Lab5

What are some advantages and disadvantages of using digital spatial data?


 Some advantages of using digital spatial data is it possesses effectiveness  while being the quickest and easiest source of spatial information.

What are the most important questions you must ask before using already-developed spatial data?
Some of the most important questions someone might ask before using already-developed spatial data is it a reliable source. Will the data be efficient enough for processing information that is required. Is the data a cost effective source.

 How do DOQs differ from regular photographs?
 DOQs are scanned aerial photographic images with uniform scale. They consist of a one meter resolution with jpeg or tiff format. They are also used for updating data and for control points

 Choose three existing data sets and describe who produces them, what the source materials are and what they contain.
 The U.S. Geologic Survey are the producers of D.R.G,Digital Raster Graphic. which consists of a scanned image of the U.S.G.S. topographic map.
National Hydrologic Dataset is essentially the surface water module of the U.S map. The U.S.G.S. produces the NHD, which consists of information about the natural water and or constructed paths of water and the routes the take.The Geocommunity Data Depot is a data set that consists of all forms of GIS data. The Geocommunity are the one who produce the data and are made out for  public use. The GIS software is needed to use and layout the GIS data.



What is the difference between DEMs and NEDs?
NEDs are primary elevation source data product from the USGS DEMs.  It is a dataset that consists of the best available raster elevation of the U.S. DEMs, Digital Elevation Model and NEDs, National Elevation Dataset, are essentially working hand in hand.  10 meter resolution DEMs are what most of the NEDs are composed of.



 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, Hydrology

b. What are the names of the feature classes in the hydrology dataset?
NHDFlowline, NHDPoint, NHDWaterbody, Watersheds

c. For each one of the feature classes you just listed, describe whether it is a polygon, line or point layer.
 NHDFlowline: Line, NHD Point: Point, NHD Waterbody: Polygon, Watersheds: Polygon



. Using ArcCatalog, answer the following questions.
a. Is topoq24.shp a raster or vector layer?
Vector

b. What is the GIS data format of topoq24.shp?
Shapefile

c. Is there metadata associated with topoq24.shp?
Yes there is metadata associated with topoq24.shp

d. What is the GIS data format of the NHDFlowline layer?
Vector

e. Is there metadata associated with NHDFlowline?
Yes there is data associated with NHDFlowline

f. What are 3 keywords used to describe the NHDFlowline layer?
National Hydrography Dataset
g. Who created the NHDFlowline layer?
U.S. Geological Survey


.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 there is metadata associated with the layer.


 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.

 In the USGS_QD_ID field, find the value that corresponds to the Canoga Park QUAD_NAME. What is it? 34118-B5


 Load the DOQQ tiff into your Lab5 ArcMap document. Is the DOQQ black and white or CIR (color infrared)? The DOQQ is a CIR.