Creating Spatial Feature Classes Based on Proximity, Overlay, and Attributes - Introducing Geographic Information Systems with ArcGIS - page 415

The lines of TicTacToe are not part of the feature class TicTacToe_BUF, which is strictly a
polygon feature class.

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The buffering process created polygons with a BufferDist of 5, indicating that the area of
that polygon is within 5 meters of the lines that were buffered. The BufferDist field is the
mechanism that allows you to distinguish areas of the spatial field that are within the
buffer distance.

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6. Repeat the buffering process, but this time dissolve the barriers between the features, calling
the output feature class TicTacToe_BUF2. When it appears turn off TicTacToe_BUF. Open the
TicTacToe_BUF2 polygon attribute table. How many polygons are there in TicTacToe_BUF2?
_____. What is the area? _________. You might expect the area to be more than 12,000 square
meters (four 300 meter lines times 10 meters wide) plus the rounded ends. Instead it is less.
Why? _________________________________.

Exercise 7-2 (Project)

Exploring FEATURE CLASS Buffers with the Wildcat
Boat Data

1. In ArcCatalog, make or confirm a folder connection with

___IGIS-Arc _YourInitials \Wildcat_Boat_Data

Close ArcCatalog.

2. In ArcMap with a new Blank map (don't save changes), use Add Data to display the Personal
Geodatabase Feature Classes that depict Sewers and Roads, which you will find in the tree of:

___IGIS-Arc_ YourInitials \Wildcat_Boat_Data

You may bring both feature classes in with a single step by selecting both entry names (click
with Ctrl) and pressing Add. Also add the Soils geodatabase feature class. Zoom to the full
extent of the map.

3. A review: Rearrange the order of the entries in the Table of Contents so that both the layer
Roads and the layer Sewers are below the layer Soils. (Drag each entry by its name.) What does
this say about the order in which layers are drawn? ______________________________. Note
the effect of drawing a polygon layer after line layers. Experiment with turning layers off and
on. Click the List By Source tab at the top of the T/C. Note that you cannot now rearrange the
order. Click the List By Drawing Order tab again. Then rearrange the layers so that the Sewers
entry is at the top and the Soils entry is at the bottom.

4. Open the attribute table for sewers. How many segments of sewer pipe are there? ________.
What are their diameters? ________, ________. Close the table.