Lab 5

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:

http://archive.casil.ucdavis.edu/casil/remote_sensing/doq/doqq/

http://atlas.ca.gov/download.html#/casil/imageryBaseMapsLandCover/imagery/doq/doqq

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.





Lab 4

The following questions based on Bolstad Chapter 3, lecture, and Wikipedia.

1. What is an ellipsoid? How does an ellipsoid differ from a sphere?

An ellipsoid is a mathematical surface defined by revolving an ellipse around its minor (polar) axis. While a sphere is perfectly round an ellipsoid is slightly flattened. Due to this it is accepted as the best geometric model of the earth’s surface.

2. What is the imaginary network of intersecting latitude and longitude lines on the earth's surface called?

Geographic Coordinate System (GCS)

3. How does the magnetic north differ from the geographic North Pole?

The geographic North Pole is located on the northern pole of the earth’s axis of rotation. The magnetic north is where your compass points to. They are not located at the same place, and the angular distance between them is called the magnetic declination.

4. Why are datums important? Briefly describe how datums are developed.

A datum is a 3-D frame of reference that is used to determine surface locations. They have two major components. The first is a specified ellipsoid. Second, is a set of surveyed locations that specify positions on the Earth’s surface.

5. What is a map projection?

A map projection is a transformation of coordinate locations from a 3-Dimensional representation of the Earth’s surface to a 2-Dimensional one.

6. What is a developable surface?

A developable surface is a geometric shape that the Earth’s surface can be projected onto. Cones, cylinders, and planes are the most common surfaces.

7. Which lines on the graticule run north-south, converge at the poles, and mark angular distance east and west of the prime meridian?

a. Lines of longitude

b. The major axes

c. Parallels

d. Lines of Latitude

D. Lines of Latitude

8. Which of the following ellipsoids is now regarded as the best model of the earth for the region of North America?

a. Clarke 1866

b. International 1924

c. GRS80

d. Bessel 1841

C. GRS 80

9. Which well known coordinate system would be appropriate to use for developing and analyzing spatial data when mapping counties or larger areas? Why?

A universal transverse Mercator (UTM) coordinate system is most useful because is divides the world into zones that are 6 degrees wide in longitude, and can contain larger areas in one zone.

10. What is a great circle distance?

A great circle distance is a distance measured on the ellipsoid and in a plane through the Earth’s center.

Map projections are important to see, understand, and analyze spatial patterns. There are several surfaces to project a map onto, but the most common are a cylinder, cone, and plane. Also, some map projections do not use a developable surface. Instead they just use a mathematical projection from an ellipsoid onto a flat surface. Distortions can be expected when taking a three-dimensional object and projecting it onto a two-dimensional surface. These distort four main properties shape, direction, area, and distance. Different projections preserve different properties, and they are categorized based on what they preserve. There are three main categories of projections: conformal, equal area, and equidistant. Conformal maps try to preserve shape and direction. It does this by preserving the angles between curves. Two examples of this are a Mercator and a Gall Stereographic projection. A Mercator projection is a cylindrical map projection that keeps linear scale constant in all directions around any point. This preserves the angles, but it distorts shape and size as move from the Equator to the poles. This can be seen in map below. The countries are all where they are supposed to be, and they all have the right shape. However, the further from the equator you get the more out of proportion they become. Greenland appears to be larger than South American which is clearly not accurate. Due to this distance is not accurate either. It is approximately 6,211 miles from Washington D.C. to Baghdad, Iraq, but with the Mercator projection it is approximately 8,407.69 miles. Another type of a conformal projection is a Gall Stereographic projection. This too preserves angles, but it's projection is based off of a sphere. In the map below  you can see an example of a Gall Stereographic projection. Notice the similarities with the Mercator projection. The counties are the right shape, but still not the right size. However, in this example they are much closer to being accurate. This can be seen in the distance from Washington D.C to Baghdad, Iraq is only 5,938.71 miles. Another category of map projections is equal area. These maps preserve area. One example of this is a Mollweide projection (see below). Notice how the countries are now all approximately the proper size. For example Greenland is no longer larger than the other continents. However, now they are not necessarily the proper shape. One place where this is apparent is around the edges of the map. They countries all appear to be distorted giving it a slightly rounded appearance.  Since the map preserves area the distance between Washington D.C and Baghdad, Iraq (6,584.28 miles) is not that far from the actual distance. Another example of an equal area projection is a Bonne projection. This is a pseudoconical projection that preserves area, but not shape or direction. Looking at the map below it is evident that neither of these are preserved. Australia is highly distorted, and the overall shape of the world is more heart-like than ellipse-like. However, again the distance between Washington D.C and Baghdad, Iraq (6,016.27 miles) is not that far from the actual distance between the two cities. The equidistant projection preserve distance over a short area. Equidistant Conic projection is an example of this. Looking at the map below you can see that area, shape, and direction are all distorted. However, the distance from Washington D.C to Baghdad, Iraq is 6.266.72 nearly the actual distance between these two cities. A Sinusoidal projection also preserves distance as a ratio between the each parallel and the cosine of the latitude. Due to this the distance in the real world is smaller than the distance displayed on the map. For example the distance between Washington D.C and Baghdad, Iraq is 6,730.50 on the map, but is actually 6,211 miles in the real world. The other properties are still distorted as you can see in the map below.

Lab 3

1. What is a data model? Describe the two most commonly used data models.

A data model is a set of rules/constructs used to describe and represent aspects of the real world in a computer. The two most common types of data models are vector and raster models. Vector models consist of points, lines, and polygons. They are most useful in representing non-continuous data, such as a river, city, park, etc. Raster models define features as a set of cells in a grid. They are most useful in representing continuous data, such as elevation, pollution levels, rainfall, etc.

2. What is topology and why is it important?

Topology is the study of geometric properties that do not change when the forms are bent, stretched or undergo similar geometric transformations. They are important because they capture and record relationships between features. These may include adjacency, connectivity, and containment.

3. What type of data model would be best for representing hillside slope? Justify your answer.

A raster data model would be best for representing a hillside slope. This is because a slope has continuous changing data that would be very difficult to display in a vector model. Each cell in a raster model can contain the different elevations at that particular location, as opposed to having to draw contour lines.

4. Describe the relationship between spatial detail and cell dimension with regard to raster models.

Resolution is the relationship between spatial detail and cell dimension. The larger the cell dimension the lower the resolution, and the smaller the cell dimension the higher the resolution.

5. What are the four types of attribute data? Give an example of each.

The four types of attribute data are nominal, ordinal, interval, and ratio. Nominal data is descriptive/categorical data. An example would be mammals, birds, reptiles, etc. Ordinal data is like nominal data but it has some sort of rank or order associated with it. In college undergrad students are freshman, sophomore, juniors, and seniors. However, the amount of time they have spent in each category may vary from one person to the next. Interval data has ordered data and the differences between the values are constant, and zero is arbitrary. An example would be temperature (not including Kelvin). Ratio data is also ordered data, but it has an absolute data. Temperature measured in Kelvin fits into this type since it has an absolute zero.

6. List two types of vector data file formats.

Two types of vector data file formats are shapefiles and coverages.

7. List two types of raster data file formats.

Two types of raster data file formats are grids and images.

8. You can do all of the following in ArcCatalog EXCEPT:

a. Identify features

b. Copy data

c. Select features

d. View metadata

c. Select features

9. In the Chapter 4 exercises, does the World.mdb geodatabase contain a feature dataset?

No

10. What are the names of the feature classes contained in the World.mdb geodatabase?

Cities, countries, disapp_area, and world30 are the different feature classes.

11. What data format does the flight_path.lyr layer file reference?

It is referencing a shape file.

12. What are two ways to add data to an ArcMap document?

One way to add data to ArcMap is to click the add data button on the standard toolbar. The other way to drag the data from ArcCatalog

13. How many features (records) exist in the dissap_area feature class? How can you determine this using ArcCatalog?

There are 699 records for the dissap_area feature class. In ArcCatalog you click on the Metadata tab and then the Attributes tab. Under the attributes there will be details for disapp_area, and it lists the number of records.

14. Complete the ESRI online module “Basics of the Geodatabase Data Model” and post a screenshot of the certificate.

Lab 2

1. What types of software products are included in ArcGIS and which one will we be using most in this course?

 ArcMap, ArcCatalog, and ArcToolbox are all software products of ArcGIS. In class we will mainly be working with ArcMap and ArcCatalog.

2. Would it be better to perform most of your data analysis and layer symbolization in data or layout view? Why?

It is best to perform your data analysis and layer symbolization in data view. This is because in data view the various map elements (titles, scale bars, north arrows, etc) are hidden, and you can focus just on your analysis.

3. What are two ways to obtain help for ArcGIS Desktop?

 One way to obtain help for ArcGIS Desktop is to click Shift+F1. This brings up a What's This? tool that allows you to click on something and it will tell you about that feature. Another way to obtain help is to click F1. This brings up the main help window that you can find lots of information about the program. If you can't remember the keyboard shortcuts you can just click Help on the main menu and this will open a menu where you can choose what type of help you want.

4. How are attributes linked to geographic features?

Attributes are linked to geographic features by a unique ID called the OBJECTID.

5. What is the file extension of an ArcMap document?

ArcMap documents have a file extension called .mxd.

6. What are two ways to zoom in/zoom out on a map?

One way to zoom in is to click on the zoom in tool on the tools toolbar. Then click and drag a box around the area you want to zoom in on. This will zoom the display in on that area. One way to zoom out is to click on the full extent tool on the tools toolbar. The result of this will bring the map back to its original extent. The other way to zoom in/out is to click on the zoom in/out tool on the tools toolbar and click on the area you want to zoom in/out. The map will the center on where you clicked and either zoom in or out depending on the tool you have selected.

7. List three operations available in the ‘context menu’ of a layer. Hint: Right‐clicking with your mouse in the TOC should help you with this question.

Some of the operations available in the 'context menu' of a layer are open the attribute table, zoom to layer, and set a visible scale range.

8. If the check box next to a layer in the table of contents is grayed‐out, what does this mean? How would you resolve this issue?

A grayed-out check mark means that the layer's visibility depends on the map's display scale. In order to see the layer you need to zoom to the appropriate scale.

9. What are the differences between large and small scale maps? Provide an example of each.

A small scale map covers a large ground area, and a large scale map covers a small ground area. An example of a small scale map is a map of the world, and an example of a large scale map is map of a city.

10. Describe the differences between features and surfaces. Provide an example for each.

A feature is a geographic object in a layer. Examples of a feature include a river, city, park, lake, etc. A surface is a geographic expanse. The ocean layer is an example because it is a continuous expanse that changes with the different ocean depths.

11. A GIS is a useful problem‐solving tool. You can do all of the following tasks with it, except one. Which one?

a. Create project criteria

b. Query data

c. Display data on a report

d. Store project data

A GIS does not create project criteria. That is for you to do.

12. What are the minimum and maximum elevations of the cities Earhart visited? Briefly describe how you determined these values.

The maximum elevation was found in the city of Tucson in the USA, and the minimum elevation was at New Orleans in the USA. Their elevations are 1,045 and 0 respectively. I found this by right clicking "Cities Earhart Visited." The I clicked on "Open Attributes Table." In the attributes table I right clicked "Elevation" and clicked on "Sort Descending." This ranked the elevations from highest to lowest.

13. On the continent of Africa, what is the approximate distance (in miles) from Dakar to Assab? What are two techniques (one tool and one process) you could use to figure this out?

One way you can find out how far Dakar is from Assab is go into the attributes table for the flight path. Here it shows the distance between the cities that Earhart visited, so you just need to add up the distances between the different cities from Dakar to Assab. This gives you a total distance of 6901.167 km. Another way to find the distance between the two cities is to use the measure tool on the tools toolbar. Then you click on Dakar and move the mouse over Assab, and this will give you an approximate distance. The accuracy depends on what your scale is. The more zoomed in you are the more accurate it will be. Using this technique you get a distance of 6,707,110.99 meters.

14. What are two possible methods you could use to figure out the names of the cities shown on the map?

One way to figure out the name of the cities on the map is to move your cursor over the city. This will cause the name of the city to appear next to it. However, when you move your cursor again the name of the city will hide again. If you want to make the name of the cities appear permanently then you need to right click "Cities Earhart Visited" and click "Label Features."

15. Zoom to the extent of North and South America so that all the cities Earhart visited are labeled. Capture a screen shot (Alt + PrtScr) of this view and paste into your Word document (Ctrl+v). Turn in this screen shot with your answers from this sheet.

Lab 1b

1. Defining GIS

http://www.nwgis.com/gisdefn.htm

GIS (Geographic Information Systems) is a system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data. Practitioners also regard the total GIS as including the operating personnel and the data that go into the system. Spatial features are stored in a coordinate system (latitude/longitude, state plane, UTM, etc.), which references a particular place on the earth. Descriptive attributes in tabular form are associated with spatial features. Spatial data and associated attributes in the same coordinate system can then be layered together for mapping and analysis. GIS can be used for scientific investigations, resource management, and development planning.

GIS differs from CAD and other graphical computer applications in that all spatial data is geographically referenced to a map projection in an earth coordinate system. For the most part, spatial data can be "re-projected" from one coordinate system into another, thus data from various sources can be brought together into a common database and integrated using GIS software. Boundaries of spatial features should "register" or align properly when re-projected into the same coordinate system. Another property of a GIS database is that it has "topology," which defines the spatial relationships between features. The fundamental components of spatial data in a GIS are points, lines (arcs), and polygons. When topological relationships exist, you can perform analyses, such as modeling the flow through connecting lines in a network, combining adjacent polygons that have similar characteristics, and overlaying geographic features.

http://gislounge.com/what-is-gis/

GIS (Geographic Information Systems) is a technological field that incorporates geographical features with tabular data in order to map, analyze, and assess real-world problems. The key word to this technology is Geography – this means that the data (or at least some portion of the data) is spatial, in other words, data that is in some way referenced to locations on the earth. Coupled with this data is usually tabular data known as attribute data. Attribute data can be generally defined as additional information about each of the spatial features. An example of this would be schools. The actual location of the schools is the spatial data. Additional data such as the school name, level of education taught, student capacity would make up the attribute data. It is the partnership of these two data types that enables GIS to be such an effective problem solving tool through spatial analysis.

GIS operates on many levels. On the most basic level, GIS is used as computer cartography, i.e. mapping. The real power in GIS is through using spatial and statistical methods to analyze attribute and geographic information. The end result of the analysis can be derivative information, interpolated information or prioritized information.

http://searchsqlserver.techtarget.com/definition/GIS

A GIS (geographic information system) enables you to envision the geographic aspects of a body of data. Basically, it lets you query or analyze a database and receive the results in the form of some kind of map. Since many kinds of data have important geographic aspects, a GIS can have many uses: weather forecasting, sales analysis, population forecasting, and land use planning, to name a few.

In a GIS, geographic information is described explicitly in terms of geographic coordinates (latitude and longitude or some national grid coordinates) or implicitly in terms of a street address, postal code, or forest stand identifier. A geographic information system contains the ability to translate implicit geographic data (such as a street address) into an explicit map location. GIS developers sometimes obtain the map data from public sources or companies that specialize in collecting and organizing geographic information. The process of converting implicit geographic data into explicit or map-form images is called geocoding.

Geographic data can be stored in a vector graphics or a raster graphics format. Using a vector format, two-dimensional data is stored in terms of x and y coordinates. A road or a river can be described as a series of x,y coordinate points. Nonlinear features such as town boundaries can be stored as a closed loop of coordinates. The vector model is good for describing well-delineated features. A raster data format expresses data as a continously-changing set of grid cells. The raster model is better for portraying subtle changes such as soil type patterns over an area. Most geographic information systems make use of both kinds of data.

GISs do these kinds of things:

• They accept geographic input in the form of scanned-in and digitized map images. Often this data is supplied by a source that may own maps and has already digitized them.

• They rescale or otherwise manipulate geographic data for different purposes.

• They include a database manager, usually a relational database management system (RDBMS).

• They include query and analysis programs so that you can retrieve answers to simple questions such as the distance between two points on a map or more complicated questions that require analysis, such as determining the traffic pattern at a given intersection.

• They provide answers visually, usually as maps or graphs.

Similarities:

Looking at these three definitions some similarities can be noticed. A GIS (Geographic Information Systems) is system used to store, map, and analyze data. The data is spatial. This means that the data can be mapped using a coordinate system. Since GIS can be such a powerful tool it is seen in a wide variety of professions.

Differences:

Since GIS has several uses there are often differences in its definition. The first definition (http://www.nwgis.com/gisdefn.htm) mainly talks about the spatial aspects of GIS. Data within GIS have a particular coordinate system, and the data with the same coordinate system can be layered together and analyzed. Also, data can be "re-projected" from one coordinated system to another. When the data is "re-projected" to a new coordinate system the data should "register" or properly align. "Topology" is what defines the spatial relationships between features. The second definition (http://gislounge.com/what-is-gis/) refers more to the types of data stored in GIS. There are two types of data: spatial and attribute. The spatial data is where the data is located, and the attribute data is the additional information about the data. The example used in the definition is schools. The spatial data is where the schools are located, and the attribute data is any additional information that may be known about the school. The final definition (http://searchsqlserver.techtarget.com/definition/GIS) has to do with how the geographic data is stored. It can explicit, the geographic coordinates of the data, or implicit, such as a street address or a forest. When the implicit data is converted into explicit data it is called "geocoding". Data is also displayed in either vector or raster graphics. Raster models are best used for subtle changing features. While vector models are best used for well-delineated features.

2. Examples of GIS

http://www.depauw.edu/univ/gis/whatisgis.asp

Mortality Map of Heart Disease in White Males (1988-1992)

CDC/National Center for Health Statistics

Hyattsville, MD

This map was created using GIS to look at the heart disease of white males from 1988-1992. It was created by the CDC to analyze the distribution of heart disease cases nationwide.

http://latoyaegwuekwe.wordpress.com/

The Geography of a Recession

This is a really interesting video that shows the progression of the recession by county. It starts in January 2007 and shows the change in unemployment rates month by month. It is really scary to see how much black (10.0% or over) there is by the end. It is like a plague that is taking over the nation.

http://hvo.wr.usgs.gov/volunteer/gis/

Map of lava flows along Mauna Loa's northeast rift zone

Here is an example of GIS used to look at the lava flow along the Mauna Loa's northeast rift zone. This is a project by the Hawaiian Volcano Observatory.

3. Maps VS GIS

Although GIS is relatively new since it is a computer based program and maps have been hand drawn for several centuries, they are both a means of providing a user with valuable information. In addition, since they can be used to spatially display a wide variety of information they can be used in several fields. While GIS is a system that can create maps, it also stores, retrieves, and analyzes data. This data may or may not be found on the map. However, maps and GIS follow a similar idea: garbage in and garbage out. You may have accurate, interesting information, but if your display of it is poor you will lose your audience. GIS and maps are only as useful as the quality of the final product.