Maps tell a story. What does this one tell you?

Symbolization and Classification

GEOG 206: Introduction to GIS

Fall 2010

I. Complete Ormsby Chapters 5 & 6 and answer the following questions.

1. In your own words, describe how symbology can be influenced by scale.

ü  Typically if you where to take a look at an area in a map with a different scale, the symbology is going to be different because if you where looking at the city of LA on a large scale map it would provide you with a lot more detail of the area and the feature would most likely show a polygon. In looking at it from a small scale map, it is covering a greater area so the symbology will be different. An example will be as a dot.

2. What are two ways (one direct and one indirect) to access a layers symbol colors so that they can be changed?

ü  Click the countries layer ->properties-> symbology tab.

ü  Double click the layer you want to symbolize to open the layer property box-> symbology tab.

3. How would you access the graduated symbols classification option?

ü  Double Click layer > layer property dialog box > symbology tab > in the show box click quantities > highlight graduated symbols.

4. What are 5 other symbology styles (in addition to ‘Conservation’) that are available to customize your features?

ü  Transportation, Hazmat, Environmental, forestry, crime analysis.

5. How could you permanently save layer symbology for use later on?

ü  The layer symology needs to be saved as a layer file. Layer files must always be sent with its shapefile for reference.

6. How can pyramids help raster data display faster?

ü   Pyramids help display your raster data faster because they provide the most appropriate level of detail. Finer resolutions are used as you zoom in.

7. How could you quickly and temporarily change a layer name to aid display in the Table of Contents?

ü  Just double click on the layer name and layer property will open up > got to the general tab > Layer name.

ü  A faster way to do it is to just right click on the layer once and wait for it to highlight .  

8. What is normalization? Dividing one attribute by anther to find the ration between them is called normalization.

 Give an example of when it would be used.

ü  Normalizing population by income. 

ü  Normalizing population by area.

9. How could dot density maps be misleading?

ü  Dot density maps reveal meaningful overall patters, but the random distribution of dots can be misleading if you focus on small areas. GIS will randomly place for example five dots randomly within the given area you tell it to. Inside such area the dots are placed randomly.