GIS Topics And Applications Internetenabled GIS First Half Zoning

GIS Topics And Applications Internetenabled GIS First Half Zoning

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GIS Topics and Applications
Internet-enabled GIS
First Half
Zoning change analysis using Internet-enabled GIS
For the first half of the workshop, you will become acquainted with
locating GIS web services and adding them to ArcMap. You will use one
of the County websites to access parcel and zoning information and the
State’s imagery server for recent aerial photography. Using this data,
you will prepare a map that shows which properties you will need to
notify in your request for a zoning change. You will save selected
parcels to disk, however the rest of the data in your map should come
from a web GIS service.
G etting Started
In a new ArcMap document, open the Add Data window. In the past, you
have likely connected to a folder and accessed GIS data off of a disk.
In the root of the Add Data window, you will see several options,
other than the folders to which you have connected. One of the options
is GIS Servers. Double clicking on GIS Servers brings up a list of
previously connected GIS servers, along with wizards to help you
connect to ArcGIS, ArcIMS and WMS services.
If you have worked in New Jersey, it is highly likely that you have
used DEP’s i-MapNJ web mapping application. i-MapNJ is based on ArcIMS
technology and is configured to allow access using ArcMap desktop
software. Instead of using the web browser interface, we can access
i-MapNJ directly in ArcGIS. Open the Add ArcIMS Server wizard.
The URL of the i-MapNJ DEP ArcIMS service is:
http://njgin.state.nj.us/
Select the DEP image layer. You will notice that your Table of
Contents is now filled with all of the available layers in i-MapNJ.
Zoom in to a familiar area and explore. Turn sublayers on and off. IMS
image layers support basic attribute information transfer, so you can
use the Identify tool to view attributes.
The i-MapNJ application was never updated to include the new 2007
aerial photography. Turn off all of the sublayers dealing with aerial
photography in the iMap IMS layer. We will now add the state’s new
imagery server to our map. This server provides aerial photography
(1930, 1995, 2002, and 2007) and historic topographic maps. The
service is hosted by the Office of GIS at NJ OIT. NJGIN, the State’s
spatial data clearinghouse, has detailed instructions for adding the
service. This service is a Web Map Service, meaning that it will only
deliver map images and basic attribute information. In this case, map
images are all we need. To access the WMS service, you will start the
Add WMS Server wizard to connect to the server.
The URL of the state’s WMS server is the following:
http://njwebmap.state.nj.us/njimagery
Once connected, you will see several image layers are now available to
you. Select Natural 2007 and add it to your map frame. The projection
of the map frame is set to the projection of the first layer added to
the map. As the imagery is offered in several projections, you may
need to set your map projection to New Jersey State Plane. If New
Jersey looks wide and squished, select Data Frame Properties under the
View menu, and then select the Coordinate System tab. You can find NJ
State Plane under Predefined – Projected Systems – State Plane – NAD
1983 (Feet). After defining the projection, you will see that the
imagery layer changes slightly in shape. Many of the web services
available define multiple projections and any projections that the
server does not provide, the desktop software can supply.
O ur map now has a properly projected aerial photography mosaic
of New Jersey. Let’s now add parcels and zoning layers for Cape May
County. Again, click on Add Data and then GIS Servers. This time, we
will again use the Add ArcIMS Server wizard.
The URL for Cape May County’s ArcIMS Server is:
http://www.capemaycountyims.net/
Enter the URL, then click “Get List” to confirm that the URL is
correct. Clicking “Get List” sets the above radio button to “Just the
following service(s)” – reset this to “All services” and click OK.
You should now see Cape May County in your previously connected GIS
Servers, alongside the State imagery server. Explore the available
layers provided by the Cape May IMS server. We will be making a map
using parcels and zoning. Both of these are available in the CMParcels
image layer. Let’s add the image layer first. The layer from Cape May
is transparent; when overlaid on the aerial photographs you are able
to see both.
Zoom in to Ocean City, in the northeastern part of the county. As you
zoom in, you will notice that the roads now appear on the map. The
roads are scale-dependent, meaning that they will only draw when
zoomed in past a predefined point. You will also notice that the roads
are a deep blue. Blue is usually reserved for hydrologic features and
you may wish to change this on your map. You are unable to change the
symbology of features when using the image service, however you can
set the symbology for features when using a feature service. The
upside of the image service is that for a complex series of layers
offered as a service, the symbology is already defined, saving you the
time of setting the colors for all of the layers in the service.
Selecting Parcels
Let’s now add the CMParcels_Feature layer. This will allow us greater
functionality in performing our nearby properties analysis. Double
click on CMParcels_Feature and add just the Parcels feature. Now, with
each extent change, the software will make a request for the rendered
map image and all of the parcel features in the view extent.
Continue to zoom in to downtown Ocean City. If you’re unfamiliar with
Ocean City, we can zoom to the parcels in question directly. Open
Select by Attributes and select the Parcels sub-layer from the
CMParcels_Feature IMS layer. Remember, make sure you are selecting
from the Parcels feature and not the attributes of the parcels in the
rendered image.
The properties are Block 907, Lots 1 through 5. The SQL statement that
will select all five properties is:
BLOCK = 907 AND (LOT = 1 OR LOT = 2 OR LOT = 3 OR LOT = 4 OR LOT = 5)
Note: The actual field names are longer and omitted above for clarity.
Use the Select by Attributes window to recreate this statement in
ArcMap. Don’t forget the parenthesis around the LOTs, as you’re only
selecting lots in block 907.
Once you have your five parcels selected, export them as a shapefile.
Right click on the Parcels sub-layer in the Table of Contents and
choose Export Data from the Data flyout menu. Export just the five
selected parcels. Save it to a temporary folder on your hard disk or a
USB drive, if you have one. When prompted to add this new layer to the
map, do so. You can also change the name of the layer to “Properties
in Question.”

We now need to identify the parcels within 200 feet of our properties.
Open Select by Location and select features from the Parcels IMS
features that are within a 200’ distance from the parcels you
previously selected and exported. The selection should result in 52
parcels, which includes the 5 parcels you previously selected. Export
this selection to another shapefile in the same location as you
previously exported.
You can now continue to make your map of properties that will need to
be notified in this request for a zoning change. Set symbology for
your two shapefiles to differentiate between the parcels requesting
the zoning change and the parcels to be notified. If you so desire,
you can also buffer the five parcels to create a polygon that shows
200 feet from the extent of the five properties. Switch to Layout View
and add the necessary map elements (title, legend, scale, etc.) and
export your map as a PDF file.
A PDF is great, but the majority of users will not be able to layer
additional data on top of your PDF map. They will not be able to
determine a location on the PDF using latitude and longitude. A PDF is
simply a map image without additional geospatial data.* What we need
is a format that can function as a GIS data container with symbology
information to turn that data into an interactive map. We will use KML
as that rich data container.
*There is a GeoPDF extension to the PDF specification that would allow
layered GIS data to be contained within the PDF file. However, the
adoption rate of this software is currently far lower than that of KML
viewers such as Google Earth.
Second Half
Distributing Maps Using KML
In the second half of the workshop, you will export your data from
ArcGIS to KML. You will learn how to make the most of the KML format
using ArcGIS. You will also explore using WMS services that are
wrapped in KML. Bring your parcels into SketchUp and build some basic
3D models that you can include in your KML file.
Getting Started
Open your map from the first half of the workshop. Make sure you have
defined transparency and symbology for your two layers.
Exporting a Layer to KML
ArcGIS has two tools for converting GIS data in ArcMap to a KML file.
With other datasets, you might be inclined to convert between formats
using ArcCatalog. With KML, you will use ArcMap because KML includes
symbology information within the file format. Exporting from ArcMap
ensures that your KML looks like the data as you see it in ArcMap.
Open ArcToolbox by clicking on the red toolbox icon. Under the
Conversion Tools toolbox, locate the Layer to KML toolset. Within the
To KML toolset, you will find two tools, Map to KML and Layer to KML.
Both tools export data from ArcMap to KML. We will work primarily with
the Layer to KML tool in this exercise. Open the Layer to KML tool.
The tool requires three pieces of information in order to function:
the layer to convert to KML, the output KML file, and the scale. The
output KML will be created once the tool is run, you do not need to
create a KML file beforehand. The scale should be set to a value close
to the scale at which you made your final map. Any scale-dependent
features (line widths, point icons, etc.) will be drawn and scaled
based on the scale you choose. The scale is input as only the
denominator of the representative fraction, for example, a map scale
of 1:24,000 would be entered as 24000.
Our KML file should have both the Properties in Question, as well as
the Nearby Properties. Layer to KML only allows for one layer to be
exported at a time. There is a simple workaround for this problem.
Within the Table of Contents, hold the control key and click the names
of your Properties in Question layer and your Nearby Properties layer.
When both names are highlighted, right click and choose Group. This
will make a group layer that can be passed to the Layer to KML tool.
Reopen the Layer to KML tool and export your group layer. Set the
output to the same workspace that you stored your shapefiles. Set the
scale to something close to what you have in ArcMap. 2400 will work.
Once you have created your KML file, locate the file in Windows
Explorer (i.e. My Computer) and double-click it to start Google Earth.
Once your KML loads in Google Earth, give it a quick review. Do the
exported features look like what you had selected in ArcMap? Colors
and transparency are preserved in the export, however, there may be
some issues you will want to correct before distributing your KML file
to your associates.
*
You may have some overlap in the two layers from the Select by
Location analysis.
*
Your data does not include any attributes about the layers or the
features within.
*
You want to use the NJ aerial photography instead of the aerials
Google provides.
Let’s remedy each of these issues before moving on.
Removing Overlapping Polygons
Our Select By Location analysis selected the five parcels from the
Properties in Question layer when we made our Nearby Properties layer.
ArcGIS was logically correct in doing so – they are within 200 feet of
themselves – however this is not what we would want to show.
Temporarily hide the properties in question layer by unchecking the
box next to its name in the Table of Contents. Use the Interactive
Select Features tool to select the five duplicate parcels in
our Nearby Properties layer. An alternative to this is to use Select
by Location again, selecting the parcels in Nearby Properties that are
identical to those in Properties in Question. You may also want to
select the long railroad property that is now a de facto right-of-way
for deletion. Once you have the features that you wish to delete
selected, you can run the Delete Features tool on the layer to remove
just the selected polygons. Within ArcToolbox, locate the Data
Management Tools toolbox, and then the Features toolset. Delete
Features accepts only one variable, the name of the layer in which you
wish to delete features. Be careful – passing a layer to Delete
Features with no selected features within will result in the deletion
of all features in the layer.
Including Attribute Information in Exported KML
ArcGIS 9.3 included a new tool in ArcMap. The HTML Popup tool allows
you to interactively click on features, resulting in an HTML formatted
window with attribute information. Initially, this may seem like a
secondary implementation of the Identify tool, however it is
extensible and is the key to implementing popups in Google Earth from
KML generated using ArcMap.
O pen the Layer Properties for your Properties in Question
layer and switch to the HTML Popup tab. Check the Show Content
checkbox. Under Display HTML formatting, select As a table. Click the
Verify button to get a preview of the HTML content. You will notice
that the long field names from the IMS Server have been shortened and
are now incredibly ambiguous. Click Apply to save the changes thus far
and switch to the Fields tab. The Fields tab allows you to hide fields
from being shown in the Attribute Table, Identify window and the HTML
Popup. Hide all the fields except for “CAPEMAY_5” and “CAPEMAY_6” as
these fields correspond to Block and Lot values. Under the Alias
column, change the alias for “CAPEMAY_5” to “Block” and the alias for
“CAPEMAY_6” to “Lot”. Click Apply, switch back to the HTML Popup tab
and hit verify again. You will now notice that the window shows just
the Block and Lot attributes from the data. Close the Layer Properties
window by clicking OK.
Select the HTML Popup tool from the Tools palette. You will
notice a thin blue line around the features in your Properties in
Question layer. Click on one of your features and you will see the
HTML popup window appear. When you export this layer (by itself or as
part of a group layer) to KML, this functionality will be exported as
well. Clicking on exported polygons in Google Earth will produce the
same window.

You can also include additional information about your layers in the
exported KML. Reopen the Layer Properties and switch to the General
tab. The Layer Name will become the folder name when exported to KML.
The Description will appear in the Places sidebar and will also be
available as an HTML popup for the entire folder. Ownership or source
information should also be entered into the Credits field, as that
will also transfer to the KML file.
Bring Your Own Data
Currently, the aerial photography provided by Google for Ocean City is
from the NAIP program. This data is a lower resolution and older than
the 2007 NJ aerials. We are in luck, because the New Jersey aerial
photography can be brought in to Google Earth and packaged with your
KML, ensuring that your users have the same base data.
In Google Earth, select Image Overlay from the Add menu. Name the
layer “NJ Aerial Photography” and switch to the refresh tab. You will
notice in the lower right there is a WMS Parameters button. Using
image overlays, you can add a WMS layer to Google Earth. Before we
configure the WMS service, let’s define how frequently we want to
update the WMS layer. Set View-Based Refresh to 4 seconds After Camera
Stops. The View Bound Scale should be set to a value between 1 and
1.25. This refers to the scale of the requested WMS image compared to
the current extent of the map view. Once we have the refresh options,
let’s open the WMS Parameters window. The WMS server will be the same
WMS server as before:
http://njwebmap.state.nj.us/njimagery
You will see that Google Earth recognizes the same set of layers that
were available in ArcGIS. Select just the Natural 2007 layer and add
it to the list of selected layers. Add only one layer at a time – each
of these layers are opaque and requesting multiple layers when only
one will be visible would put undue stress on the server. Close both
the WMS Parameters window and the New Image Overlay window by clicking
OK.
You should now see your new Image Overlay in the Places sidebar. Make
sure the image is below the folders containing your exported polygons,
but within the KML Folder. If your exported polygons are not visible
when the NJ aerial photography is switched on, it is due to a drawing
issue in Google Earth. Open the Properties for the Image Overlay and
move the Transparency slider just slightly to the left until the
polygons reappear. They should reappear well before the Image Overlay
is noticeably translucent.
By right clicking on the KML Folder, you can save the folder and all
data within to a new KML file. The WMS-supplied image overlay will be
saved along with your polygons. You can now send this KML file to
others and they will be able to see your exported KML and the NJ
aerial photography.
Going Further with 3D Models
Google acquired SketchUp, a lightweight 3D modeling application that
has become tightly integrated with Google Earth and KML. We can use
SketchUp to quickly add some basic volumes to represent buildings in
the area.
Open Google SketchUp. From a blank SketchUp document, we can import
the current view in Google Earth as a basic canvas on which we can
begin drawing. Locate the Get Current View button and click it once
you have centered Google Earth on your focus area. The view from
Google Earth is now available in SketchUp. Despite it being black and
white, the view still contains your exported features, along with the
NJ aerial photography, provided both layers were switched on in Google
Earth at the time of import.
Begin sketching features on the imported view. If you are unfamiliar
with Google SketchUp, there are some tutorials that can help you
orient yourself in the software. Once you are happy with your 3D
model, locate and click the Place Model button. Your 3D sketch will
now appear in Google Earth, alongside your exported KML. SketchUp has
the ability to save models as standalone KML files, however you can
easily drag the exported 3D model from its folder in Google Earth to
your KML folder, allowing you to save your model in the same file as
your polygons from ArcGIS and your WMS image overlay.