Downloading Images and Digitizing Features Using a GIS - Answer Key

Author:  Joseph J. Kerski, USGS, jjkerski@usgs.gov, 303-202-4315

1) [ 7/1/98 ]

2) [ .tfw ] 

3)  [10/04/97]

4) [ 2 files ]

5)  [ 2 files ]

6)  [ It would not be recognized as a Header file and would not georegister ] 

7)  [ 2 meters ]

8)  [ 1 meter ]

9)   [ I had a problem getting the correct coordinates to display. The header file had a .txt extension, which did not display until I unchecked the "Hide file extensions" box under Tools-->  Folder Options-->View in Windows Explorer.  Then, I renamed the Header file by removing the .txt] 

10)  [ DRG ]

11)  [ DOQ ] 

12)   [ 1:1293 in DRG     1:2264 in DOQ ]   (Answers may vary )

13)  [ No ]

14)  [ There is no attribute table associated with the image ] 

15)  [ These images were created before the buildings existed ] 

16)  [ Polygons ] 

17)  [ no ] 

18)  [ 3 ] 

19)  [ The 3 records represent the 3 polygons that were digitized ] 

 20) [ no ] 

21)  [ square meters ] 

22)   [ multipurpose center]

23)  [ 2448.28 Sq Meters -  Size will very depending on how the building was digitized.]

 24)  [ 2 fields – Name & Size ]

 25)  [ 2 fields – Shape & ID ] 

26)   [ Name ].  

27)   [ line ] 

28)   [ view -->  new theme. Choose type = line. Click on the last tool bar

       button. Choose the zig-zag line. Digitize each road by clicking the

       pointer at on end, clicking at each bend of the road, and double

       click at end of the road.  A record will be created in the table for

        each road digitized. Then, with the road theme activated,

         Table –Start editing. Edit à Add field. Do this for each field

         to be added. To fill in values for the new fields, click on the text

         edit tool and you can then tab through the table entries, keying

         in the field values. ]                    

29)  [ Digitizing the road was similar to digitizing buildings, but the roads are lines, while the buildings were polygons.  Each line segment is created by a click of the mouse ] 

30)       [  Digitizing the lines differs from digitizing polygons in that the beginning and end points are in different locations ]

31) [ 16 , but answers will vary ]

32  [ Answers will vary; could be Road Name, Date Surfaced, Surface Type, Width, Length ] 

33) [ Imagery is a useful resource in a GIS environment, but it must be properly

georeferenced.  ]

[How to locate and download data from the Terraserver Web site into a GIS]

[ Two forms of geographical data available are the DRG and the DOQ ]

[ How to use the World Coordinates file to georeference and image file ]

34)  [ How to create new themes by digitizing over an aerial photograph ]

[ How to add fields and values to an existing attribute table ]   

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