Transcript PowerPoint
Get Started with GIS Mapping Part 1of 2, September 2010 Madhu Lakshmanan Agenda for this section Brief introduction to GIS/mapping jargon Exploring Google Earth (GE) Point Maps versus thematic maps on GE Base Maps and where to find them The Census website AFF Mapper – Part 1 The Census KMZ Mapper Application Data Preparation – geocoding Mapping point data Resources/Homework What is GIS Mapping Wide spectrum of complexity Combination of hardware, software & data Can be one single large system or a suite of tools or one small tool depending on your requirement Data is key, design and color makes it more informative and appealing. Terms that we will come across Layer – A slice of the geography of a particular area. On a paper map, one layer could be the roads, another could be parks, another could be places of interest. Base Map – A layer that lends context to your data Geocoding – Converting street addresses into spatial data that can be displayed on a map (usually a latitude and longitude pair) Shapefiles – A data format that stores a particular geographic feature of a certain area. (it is usually a set of files) and is almost the de-facto standard. It is an ESRI-created format. KML/KMZ – an XML based language schema for expressing geographic visualization. It is an official open standard for all geobrowsers. Projection – transformation of a map from a spherical object (Earth) to a flat sheet of paper. Google Earth Toggle Sidebar Search Panel Places Panel Transparency Control Layers Panel 3D Viewer Navigation Controls Exploring Google Earth Copy Image/ Print Scr View Menu Tools – Options Navigation Fly to Layers Adding your own placemarks to a folder and saving a KML file Google Earth – some best practices Play, Practice, Patience Save as and keep your KML files organized in a separate folder on your drive. Clear cache regularly after saving required data Save without too many standard layers to keep kmz size down for emailing etc. Use transparency slider Actual screenshots are better than using the inbuilt GE copy tool – only copies the GE map and not any of your custom overlays Look at KML in free time – very much like XML. Point Maps versus Thematic Maps Point Maps usually give you information about a particular location on a map. They can be used for directions, descriptions and distance information among others. Thematic Maps reflect a particular theme (social, physical, political etc.) about a geographical area. It shows distributions in the form of shading or graphs rather than actual locations where people live. Point and thematic maps can be layered atop one another to provide a wealth of information. Example of a simple point map Location of major grocery stores in the Ann Arbor vicinity Example of a simple thematic map from the US Census Percent Population below poverty by county in North Carolina. Data Preparation - Planning Having some idea of what you want to achieve with your map What data do you have already? What data do you need to acquire? If you have to convert your data, what conversion tools do you need? What maps can you reuse? Data origin, metadata, processing Discuss with other users, colleagues, peers Base Maps Base maps or boundary maps help provide context to your data map. They do not contain any attribute information, they are just geography. They can be layered with the maps you create to give information that is not available or visible on the virtual globe (GE), such as county names/zipcodes etc. If your mapping concentrates on a certain region (state/county etc), you need to create your base maps just once and save them, and these can be reused as many times as you need. Example of a base map Zip code boundary map of New Mexico. Example of a base map County boundary map of New Mexico. Exploring the Census website http://www.census.gov/ TIGER/Line Shapefiles from census.gov Note that these are shapefiles and need conversion to kml/kmz to be used on GE. (AFF Mapper) Advantage is that they are the ones that most datasets are based on, so compatibility is great Download the shapefiles at the level you need, by drilling down to your state – county, MSA, zipcode etc. (Multiple files downloaded at the same time have an unzip problem, hence you need to do it one by one) Make sure you name your unzip folder meaningfully since things will get confusing after downloading multiple maps! AFF Mapper – Basic Created to make maps using census boundary files and American Fact Finder data Rule-based, but simple to follow Find a shapefile from http://www2.census.gov/cgi-bin/shapefiles/national-files This is a one time task for a particular geography, so make sure to extract, rename and save the file safely. Extract to a folder on your computer that you can find. There will be multiple files in the folder and they are all important. AFF Mapper - 1 Can be used for 2 purposes ◦ To convert shapefiles to KML for viewing on GE ◦ To combine shapefiles with data and converting to KML for viewing on GE. AFF Mapper - 2 Click on Input Shape – a browse window will open. Navigate to the base map folder that you downloaded and unzipped earlier and point to the shp file in that folder. Once that file is loaded, you will be able to see all the information in a tabular form – these are just geographical information and codes and identifiers. Ignore the “Join Tables Settings” panel for this exercise. In the Label Field column at the bottom, choose a field that will appear on the map, choose “Name” if there is such a field. Click Render. You can change the color at this point, but remember that you can also do it in Google Earth depending on other layers you are using, so just say OK with the default color. Click on Output KML and give it a name and location – very descriptive. I prefer to put it in the same folder as the shp file that was used to begin with. Hit Go and wait for the “Finished” message. You will now have your KML file available to open in Google Earth. The Census KMZ Mapper http://ctasgis02.psur.utk.edu/tokml/Default.aspx The Census KMZ Mapper Downloaded KML visualized in Google Earth Percent Population Without Access to Private Auto in Whole State Data Preparation - Geocoding Can geocode at different address levels like state, county, zipcode, complete address, etc. Multiple ways, differences in accuracy, daily limits, one time activity Using BatchGeocoder.com Using KMLGeocoder on desktop Zip data with lat/long for each state Mapping your case data - points Directly enter addresses into GE one by one. (can import bulk if using Pro version) Use a tool like KMLGeocode or batchgeocode.com to take your Excel address data and convert to KML directly – no identifying info needed other than address data and this can even be reduced to street level if you wanted to preserve some more anonymity. Limit is 5000 a day. GE shows a map with a scatter plot of your case data. A screenshot of this will not reveal any specific address information to a viewer but sharing kml will do that. Batchgeocode.com “Run” the geocoder and then Click on the “Download to KML file” button at the very bottom and you can have a saved file with the latitude and longitude information for your addresses. To-Do 1. 2. 3. 4. 5. Assemble a set of tools for mapping Begin a library of base files and data files for mapping on your computer/server Find sources of data for your region – many local governmental entities and health related organizations are good sources. Think about what sort of maps and visualizations work best for each purpose Discuss maps and mapping practices with peers. Resources and Interesting Mapping Applications - 1 NTAP GIS Resources http://lsntap.org/GIS_Resources_for_Google_Earth Census website http://census.gov American Factfinder http://factfinder.census.gov Google Earth User Guide http://earth.google.com/userguide/v5/ Rural Assistance Center Maps http://raconline/org/maps Show@/USA http://show.mappingworlds.com/usa Resources and Interesting Mapping Applications - 2 Download applications here http://lsntap.org/GIS_Resources_for_Google_Earth ◦ ◦ ◦ ◦ ◦ ◦ KMLGeocoder EarthPlot AFFMapper Shp2KML Statewise Geocoded Zip codes Regional Legal Aid boundary files Homework Familiarize yourself with Google Earth and also with the American Fact Finder part of the Census website Go to http://www.justice.gov/eoir/sibpages/ICadr.htm Pick any two states (try to pick atleast one with more than 1 entry!) and use Excel and batchgeocoder.com to plot those addresses on GE and save as a KML file. Send me a screenshot of your GE file when you are done (to [email protected]) Download County level and 5 digit zipcode level base maps of your state from the TIGER site and try to convert them to KML using AFF Mapper.