I. Answer the following questions based on Bolstad Chapter 7 and lecture.
1. What are some advantages and disadvantages of using digital spatial data?
Many spatial data exist at low or no cost, it is the easiest, quickest and least expensive source of spatial information, and data is collected more frequently in digital formats to provide efficient processing are some of the advantages to using digital spatial data. Some disadvantages include the need to analyze the data before using it to make sure it is appropriate for your needs, it may not be up-to-date, and depending on the area you are looking at it may be a lower resolution.
2. What are the most important questions you must ask before using already-developed spatial data?
Does the data provide the necessary information, detail, and accuracy for the given area?
3. How do DOQs differ from regular photographs?
DOQs are georeferenced.
4. Choose three existing data sets and describe who produces them, what the source materials are and what they contain.
1) http://seamless.usgs.gov – This is provided by the USGS, and they offer national land cover data and digital elevation models.
2) http://ec2.usgs.gov/geodata/index.php - This is provided by the USGS, and they offer digital line graphs.
3) www.fws.gov/nwi - This is provided by the U.S. Fish and Wildlife Service, and provides a national wetland inventory.
5. What is the difference between DEMs and NEDs?
NEDs are a combination of DEMs for the United States. The used the highest-resolution DEMs and are combined seamlessly.
II. Step through the following instructions and answer any associated questions.
1. Launch ArcCatalog and navigate to the T drive. Copy the following GIS data down to your Lab5 folder on the C drive (or U, Z, I, etc.).
a. USGS 1:24,000 Topographic Quads: T:\\gis_data\usgs\quad_grids\topoq24.shp
b. LA County Landuse: T:\\gis_data\miscellaneous\socal_landuse_2000\Los_Angeleslu_2k\lacounty_lu01.shp
2. Go to my folder for Geog206 on the Y drive and copy the Lab5Data.mdb geodatabase down to your Lab5 folder. Explore the geodatabase.
a. What are the names of the feature datasets in the geodatabase?
Basemap and Hydrology are the two feature datasets.
b. What are the names of the feature classes in the hydrology dataset?
NHDFlowline, NHDPoint, NHDWaterbody, and Watersheds are the four feature classes.
c. For each one of the feature classes you just listed, describe whether it is a polygon, line or point layer.
NHDFlowline - line layer
NHDPoint – point layer
NHDWaterbody – polygon layer
Watersheds – polygon layer
3. Using ArcCatalog, answer the following questions.
a. Is topoq24.shp a raster or vector layer?
Vector layer
b. What is the GIS data format of topoq24.shp?
It is a shapefile.
c. Is there metadata associated with topoq24.shp?
Yes
d. What is the GIS data format of the NHDFlowline layer?
It is a geodatabase format.
e. Is there metadata associated with NHDFlowline?
Yes
f. What are 3 keywords used to describe the NHDFlowline layer?
Hydrology, Stream/River, Lake/Pond are all keywords used to describe the NHDFlowline layer.
g. Who created the NHDFlowline layer?
Earth Science Information Center, U.S. Geological Survey created this layer.
4. Export the NHDFlowline feature class to a shapefile format, name it NHDFlowline.shp and place in the Lab_5 folder on your C-drive.
a. Is there still metadata associated with the layer?
Yes
5. Open ArcMap and load the following layers. topoq24.shp, CountyBoundaries, Highways and lacounty_lu01.shp. Save the ArcMap document in your Lab5 folder and name it Lab5.mxd.
6. In the next step, you will use the topo layer to figure out which DOQQ to download from the CASIL website so that you can view the CSUN campus.
a. In ArcMap, open the attribute table for topoq24.shp.
b. In the USGS_QD_ID field, find the value that corresponds to the Canoga Park QUAD_NAME. What is it?
34118-B5
c. Click on the following link:
d. Use the first 5 digits of the USGS_QD_ID value to figure out which folder to go into.
e. Once in the folder, you want to download the canoga_park_ne DOQQ.
Note: You can sort the quad names by clicking on the Description field.
Note 2: For each DOQQ you download, you will need the .tif, .tfw AND .tif.xml files.
f. To download: Right-click on each file separately and choose Save Target As. Make sure you save to the Lab5 folder on your C-drive.
7. Load the DOQQ tiff into your Lab5 ArcMap document. Is the DOQQ black and white or CIR (color infrared)?
Black and White
8. Use the DOQQ and Highways layer to find the CSUN campus. Zoom to that location. Capture a screenshot (Alt+PrintScreen) and paste into a Word document with your other answers for this assignment.
9. Save your Lab5.mxd document and close ArcMap.
10. In ArcCatalog, navigate to your Lab5 folder. Capture a screenshot (Alt+PrintScreen) of the expanded folder/file structure and paste into a Word document.
11. In ArcCatalog, navigate to the Lab5 folder and rename lacounty_lu01.shp to La_Landuse.shp. Note: You will not be able to do this if ArcMap is still open.
12. Open the Lab5.mxd document again.
a. What happened to the lacounty_lu01.shp layer?
It now has a red exclamation mark next to it.
b. Fix the problem by redirecting the layer to the new data source name.
Right click the layer and go to properties. Under the Source tab click set data source, and redirect it to the new data source name.
13. Save the ArcMap document and exit.
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