CS 128/ES 228 - Introduction to Geographic Information Systems

Lab 5: Vector Formats

Goals:

        By the conclusion of this lab period, you will have:

  1. Further examined the difference between vectors and rasters.
  2. Learned how to manipulate various vector entities within ArcMap.
  3. Incorporated external, vector-based data into an existing map file.

 Vector vs. Raster, Round 2

  1. Looking at vectors and rasters.  Start ArcMap on one of the lab computers and open our standard data set.  Arrange things so that the local roads layer and the photo covering campus are visible.  Zoom in on the traffic circle near the Quick Arts Center, Rob/Fal and Doyle.  Focus your attention on the center of the circle, i.e. the part on which the cars do not drive.  Answer the questions on Part I of the attached worksheet about this circle. 
    2.  
  2. Manipulating vertices.  Vertices can be manipulated in ArcMap while editing the layer in which they sit.  To move a vertex, select its line (while editing), move the mouse over the vertex (the cursor will change) and then use the mouse to drag the vertex to its new location.  Without adding any vertices, try to reshape the interior circle to better match the photo.  Don't worry about the exterior road boundary.  Answer the questions on Part II of the attached worksheet about this circle.
    3.  
  3. Adding vertices to polylines.  The editor will also permit you to add vertices (or delete them) to a polyline.  To do so, simply select the polyline, move the mouse over an edge, and then right click and choose Insert Vertex.  The vertex will be inserted right on the line, but can then be moved as in the previous step.  Use this technique to better model the interior of the traffic circle.  Now answer Part III of the worksheet.

Area Features

  1. A new layer. Begin by adding a new layer to the map.  This layer is currently called "Bonus".  Download each of the files found here (sbu buildings.dbf,  sbu buildings.shp, sbu buildings.shx and add them to the folder containing the map.  Then add this layer to the map.  Examine the data, give it a more appropriate name, and then proceed to Part IV of the worksheet.


  2. Editing Polygon Features. Using the approach from Steps 2 and 3 and applying the various tools, try to do each of the following: 
    1. adjust the shape of the baseball field,
    2. "round" the track by adding vertices,
    3. "split" the soccer and softball fields, and separate them,
    4. remove any extraneous data from the layer.
    3.  

CAD Drawings

  1. Adding a CAD drawing. In principle, a CAD drawing is added just like any other layer.  In practice, there may be issues of alignment.  Try to add the drawing 4692-2a (available from Dr. Levine if the link is problematic.)  Attempt to get the CAD layer to register with the aerial photo.  What you are going to do is to find two points (in the real world) about whose location you can be sure in both the CAD drwing and the aerial photo.  You will then use the coordinates of the point in each system to define a mathematical transformation between the two images.  Once you know the coordinates of your two points in both systems, you are ready to begin.  Right-click on the CAD layer in the Table of Contents.  Choose Properties, and the Transformations tab.  On this page, choose to Enable Transformations and to Transform by Coordinates.  In the fields, put the CAD coordinates in the From column and the corresponding aerial photo coordinates in the To: column.  Apply the transformation and see if they align.  If not, check the values of your coordinates.

 

 

To Hand In

You are to create a text document including the answers to the questions on the worksheet.  In addition, you are to take a screen snapshot of the map showing all (and only) the layers you modified in the lab.  If necessary, take two snapshots.  Add the snapshots to the write-up, put a cover page on front, and email it to your instructors.

 

Help Policy

       Help Policy in Effect for This Assignment: Group Project With Limited Collaboration

       In particular, you may discuss the assignment and concepts related to the assignment with the following persons, in addition to an instructor in this course: any GIS instructor and any student enrolled in CS 128/ES 228.

       You may use the following materials produced by other students: materials produced by member of your own group.