GEOG677 – Internet GIS University of Maryland at College Park
Lab Assignment 2 – Web Mapping with Google Earth, KML, and Google Map
Due Date: 01/05/2012
Overview This lab assignment is designed to help you explore the potential of Web mapping with some of the most popular tools (e.g. Google Earth, KML, and Google Map). The results will be published on your website and made available to anyone through the Internet.
This assignment is divided into five parts: Part I: Google Earth Part II: KML Part III: Using Google Earth to create KML Part IV: Using ArcGIS to create KML Part V: Creating Customized Web Mapping with Google Map
Data The GIS data to be used are as following (downloadable on the Blackboard): PG_Hospitals.shp PG_CensusTracts.shp
Part I: Google Earth
This section will help you get a better understanding about Google Earth and its capabilities. You will also need to install it on your computer in order to complete the tasks in later sections.
1. Getting to Know Google Earth
Google Earth is a virtual globe, map and geographic information program that has been developed and trademarked by Google, Inc. It is probably one of the most exciting and popular software in past few years.
Google Earth is an interactive mapping application that allows users to navigate the entire globe, viewing satellite imagery with overlays of roads, buildings, geographic features, and so on. It displays satellite images of varying resolution of the Earth's surface, allowing users to visually see things like cities and houses from a bird's eye view. The degree of resolution available is based somewhat on the points of interest and popularity, but most land (except for some islands) is covered in at least 15 meters of resolution.
Due to its nature, Google Earth is closely related to other geo-spatial technologies such as GIS and GPS. It can show all kinds of images overlaid on the surface of the earth and is also a Web Map Service client. Some people will go as far as claiming Google Earth is “People’s GIS” because of its popularity and free-to-use (almost). That’s why it is important to know some of the applications of Google Earth, especially when it comes to Web mapping.
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2. Downloading and Installing Google Earth
Google Earth is available under three different licenses: Google Earth, a free version with limited functionality Google Earth Pro ($399 per year), which is intended for commercial use. Google Earth Enterprise
For this class, it is perfectly fine to use the free version.
Your first task is to go to here and download Google Earth (V6): http://earth.google.com/
When installing, you can just follow the instructions on those pop-up windows. There is one step that will ask you to select setup type, make sure you check “Complete”.
3. Practicing Google Earth
Even though Google Earth provides state-of-art user interface, it still can be overwhelming to use it because there are so many buttons, menus, and options. Therefore, you may want to spend some time to read the User Guide (below) and do some testing. http://support.google.com/earth/bin/static.py?hl=en&page=guide_toc.cs
Part II: KML
KML refers to Keyhole Markup Language, which is a file format used to display geographic data in an Earth browser such as Google Earth, Google Maps, and Google Maps for mobile. KML uses a tag-based structure with nested elements and attributes and is based on the XML standard. All tags are case-sensitive and must be appear exactly as they are listed in the KML Reference.
1. Getting to Know KML
KML was developed for use with Google Earth. However, it can be displayed by many other applications including: Google Maps, Google Maps for mobile, NASA WorldWind, ESRI ArcGIS Explorer, Adobe PhotoShop, AutoCAD, Yahoo! Pipes, and so on.
If you are not familiar with KML, before you start next session, you might want to check out this KML tutorial: http://code.google.com/apis/kml/documentation/kml_tut.html
Also, you can even test some KML samples by using Google Earth which you have installed. The samples can be found here: http://code.google.com/apis/kml/documentation/KML_Samples.kml
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2. Creating KML
There are many different ways of creating KML files. Obviously, you can simply write KML codes just like HTML. And, you can also create KML files with Google Earth. In addition, you can create KML using some software such as ArcGIS. These last two options are the simplest way of creating KML because you don’t need to deal with coding. However, you may pay a price of not being able to control what exactly you want to do.
Now let’s try the first option.
The typical file structure of KML is as below:
The structure of this file breaks down as follows:
An XML header. This is line 1 in every KML file. No spaces or other characters can appear before this line. A KML namespace declaration. This is line 2 in every KML 2.2 file. A Placemark object that contains the following elements: o A name that is used as the label for the Placemark o A description that appears in the "balloon" attached to the Placemark o A Point that specifies the position of the Placemark on the Earth's surface (longitude, latitude, and optional altitude)
We can use the similar way of creating HTML to create KML.
Now, open NotePad and copy/paste those codes on previous page and then save it as a “.kml” file. Make sure the file extension must be “.kml” and the file name should contain your user ID.
I would suggest that you create a path – “Lab2/KMLs/” and save the file there. Other KML files will be saved there, too.
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After you save this file, you can double-click it to open. Google Earth should be automatically opened and the placemark (i.e. New York City in this case) will be displayed at the center of the map.
Now, you can change the placemark to some place which is more relevant to yourselves, for example, your home address or your favorite restaurant, etc. To do so, you will have to know the precise coordinates (latitude and longitude) of that location. There are a variety of ways of getting the coordinate. In this case, why don’t we let Google Earth do the work?
Here is an example: Let’s say I want to create a placemark for my favorite restaurant in College Park. The restaurant is Applebees and its address is: 7242 Baltimore Ave, College Park. First, I would open Google Earth. I will then type in the address in the Search bar and hit Enter. The globe will move and eventually display this point at the center of the map (see image below).
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Now, right-click the search result and select Properties.
Now, you can see the coordinates (see image on next page). Write them down and then replace the coordinates in the KML file you created earlier. Make sure the latitude and longitude match. Also, don’t forget the “-” sign in front of longitude.
Notice that the coordinates are in DMS (degree-minute-second) format. You will need to convert them into DD (decimal degree) format.
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Also, modify the “Description” in the KML file accordingly.
In the end, you KML should look like the one below. Make sure your user ID is part of the file name.
After I saved the KML file, I double-click to open it. The result is shown as below.
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Better yet, you can share your KML files in a variety of ways: you can e-mail them, host them locally for sharing, or host them publicly on a Web server.
In this case, we are going to use the Web. Once you've properly configured your server and shared the URL (address) of your KML files, anyone who's installed Google Earth can view the KML files hosted on your public web server.
For example, I have posted the KML I created on my website: http://www.terpconnect.umd.edu/~jma3/GEOG677/Lab2/
Or, you can refer to this example from last year: http://terpconnect.umd.edu/~dbarker7/html/maryland_gis_-_kml_experiments.html
Your task: You are required to modify the KML file that you created earlier by: (1) first selecting a location that you like; (2) obtain/convert the coordinates; (3) re-write the part of codes for Name/Description and coordinates within the KML file. Lastly, you will upload the KML file to the server and then create a link to it on one of your web pages.
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Part III: Using Google Earth to Create KML
You can also create Google Earth to create KML. This is actually easier because it does not involve coding.
Let’s assume that I want to create an application that can help some people find and get to know some of the most popular landmarks in DC area. In this example, I will just focus on George Washington University, the White House, and Washington Monument.
Start Google Earth.
Type in “George Washington University” in the search box and then find the location. Watch out the Ads added by Google.
Notice that there are already a lot of information about this entity. However, it is good enough. We can still add something new or different.
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Click on Add on the menu bar.
Then fill some information. For example, you can assign a descriptive name for the entity. You can even write an introduction about this entity.
By default, this entity will be displayed as a pin icon on Google Earth. Obviously, it is not specific enough. You definitely want to use customized image/icon to represent an entity of your interest.
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To do so, you can open the Properties dialog window.
Click on the push-pin icon next to the name box to open the icon panel.
From the panel list below, you can select any icon you like. However, you want to use the GWU logo.
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So, I would click on “Add Custom Icon…” at the bottom-left corner of the window.
There are two options to add this new icon: You can search on the Internet to find and save the GWU logo image file on your location computer. o You need to be careful when transferring the files to the server. Make sure the logo image is saved in the appropriate folder so that the KML file can find it on the server. You can add the logo image by using URL. o Make sure you use a link that is reliable, preferably from GWU web site. o This is a link that I have found. FYI. http://www.gwu.edu/portal/templates/template0008/YVQUaSfUSaZQdSRUdWX QZcRQbSWZdfRa/gwuLogo.gif
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Now, it’s time to create the KML file.
Note: Before you export these elements into a KML file, you will need to move them to Temporary Place folder.
To move them, you can simply drag/release each element into the Temporary Place folder. Then you will right-click on this folder and choose “Save Place As”. Save it to the same folder where you store the first KML file on your local computer.
Your task: You will follow the similar procedures and create a KML file for George Washington University, the White House, and the Washington Monument. You will need to use the customized images or logos. You will need to add your own descriptions for these three landmarks. Be sure to include the author’s name (i.e. you) at the end of description so that I know it’s your work. Make sure your user ID is part of the file name. Upload the KML files to the server and then create corresponding links on one of your web pages.
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Part IV: Using ArcGIS to Create KML
There has been some collaboration between Google and ESRI. One of the examples is that KML can be created with ArcGIS (i.e. ArcMap) and also be displayed by ArcGIS (i.e. ArcGlobe).
To create KML using ArcMap, there are two ways.
1. Creating KML with the Default Conversion Tool in ArcGIS
Add the two data layers – “PG_Hospitals” and “PG_CensusTracts”.
Change the symbology to make the map informative. The census tracts should be displayed based on the 2000 population.
Now, you are ready to export the data layers to KML files.
Expand Conversion Tools and then select “Layer to KML”.
Double-click to open it.
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Select an input layer and then define the output file name and its path.
Note: The file extension is “.kmz”. KML files are very often distributed as KMZ files, which are zipped KML files with a “.kmz” extension. When a KMZ file is unzipped, a single "doc.kml" is found along with any overlay and icon images referenced in the KML. It can be directly displayed in Google Earth.
Set the Layer Output Scale as “1”.
Click OK. It’s done!
If you double-click it, Google Earth will automatically open and then display this layer at the center. See image below.
Similarly, you will create a KML file from the “PG_Hospitals” layer.
Aftert the files are created, if you doule-click them, Google Earth will automatically oepn and display the two layers at the center. See image below.
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Your task: You will follow the procedures above and create two KML files (with .kmz extension). Make sure your user ID is part of the file name. Upload the KML files to the server and then create a link to each on one of your web pages.
2. Creating KML with the Extension Tool in ArcGIS
One of the drawbacks of using the default conversion tool provided by ArcGIS does not retain some more advanced symbology effects. So, it is only logic to look for a better way to create KML files using ArcGIS.
ESRI has a strong user community which has contributed to the development of numerous resources, tools, data, and information which are mostly free. One of such tools was designed to convert layers to KML.
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First, go to this website: http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=B49A0775-1422-2418- 34E1-EEA6DD9851BA
Once there, click on “Download”.
The script that we are going to download is Export_to_KML_V2_5_5. This is the latest version.
After unzip, read the Export_to_KML_documentation.pdf carefully. It needs extra steps to run it on Win7/Vista and ArcGIS 10.
Important! Before the installation, make sure you turn off ArcGIS.
After you have successfully added the button to your menu bar, you are ready to do the KML conversion.
Click on the button - , a window will pop up as below. Select the input layer.
In the case of hospitals, I want to have them labeled. So, I would select the attribute – “NAME” for labeling features. Make sure you save this KML file in the same folder as those previous KML files. Leave the rest settings as default.
Make sure the output file has your user ID as part of the file name.
Click OK. The KML will be created. At the same time, you have the option to open it in Google Earth right away.
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Your decision! Now, let’s do something different when we convert the layer – “PG_CensusTracts”.
What is we want display the population in 3D? Sure. It’s similar to Extrusion in ArcScene.
Click on the button - , define the input layer. Then select the attribute – “POP2000” to represent the height for the features. Check the small box in front of “Extrude features based on the height”.
Again, make sure you save this KML file in the same folder as those previous KML files. Leave the rest settings as default.
Make sure the output file has your user ID as part of the file name.
Notice that the file extension is “.kml”, compared to “.kmz” if you use the conversion tool from ArcToolbox.
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You can still do more.
Click on Options button. Another window will open. See image on next page.
You can define the KML layer transparency so that you can partially see through it. You can also write some description about the data layer.
There are actually more options to explore. You can be creative in this case.
Click OK and OK, it’s done!
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After you have created those two KML files, you can open them in Google Earth. The 3D and labels look great!
Your task: You will follow the procedures above and create two KML files. Upload the KML files to the server and then create a link to each file on one of your web pages.
Extra Practice: If you have Google Earth Pro, you may want to try to use the Movie Maker to create an animation. It should be similar to this example: http://www.kimberresources.com/properties-google-earth
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Part V: Creating Customized Web Mapping with Google Map
To be continued in Lab 3. But, you can see a simple example for this exercise from this link: http://www.terpconnect.umd.edu/~jma3/GEOG677/Lab2/HTMLs/GoogleMap_Test.html
Note: You have about 100MB storage space on the TerpConnect Server. Those KML files you will create are small and thus will not have any impact on your storage space on the server. When you choose customized images, make sure the file sizes are small. You may want to organize the files that you created in the same folder. You may want to create the links to those KML files on the same web page. This way, you will only need to send a single URL. Don’t wait until the last minute to work on this assignment because there might be not enough time considering tasks such as software installation. You cannot directly open KML files in Google Earth by clicking on the link on a web site. You will need to save them on your local computer first. To download a KML file, you must right-click it and select "Save Target As..." and then type a file name with the file extension ".kml". Meanwhile, you will need to set "Save as type" into "All Files". Otherwise, it will be automatically displayed or saved as XML file. On the other hand, you have the option to open KMZ files directly in Google Earth when clicking on the link.
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