within 5 kilometers of urban or built-up areas.

New Provided data: landcover feature class (major_type)

Select by attributes the urban and built-up areas from the landcover feature class under major_type. Preform a buffer (detailed in Figure 5) on the selection of landcover.

Figure 8: After the urban areas are selected. Use the erase tool located in the ArcToolbox > Analysis Tools > Overlay > Erase. The input features should be suitable habitat feature class and the erase features should be the urban area buffer. This will erase the area of the buffer from the suitable habitat feature class.


Results

Figure 9: The final result. A map of suitable bear habitats that fit all the criteria, the area suitable for the DNR bear management plan, and all bear locations.

Lab 3: Multiple Criteria Query

Introduction

 This lab is meant to test students knowledge of attribute and spatial queries. Students will need to write multiple criteria queries to extract specific information from a database. Each query should be written as concisely as possible and return the correct information.


Methods

Boolean operators are used to create logical expressions that relate data together through satisfying combinations of conditions. For this lab, the Boolean operators AND, OR, and IN are used.

 AND - returns records that satisfies both conditions

Figure 1: In this diagram the red section symbolizes the records that satisfy the conditions. A and B symbolize different data sets.

 OR - returns records that satisfies either condition

 Figure 2: In this diagram the red section symbolizes the records that satisfy the conditions. A and B symbolize different data sets. 

IN - returns records that have one of several strings or values inside the parenthesis

EXAMPLE:              "STATE_NAME" IN ('Wisconsin', 'Minnesota')

In this example, all records from Wisconsin or Minnesota will be returned, but none from any other state.

Figure 3: Select by Attributes. The red area indicates the drop down menu to select the layer to use. The blue area indicates the drop down menu to select the selection method, either "Create a new selection" or " Select from current selection." The yellow area lists the fields of the data set and is also where the fields of interest can be chosen when constructing the query. The green area is where the query is entered through a combination of choosing fields from the yellow area, choosing the operators underneath the yellow area, and using the keyboard. For this lab, this green area is where the Boolean expressions are made.

Results

 - First Map -

- Second Map -

 - Third Map -

 - Fourth Map -

 

- Fifth Map -

 

 

Lab 2: Downloading and Mapping GIS Data

Introduction

This lab is meant to give students hands-on experience in utilizing on-line resources for data collection, specifically the US Census Bureau's website, and manipulating the data to be useful in GIS analysis. Completing this lab will showcase the students ability to download tabular data and shape files from the US Census Bureau's website, join standalone tables to attribute tables, create appropriate maps, and build visually pleasing layouts. Two maps will be generate through this lab. The first will be a population density map of Wisconsin and the second will display any chosen variable available to the student, downloaded from the US Census Bureau's website, concerning Wisconsin.

The US Census Bureau's mission is "To serve as the leading source of quality data about the nation's people and economy." They do this by attempting "To provide the best mix of timeliness, relevancy, quality, and cost for the data we collect and services we provide." Different data is collected at different time intervals; a population and housing census is done every 10 years, an economic census and government census is done every 5 years, and as of 2010 the American Community Survey is done annually. To learn more about the US Census visit their website here: About Us

The data that will be downloaded and utilized for this lab is "2010 SF1 100% Data" which is collected every 10 years. This data is the most basic of all census data and includes: total population, age cohorts, household size, racial breakdowns, housing units, relationships in households, and renter/owner occupied.

Methods

To begin, navigate to this website: American Fact Finder

Part I - Downloading Data

Figure 1: The American fact finder website. Click advanced search to continue.

Figure 2: The advanced search page. Click Topics to pick the area of interest. Here the data set can be chosen. Clicking the area of interest will place it in the upper left corner of the screen in the "Your Selections" box.

Figure 3: Next click on Geographies. Here the area of interest can be chosen. Clicking Add To Your Selections will place the area of interest in the "Your Selections" box.

Figure 4: Once the Topic and Geographies are chosen, the data set(s) can be chosen by filling in the box next to the name of the desired data set. Then click download.

The data will be downloaded as a .zip file. Extracting the contents will result in two excel tables. One is the metadata and the other is the census data. The census data has a field named GEO#id which will be used to join the data to a shape file that will be downloaded next.

Part II - Downloading Shape Files



Figure 5: In Geographies, click the map tab. This will bring up the shape file for the area of interest. Click the download button to open the Download window.

Figure 6: The Download window. Here options for which type of data should be downloaded are chosen. Shapefiles are at the bottom.

The shape file comes in a .zip format as well and will need to be extracted the same way as the data. The shape file can then be opened in ArcMap.



Figure 7: Here is the shape file displayed in ArcMap without any joins or symbolization. The excel table can also be seen in the Table of Contents.

Figure 8: The attribute tables for both the shape file (right) and the excel table (left) are shown. The GEO#id field in the excel table and the GEO_ID field in the shape file's table will be used as the foundations for a one-to-one cardinality attribute join.

Figure 9: Right click the shape file in the table of contents, hover over Joins and Relates, and click join. This window will appear. Chose the correct fields and table for the join and click OK.

Figure 10: This is the resulting table after the excel spreadsheet was joined to the shape file.

Figure 11: Right click on the shape file in the Table of Contents and select the symbology tab. Click the dropdown menu for Value to add the data to be mapped. Click the dropdown menu for Normalization if the data to be mapped needs it. In this case it does because the variable that is being mapped in population.

Results

 

Figure 12: The final output of the Lab. A map showing population density and a map showing household occupancy for the state of Wisconsin.

Lab 1: Coordinate Systems and Map Projection

Introduction

Lab 1 is meant to assess students knowledge of geographic and projected coordinate systems. Students should be able to define and project data to be usable for GIS analysis. Two maps will be generated through this lab. The first will be a comparison map of seven coordinate systems. The second will be a map of rivers in central Wisconsin meant to showcase the students ability to correct missing spatial references.

Methods

A geographic coordinate system (GCS)  uses a 3-dimensional spherical surface to locate features on the earths surface, commonly denoted with Latitude and Longitude. Using a GCS will result in distortions of one or more of the following: area, length, and angle.

A projected coordinate system (PCS) uses a 2-dimensional flat surface to locate feature on the earths surface. A PCS will show a target area without distortion but only for that specific area. The farther away from the target area, the greater the distortion.

Projected coordinate systems are based on Geographic coordinate systems. A GCS is needed to map a feature or area and a PCS refines the map to allow for accurate measurements and visualizations.

ArcMap 10.2 will be used to create the two maps needed for this lab. To illustrate what went into creating these maps, some basics of ArcMap will be described along with a short example walkthrough and different Tool descriptions.

 

- ArcMap Basics -

 



Figure 1: This is a Blank Map in ArcMap 10.2.

 

Figure 2: The Catalog window allows for quick and easy management of files. Click, drag, and drop a file into the workspace to add data to the map.

 

 

 

 Figure 3: The Table of Contents contains each data layer and it's associated data. Shape files and other data can be rearranged and modified from this window. What is seen in the Table of Contents is only a reference to the actual data, not the data itself. Therefore, any changes that are made are not permanent.

 

 

 

Figure 4: The Data Frame Properties is accessed by right clicking the Layers heading in the Table of Contents. Here general information for the data frame is displayed and different settings can be changed and modified for the entire data frame. Changing the coordinate system in the Data Frame Properties will only change how the data is displayed for that specific data frame, it will not change the individual files coordinate systems.

 

 

Figure 5: The Layer Properties window is accessed by right clicking a layer name in the Table of Contents. Here general information for the data in the layer is displayed and different settings can be changed and modified for that specific layer.

 

 

 

 

Figure 6: To add a data frame (picture on the left), click Insert on the main toolbar and choose Data Frame. The resulting New Data Frame (picture on the right) will appear underneath any data frames already created and will automatically be set as active.

 

 

- Example walk through -

 (importing data, selections, creating shapefiles)
 

Figure 7: The shape file states.shp was added to the workspace from the Catalog window. The data can now be modified and utilized in ArcMap.

 

 

 

Figure 8: To make a selection, click Selection on the main toolbar and choose either Select By Attributes or Select By Location. Here, Wisconsin will be selected by choosing Select By Attributes. 

 

 

Figure 9: The Attribute Table contains all the data associated with a file. It can be accessed by right clicking a layer in the Table of Contents. Here information can be gathered to fully utilize the Select by Attributes option.

 

 

 

Figure 10: After clicking the Select by Attributes option, the Select of Attributes window will appear.  Using the fields available and typing with the keyboard, the phrase, State_Name = 'Wisconsin', is entered into the bottom of the window (use single quotations when selecting text). Once Apply or Ok is clicked, the state of Wisconsin is selected in light blue.

 

 

Figure 11: Now that Wisconsin is selected it can be made into its own layer. Right click the layer the selection is referencing, hovering over Selection, then clicking Create Layer From Selected Features. This will create a separate layer with just Wisconsin.

 

 

 

Figure 12: The new Wisconsin layer is shown in a different color and placed above the layer that was used to make the selection.

 

 

 

 Figure 13: Now the layer can be exported as its own shapefile. This is done by right clicking the new Wisconsin layer, hovering over Data, and selecting Export Data....

 

 

 

 Figure 14: After clicking Export Data..., the Export Data window appears. Here the location of the new feature class is designated. When saving, the option for Save as type should be set to Shapefile.

 

 

 

 Figure 15: The resulting shapefile.

 

 

 

 - Tools for Projections -

(Define Projection and Project) 

 

 

Figure 16: The ArcToolbox (expanded on the left to show the location of projection tools used in this lab). The ArcToolbox can be accessed by clicking the toolbox icon on the main toolbar or can be found in the Catalog Window.

 

 

 

 Figure 17: Clicking Define Projection from the toolbox will result in the Define Projection Window. From this window, the feature class that needs defining is chosen along with its newly defined coordinate system. The Define Projection tool is used for feature classes that are missing spatial references. After the tool is run the feature class is now labeled correctly.

 

 

 

Figure 18: Clicking Project from the toolbox will result in the Project Window. From this window, the feature class that needs projection along with the desired new coordinate system can be chosen. The Project tool is used to change the coordinate system for a layer. Unlike changing the coordinate system for the data frame, this change is permanent.

 

 

 

Results

 

Using the skills and tools described above, these two maps were created.

 

Figure 19: Map comparing 7 different coordinate systems. The top most displays a geographic coordinate system, while the rest depict varying projected coordinate systems.

Figure 20: Map displaying the rivers of central Wisconsin along with a portion of Wisconsin. Both these files had projection abnormalities that were corrected by using both the Define Projection tool and the Project tool.