GIS DATA COLLECTION, ENTRY AND ANALYSIS USING ARCVIEW GIS

Developed by Bob Slobodian - Malaspina University-College
Adapted by Lisa Keys-Mathews
Department of Geography
University of North Alabama
lmathews@unanov.una.edu

OBJECTIVES

·        Gather a limited set of data,

·        Enter the spatial data and develop an attribute database,

·        Develop an organization framework (database design) for the data,

·        Query the data and determine the operability of the combinations of the data, and

·        Create a limited GIS database and series of maps of a parking lot.

 CONTEXT

·        Data collection involves questions and analysis regarding:

·        Study Design

·        Quality Control

·        Data Verification

·        Completeness of data collection

·        Data Accuracy and Precision

·        For an analyst to truly understand the nature of GIS data and the inherent problems with data collection (quality, verification, etc.), it is necessary for them to gain "ownership" of the project and the data.  Collecting, entering, querying, analyzing and outputting geographic data provides students with an "ownership" that canned, pre-packaged data rarely does.

 OVERALL GIS PROCESS

·        State the Problem

·        What are you trying to do?  What questions are you trying to answer?  What problem are you trying to solve?

·        Design the data gathering phase of the project with the end product (answer to the questions) in mind.

·        The final product needs to integrate the spatial and attribute data with the idea of displaying spatial relationships.

·        Design the database such that you have enough information to answer the necessary questions.

·        Design the Database

·        What spatial data do I need to collect?

·        What attributes do I need to collect?

·        What format does the data need to be in?

·        Collect the Data

·        Determine the number of parking spaces in the assigned parking lot

·        Draw a sketch of the area and the parking spaces

·        For each parking space record the necessary attribute data (car make/model, color, car/no car, etc.)

·        Make sure all the data needed is collected (because the lot may change before you can get back)

·        Record you data in a tabular format for later use

·        Enter and Encode the Data

·        Open a new ArcView "Project"

·        Open a new ArcView "View"

·        Set the working directory

·        Create a new theme

·        Enter the spatial data

·        Prepare an attribute table including creating field names

·        Populate the id_no field with numbers 1, 2, 3, . . . ., n

·        Populate the remaining fields of the table with your data

·        Add text labels to the parking spaces

·        Analysis

·        Interrogate the spatial data to retrieve attribute characteristics (Identify button)

·        Interrogate the attribute data and display the associated spatial data

·        Query the spatial and attribute data (i. e., show me all the yellow, two door cars)

·        Create new data files from the queried data

·        Describe the Solution and Analysis

·        Write a description of what you determined from the analysis

·        Create output maps

·        Include any inferences you can draw from the information

·        Detail items that you would change if you had it to do over (Lessons Learned)

ARCVIEW GIS PROCESS

·        With your group design your database and then go collect data about the assigned parking lot.  

·        Start ArcView (use either the start button or the icon)

·        ArcView will open with a new project

·        Save the project as "Parking Lot"

·        Select "File" and drag down to "Save Project"

·        Open a New View

·        Click on the "View" icon in the project window

·        Click on the "New" button

·        A window titled "View1" will appear

·        Enlarge the windows by clicking on the "Enlarge" button in the upper right hand corner of each window

·        Name the View

·        Select "View" from the top menu bar and drag down to "Properties"

·        Name the view an appropriate name by highlighting the word "View1" in the top box

·        Provide your name as the creator

·        Map Units = feet

·        Distance Units = feet

·        Set the Working Directory

·        "File" . . . "Set Working Directory"

·        Create a New Theme

·        "View" . . . "New Theme"

·        Feature type = polygon

·        File name = spaces.shp

·        Notice that the theme is added to the Table of Contents, the on/off box is checked, and the on/off box has a dashed line around it (the dashed line means that the theme is editable, so you are ready to draw you map)

·        If the new theme is not editable, then go to "Theme" and "Start Editing"

·        Enter (digitize or draw) the spatial data

·        Select the graphics tool - rectangle

·        Draw one rectangle to represent one parking space

·        Pay attention to proportion and to the size of your drawing (note lower left hand corner for dimensions)

·        Continue to draw parking spaces (rectangles) until all of the spaces are drawn

·        Watch for "slivers" (holes between spots) and "overlap" (rectangles on top of another)

·        After all the spatial data is entered, select "Theme" . . . "Stop Editing" and select "yes" to save the edits. 

·        Notice that the dashed line is no longer around the on/off button - the theme is no longer editable

• Prepare an Attribute Table
• Click on the "Tables" icon or select "Theme"  . . .  "Table" to open the data table that is associated with the spatial data just created
• A field in an attribute table is a topic or attribute (car type, # of doors, color, etc.)
• A record equates to one parking space or polygon
• There should be one record in the table for each parking place (polygon) however if you created a polygon and then deleted it, there may be more records than spaces.  Delete the unnecessary records if this happens.
• Note that there are two fields - shape and id - and that the shape field says 'polygon' and the id field is '0'
• Make the table editable by selecting "Table"  . . . "Start Editing" (You must do this before you enter data)
• Notice that the field names are no longer italicized - this means that the file is editable
• Now you are ready to enter data

• Enter Data into the Attribute Table

  First, give each polygon a unique “id” identifier.  This helps the system keep the polygons apart.  To do this:

·        Select the edit tool from the menu bar – the cursor turns into a hand

·        Move the cursor over the first record in the table and single click.  Start numbering the records (polygons) from 1 until you reach the end.  Use the return key to advance to the next cell.

• Now add fields for the data categories collected.  To do this:

·        “Edit” . . .  “Add Field”

·        Name – Name of the category (i. e., color)

·        Type – this refers to the type of data to be entered

·        Number – width and decimal places

·        String – characters

·        Date

·        Boolean – True / False

·        Repeat this as often as necessary to enter all of the categories

• Populate the data table by selecting the “Edit” tool and typing the collected information

• “Theme” . . . “Save Edits” or “Save Edits as” allows you to save your changes and additions
• “Theme” . . . “Stop Editing” allows you to quit and save
• Save the project by clicking on the save button

·        Query the Attribute Data – Explore, Model, Solve a Problem

·        In the “Tables” window, select the “Query Builder” icon (the button has a hammer and question mark on it)

·        Double click on “ID” under fields, then click the > button and finally double click on the number 4 under values and choose “New Set”.  This will highlight all the records that have an ID greater than 4.  Notice that the corresponding records are highlighted in yellow

·        Switch to the “View” window and notice that the associated parking spaces are also highlighted in yellow.  This is an example of the “Live Link” between the attribute data and its corresponding spatial data.

·        Now query your data using one of your attributes (i.e., show me all the cars that are red)

·        Save these new queries as new themes.  To do this:

·        “Theme” . . . “Convert to Shapefile”

·        Give it a logical, descriptive name and save it to your directory

·        Add it back to the view

·        Save the project frequently

·        Conclusion

·        Create output maps from several of the queries you created.  To do this:

·        “View” . . . “Layout”

·        Select Portrait or Landscape depending on the shape of your data

·        Change the title by double clicking on the word(s)

·        Add a border by drawing a thick-line rectangle around the entire map