DaTa EnTrY

I. Read Bolstad Chapter 4 and answer the following questions based on the reading and lecture.

1.       Would you have more problems with feature generalization and omission in large or small scale maps? Why?

·         Large scale maps cover smaller areas which usually results in less map generalization and omission. There would be more problems with feature generalization on a small scale map because there are more fused or aggregated features. Therefore more generalization and omission occurs. The few is not as clear on a small scale map.

2.       What is snapping in the context of digitizing? Why is snapping important (i.e. what does it help avoid)?

·         Snapping is the process of automatically setting nearby points to have the same coordinates. It relies on snap tolerance or snap distance. They are used to reduce undershoots and overshoots while digitizing.

3.       What is COGO and how does it relate to coordinate surveying?

·         COGO is a coordinate geometry that it is used to calculate the station coordinates. In other words, it defines a connected set of points from the starting station to a subsequent station. IT allows the calculation of coordinate locations form open or closed transverse(a series of connected lines that have a marked beginning and ending point. This is the way most coordinate surveys are done) Distance and angle measurements are combined with trigonometric formulas to calculate coordinates. The direct entry of COGO data leads to more accurate digital database than the digitization of cartometric maps. Many errors are avoided.

EXERCISE A

Q: What is the feature class type (point, line or poly) for springs? __point________

Geocoding

Ex16C



Lab #9b

More Practice with Spatial Analysis

Geog 206: Introduction to GIS

Fall 2010

Answer the following questions using both the attribute table querying and spatial analysis skills you have developed thus far. A geodatabase containing the data you will need to answer these questions has been provided for you in the Lab 9b Data link on Moodle. You may work in groups of two to answer these questions, but please make sure you each hand in your own copy of the answers.

LA_Urban



Provinces of Canada

 1.       How many counties does the State of Iowa contain? (1 pt)

·         99

2. Which county in Georgia contains the largest number of people, as of the year 2001? (1 pt)

·         Fulton

3. How many cities, with populations between 10,000 and 49,000, are located within the State of Washington? (1 pt)

·         31

4. How many miles long are all of the interstates in Los Angeles County? (1 pt)

·         4105.56

5. Simplify the UrbanBoundaries feature class so that only the urban areas of Los Angeles County are visible (Hint: you must use one of the overlay functions). Create a new feature class and save it into the LosAngeles dataset using the name LA_Urban. Include a screenshot of this new layer with your assignment. (2 pts)

6. How many acres of urban area lie within Los Angeles County, based upon your results from question #5? ( 1 pt)

·         Sum:      1441652.796875

7. How many zip codes have their centroid in Los Angeles County? (1 pt)

·         522

8. Create a layer displaying the provinces of Canada using the data provided to you in the Canada feature dataset. Save this new layer under the Canada feature dataset using the name Provinces. Include a screenshot of this new layer with your assignment. (2 pts)

9. Which Native American Indian Reservations lie within 75 miles of the City of Thurso in Canada? (1 pt)

·         Kitigan Zibi Indian Reserve

·         Akwesasne Indian Reserve 15

10. Open your final and complete geodatabase in ArcCatalog. Make sure all of the feature datasets and feature classes are viewable. Capture a screenshot of the geodatabase and include this screenshot with your assignment. (1 pt)

Introduction to Spatial Analysis

Geog 206: Introduction to GIS

Fall 2010

I.                    Read Bolstad Chapter 9 (pages 295-306 only) and answer the following questions based on reading and lecture.

1.      What is spatial scope and what are the three types? The extent or area of the input data that are used in determining the values at output locations. Such spatial operations are characterized as local, neighborhood or global. 

2.      What are the two types of Algebra used in queries?  Give an example of each.

Set Algebra:

Set Algebra uses less than<, greater than>, equal to, not equal to <>,to meet certain conditions or criteria’s.These are selections by attribute.The example given above identifies features that meet certain conditions using set algebra. On the map in the bottom left corner it shows a certain criteria, which is mapping out places with an area that are >= to 1000sq feet.

Boolean Algebra: 

What is show in figure 2 is an example of a Boolean algebra where it uses the conditions OR, AND, and NOT to select feature. The example circled above shows a type of Boolean algebra using not A or B. Meaning that the system will not choose A or B only C.

3.      What are the different types of spatial selection operations?

a.      By Attributes

1.      Set Algebra

2.      Boolean Algebra

b.      By Spatial characteristics

1.      Adjacency

2.      Containment

II.                  AFTER completing Ormsby Chapters 10 & 11, complete the following exercise.

§  Copy the Lab9a folder from Y:\courses_rmaas\Geog206\data to your working folder.

§  Open and explore the Lab9aData geodatabase.

4.   Is there a feature dataset in the geodatabase? ___yes_________

5.   What features classes are present? ___In the Los Angeles Data set we have three different feature classes. They are: PTDumeQuad, Vegetation and Wetlands. Within the personal geodatabase we have Wetlands_project._________________

Exercise 1:  Prepare (simplify) a vegetation layer for the Los Angeles region for further spatial analysis.

6.   How many features (records) exist in the Vegetation feature class in the Lab9aData.mdb geodatabase? __10896_____

§  To answer question 7, the vegetation layer needs to be simplified. Therefore, you need to dissolve the layer based on the “Covertype” field.  The resulting output feature class should be saved into the Lab9aData geodatabase and named “VegCov”. You’ll need to find the Dissolve tool based on what you’ve learned in lecture/Ormsby thus far.

7.   How many features (records) exist in the new VegCov feature class after running the dissolve operation? __9 records_____

§  The layer is still too large and unwieldy, so you need to clip it down to a smaller extent that only covers the Point Dume region.  Use the PtDumeQuad feature class to do this.  Name the output “VegCov_Clip” You’ll need to find the Clip tool based on what you’ve learned in lecture/Ormsby thus far.

8.   How many features (records) exist in the new “VegCov_Clip” feature class? ____8______

III.                Exercise 2: Generate a layer of Riverine wetlands that fall in the Point Dume quad.

§  Use the Select By Location tool to determine how many total wetlands have their centroid in the Point Dume quad.

9.   How many wetland features (records) were selected? _404____

§  Save the selected features to a 'virtual'/temporary layer using the Selection|Create layer from selected features tool.

§  Using the new layer you created, query out wetlands where the system is equal to Riverine.  (Hint: use the Systems field). 

10.   How many features (records) were selected? _123____

§  Export only these selected Riverine wetlands into a new shapefile named “Riverine_FirstInitialLastName”. Make sure to place this new shapefile inside your working directory for Lab 9a on C:/.  Ex. Riverine_rmaas.

§  Capture a screenshot (Alt PrtScr) of your final Riverine layer and paste it into this document.



Riverine



Riverine( Arc map screenshot)