Exercise 4
Updating the City of Corvallis
Original author of
exercise: Greg Gaston, Department of Geosciences.
Used and further modified with his permission.
Introduction
Corvallis is a growing community and there was a desire to create a research park where new companies can locate and not have to build their own infrastructure (transportation and utilities). Sunset Research Park in southwest Corvallis was established in the 1980's. The park has grown from empty lots to more than a dozen commercial, educational, research and government buildings in the past 15 years. Because Sunset Research Park area is still growing the city needs to up date its GIS database every couple of years. You are tasked with updating and creating some new spatial data for the Sunset Research Park and a new shopping center, Sunset Shopping Center, recently completed to the west of park. You will create a map showing the location of new (since 2000) existing industrial/commercial buildings and their associated parking lots adjacent to Research Way and Technology Loop. There are rumors of new building regulations based on new wetland delineations. You will find the distance from each building and parking lot to the nearest wetland area using your map and tabular data then report your findings to your superiors.
New GIS skills:
The Data
You will need the following files for your analysis. The specific file names are in parentheses () below.
existing buildings (buildings.zip)
probable wetlands (wetlands.zip)
streets for reference (streets.zip)
streams for reference (streams.zip)
generalized boundary of the study area (study_bnd.zip)
air photos (digital orthophotographs) to identify new construction and parking lots (research_way.zip)
Files can be found on the class server (\\sci-geo\geo265\data\corvallis03). If you have previously mapped this drive it appears something like Geo265 on Sci-geo (S:)
Copy these files to your workspace. When you have completed copying all zipped files extract them with WinZip. You should have at least these shapefiles, MrSid images, and their associated (required) files:
study_bnd.shp
buildings.shp
wetlands.shp
streets.shp
streams.shp
12s5w3f_color_nw.sid
12s5w3f_color_sw.sid
12s5w4f_color_se.sid
12s5w4f_color_sw.sid
12s5w4f_color_ne.sid
12s5w4f_color_nw.sid
12s5w5f_color_se.sid
12s5w5f_color_ne.sid
12s5w8f_color_ne.sid
12s5w9f_color_nw.sid
12s5w9f_color_ne.sid
12s5w10f_color_nw.sid
Data were obtained from City of Corvallis, Public Works Department, 1245 N.E. Third Street, Corvallis, OR 97339. Color images are 6-inch pixel digital aerial orthophotographs taken April 29, 2002 and processed by 3Di West/GeoTerrra Mapping Group. 3400 West 11th Avenue, Eugene, OR 97402.
Projection: State Plane Oregon North (Lambert Conformal Conic)
Datum: NAD 27
Units: US feet
If you would like to explore the City of Corvallis FTP site for more layers and information go to ftp://ftp.ci.corvallis.or.us/pw/gis
Save your project often as you work through the following steps, otherwise you may lose hours of work.
Part 1
In Part 1 you will start a new project and add your newly acquired data to a view. Name your project EX4 <your name> .apr. Name the view something that reflects the area you are working with (e.g., Corvallis and Research_Way). You will create two new shape files and digitize the unrecorded buildings and parking lots along Research Way and in the adjacent Sunset Shopping Center.
Please DO NOT leave spaces in your chosen project name, theme names or shapefile names that you create, otherwise ArcView may get confused and not be able to locate your project and data again. For instance, do NOT save your theme to something named new buildings. Save it to newbuildings or new_buildings.
You will want to set both the map units and distance units of your view to feet.
Adding images to a view
Before adding images to your view you will need to add extensions that make it possible for you to view and process the images. From the File menu select Extensions... Then scroll down the list and check MrSid Image Support and TIFF 6.0 Image Support then click OK. Make sure your view is active and from the Theme menu select Add Theme. Change the Data Source Type to Image Data Source in the Add Theme dialog window. This will let you see available image files. Navigate to your workspace and add all of the images. Move around the images (e.g., pan and zoom) to view the extent and see the details when you zoom in.
Creating
an image catalog
(Read
about Image Catalogs in Help Topics > Index tab > search for image
catalogs)
These images are large files. Moving around (panning) and zooming in or out can be slow. An image catalog can improve displaying performance. Creating an image catalog requires running an Avenue script (a short program that performs a specific task). From the Project window activate Scripts and click on New. With the new script window active you should see a Script menu above the button bar at the top of the ArcView GUI. Select Script and in the drop down menu select Load Text File In the Load Script window navigate to c:\esri|av_gis30\arcview\samples\scripts and select imgcat.ave. Click OK. The script should now be loaded in the new script window. Next find the check button in the button bar and click this button. This compiles the program and makes it ready to run. When compiling is finished a button with a figure of a person running becomes active. Click that button to run the program. Select the view containing your images (if you only have one View in your project it is highlighted by default). Click OK. Name the catalog or keep the default name and click OK. The image catalog dbf file is added to your View (something like imgcat.dbf). With all of your images turned off, turn on the image catalog dbf theme. The images should reappear. Try to pan and zoom in. Do your images display faster? You may remove all the images from your view but keep the catalog. Next time you start your project see if you think it loads faster. If you do not see a noticeable change in performance turn off the catalog and load only the images you need to show the Research Way study area (12s5w4f_color_se.sid and 12s5w4f_color_sw.sid are the most important).
Add the rest of your data
Add the shapefiles buildings, wetlands, streams, streets and study_bnd. Zoom into the target area (Research Way runs primarily E-W, in the center of the image). Use study_bnd to locate the general area of interest.
Create new themes
The building feature theme does not include several large buildings that were evidently constructed after the photographs were taken. You will be creating a new theme into which you will digitize the missing buildings.
Under the View menu, select New Theme to add a new polygon theme to your data directory. This also means that you are creating a new shape file. Give this theme a name and color that you can recognize easily. Notice in the View Table of Contents that there is a dashed line around the check box for this theme indicating that it is in edit mode. Select the polygon drawing tool (NOT THE RECTANGLE one!) and trace the border of each roof that appears on the photo but has not already been digitized within the buildings theme (double click to complete a given polygon). When you are done, use the Stop Editing option under the Theme menu to save this theme.
Create another new polygon theme for parking lots (as there are no existing data for parking lots. You will digitize a shapefile with all parking lots on Research Way and Sunset Shopping Center).
You will now need to add some information to each building and parking lot so you will be able to identify them. You also need to add the topological information of area and perimeter. Open the attribute table for the building shapefile you have created. Under the Table menu, select Start Editing. Under the Edit menu, choose Add Field (this lets you add the columns to the table).
Add the fields (or items) ID and Name so that you can enter a sequential ID number and a unique name for each building polygon. For the field Name in the field Definition box, change the item type to String. For the ID field accept the default of Number as the type. Also, add the fields area and perimeter, accepting the default parameters for these fields. Consult the online help at any time for additional information and instructions.
Make the ID field active and then use the calculate tool to create the expression ID = rec. Notice that above the box is the beginning of the expression [ID] =. In the Field Calculator command box, type rec without the quotes. This command will place the internal record number for each record in the attribute table into the field build_id, thus allowing you to uniquely identify each building with a sequential number.
Click on the edit tool for changing cell values and update each record of the field Name. Please make up your own unique names.
Now you can use ArcView to automatically calculate the area and perimeter of each polygon! Select the area field in your table, as well as each of the records in that field (you can hold down the SHIFT key to select more than one thing at a time). Next, go to the field menu and choose calculate. You will have a formula box that will let you define a statement for performing the calculation area = . In that box, you need to specify
[Shape].ReturnArea
This will calculate the area value and display it in this field for each polygon.
Do the same thing to calculate the perimeter of each of your polygons. The perimeter = formula statement that you need is
[Shape].ReturnLength
When you are done editing your table you'll want to choose Stop Editing in the Table menu. At this point, your primary analysis has been to create new shapefiles of several buildings and parking lots.
Remember that if you save a shapefile, you will actually end up with at least 3 files that have extensions of .shp .dbf and .shx. You will have saved the critical and hard-to-replace information! These files are the core of YOUR work - make sure these data are secure (in other words, you might want to back them up to your zip disk or a CD)!
Part 2
Make your wetlands shapefile visible in the view. Note that the wetlands theme is a polygon shapefile and may be covering important information. You will need to make the wetlands theme transparent in symbology with some type of hashed pattern in order to view the themes below it. To do this you will change the Fill palette to a hashed pattern. You may also change the line width in the Fill Palette to 1 or 2. In the Color palette, change the background color to blank (the small box with the X in it) change the foreground color to a color of your choice and change the outline color to black.
Create a 100 foot buffer around the wetland polygons (wetlands.shp). First you will need to add a new to extension called XTools. This tool has many valuable tools for geoprocessing but for now you are only interested in buffering. You will need to make the wetlands theme active, then go to XTools, now in the menu bar, and select the Buffer Selected Features. Follow the wizard and make sure to:
When you display the results of the buffering analysis, make sure that the new buffer theme is underneath the wetlands theme and use symbology to make the buffers appear transparent if necessary.
Within the boundary of entire study area (study_bnd) identify the polygons (buildings) from buildings.shp that fall within this buffer zone. To avoid dealing with the entire buildings data set (almost 23,000 records) you can select and extract only those building of interest. With the buildings shapefile activated in your View select each building with the Select Feature tool (remember to hold down the shift key to make multiple selects). With all the correct buildings selected go to the Theme menu and select Convert to Shapefile..., enter an appropriate name and make sure you are saving to your work directory then click OK. This will create a new shape file of only those polygons selected. You will need to add ID and Name fields to the attribute table for this new shapefile as you did in Part 2 except for the ID calculation use ID = rec + 100. This will create numbers unique from those created in Part 2.
Now identify the building and parking lot polygons you digitized that also
fall within the wetlands buffer. It's up to you to figure out how best
to identify (name) the buildings and parking lots.
Write down the ID numbers for these identified buildings and parking lots
selected from each shapefile for future reference during your write-up.
Part 3
In part 3 you will retrieve parcel or tax lot data from the City of Corvallis GIS web site. Then you will add coordinate (x, y) data to a theme.
Add Event Theme
Add Event Theme is a useful tool for adding tabular coordinate data to a GIS.
Obtain parcel (parcel.zip) data from the City of Corvallis ( ftp://ftp.ci.corvallis.or.us/pw/gis/property). Unzip this file to your work directory and add parcels shapefile to a view. Explore the attribute table for this shapefile. Notice among the attributes the owners (Owner) of the properties are listed along with x and y coordinates (X_coord and Y_coord). These coordinates can be added to your view as points. Each point will be linked to it associated attributes.
Begin by opening Tables in the Project window and selecting Add. A list of .dbf files for each theme will appear from your working directory. If not navigate to your working directory on \\Sci-geo to view the databases. Select the file for parcels (parcel.dbf). Activate your View and from the View menu select Add Event Theme. The Add Event Theme window should have Table: parcel.dbf, X field: X_coord and Y field: Y_coord already filled in, if not, enter these values. Click OK. Parcel.dbf should appear at the top of your view as point data.
Explore the data
Make the parcel points theme active. Note that points have been added for the entire city and are located generally in the center of each parcel. With the Identify tool active click on one of the points along Research Way. The resulting table will display the attributes associated with that parcel. For the lots bordering Research Way, record the property owner for parcels with parc_id 12482, 12560, 12438, 12477 and 12568. Report these owners in your write up.
1. A layout including the following:
the new building and parking lot themes that you digitized along with the building theme.
the wetlands buffer theme
on your layout label the buildings and parting lots with the ID numbers of that fall within the 100-foot wetland buffer
the attribute tables for the newly digitized themes (building and parking themes) on a second layout with your name
Remember the six cartographic elements including your name!
2. Your lab write up, which includes:
3. Your lab notebook
The lab report along with the layout will be worth 20 points. The lab notebook will be graded credit/no credit.