Creating a Map with ArcMap - Tufts University

More documents

Recommendations

Info

scale, you must be aware of the coordinate system and map units. These are accessible in the data frame properties. You can also give a name to a data frame (right now your data frame is called "Layers"). Accessing the Data Frame Properties • To access the data frame properties, right-click on the word "Layers" at the top of your Table of Contents and choose Properties. • Click on the General tab. • For Name, type in a name for your map (e.g., Someverville) • Note that for Units, the Map Units are likely designated as feet (grayed out) and the Display units are also set to feet (if you added the MassGIS data first, it might say meters). The Map Units are the actual units of the coordinate system in use - you cannot change these. The Display units can be changed - these are what appear if you measure distance on the map or are the default units for a scale when you create a map layout. Don't change the map units and return to your map. • Click on the Measure tool ( ) in the Tools toolbar. Click somewhere on the map to start a measuring line. Drag the line somewhere else and click again. You will see two measurements reported in the Measurement window. The first, segment, gives the distance (in Display units) of the line you just drew. The second, Length, gives the total distance. Click on a third point in the map. You will see the new segment distance plus the total distance of both segments. Double-click on the map to stop measuring (or choose a different tool). • Try changing the Display Units in the Data Frame properties (e.g., to miles) and use the measure tool again to see your measurements in your chosen units. • Go back to the Data Frame properties (right-click on the data frame name at the top of the table of contents). • Click on the Coordinate System tab - you will see that the data is most likely in the NAD_1983_StatePlane_Massachusetts_Mainland_FIPS_200_Feet1 coordinate system. Don't change anything here right now. We will discuss coordinate systems more in class because they are very important and can cause a lot of problems. But this is where you check or change coordinate systems of a data frame. Return to your map now. Drawing a map to scale • As long as the data frame has a known coordinate system, you can draw a map to scale by setting the scale in the scale area of the Standard toolbar: • Click on the 1:10,000 scale and view your results. Try other scales. You can also type in a scale yourself (you only have to type the denominator, e.g., 24000, no commas). These are unitless scales. 1:24,000 means that one unit on the map (or your computer screen) equals 24,000 of those same units in the real world. For example, one inch on the map equals 24,000 inches in the real 12
world, or 2000 feet. The scales provided are standard paper map scales in the United States. 1:24,000 is the map scale of the USGS topographic quadrangle maps (sometimes known as 7.5 minute maps because the cover 7.5 minutes of latitude and longitude). If you typed in 12000 in the scale box, you would be drawing a scale of 1:12,000 (1 unit onscreen = 12,000 units in the real world) which is the same as 1 inch = 1000 feet. Part 6 - Using digital orthophotos, scanned quad maps (DRGs), and shaded relief Aerial photos are another extremely useful data source in a GIS. To be useful in accurate mapping and a GIS, aerial photos are processed to take out distortions. This process is called ortho-rectification, and the resulting product is called an orthophoto. Unlike a normal aerial photo in which space is distorted, you can use an orthophoto to make measurements, just like you would with a regular map. Orthophotos for use in GIS also come with an additional file that indicates the locational position of the photo, so that it will appear in the correct location with your other data sets. Orthophotos can be very large files and cover relatively small areas. Many states and cities have them available online for download. In this section you will download orthophotos for Somerville. The orthophotos we will be using were created by the state of Massachusetts. The USGS has scanned and geo-referenced all of its 1:24,000 topographic quadrangle maps. These are called DRG's (for digital raster graphics). The maps for this area typically date from the late 1980s, but they can still be useful as topographic maps. They are also available online. Finally, we will also use a hillshade (shaded relief) raster data set originally from MassGIS. MassGIS shaded relief raster data is also available online, but we have prepared a smaller version covering the Boston metro area in the tutorial data set. (Note: the USGS has created shaded relief data sets for the entire country - these are available online through the National Map – http://nationalmap.gov/) Accessing and downloading orthophotos from MassGIS – using an index sheet Note: for this part of the tutorial, you must have a high-speed internet connection! Orthophotos, DRGs, and some other data sets are frequently tiled (split up) by using the boundaries of the USGS 7.5 minute quadrangle maps. So you need to know the mapsheet number or name to be able to find the correct data set for your area. MassGIS has an index GIS file that allows us to see which mapsheet number we need. In this example, we will use Somerville. • In your ArcMap session, click on the Add Data icon and navigate to the MassGIS \ Index folder and add OQMAIN_POLY.shp 13
Page 1 and 2: Creating a Map with ArcMap Revised
Page 3 and 4: one data layer at a time and press
Page 5 and 6: layers. If you copied your basemap1
Page 7 and 8: Part 3 - Drawing a layer based on a
Page 9 and 10: • Fill in the dialog box as you s
Page 11: • Make sure that the Label field
Page 15 and 16: Downloading image data from MassGIS
Page 17 and 18: • If the orthophoto is below the
Page 19 and 20: you later move or zoom, remember to
Page 21 and 22: frame you want). But in the layout,
Page 23: The ability to export to a digital

Creating a Map with ArcMap - Tufts University

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?