Mastering GIS Chapter 1

Question 1

more resolution vs less resolution

Answer 1

HIGH RESOLUTION
-smaller map area, blocky, less space
LESS RESOLUTION
-bigger map area, less blocky, more space

Question 2

Large scale vs small scale

Answer 2

LARGE SCALE
-ratio is large (small denominator), small areas [1: 24 000]
SMALL SCALE
-ratio is small (large denominator), bigger areas, [1: 100 000]

Question 3

What is a source scale

Answer 3

-original scale/resolution that was converted digitally. Have to pay attention to source scale because you lose detail when zooming into a large scale.

Question 4

what is data quality? how do we evaluate the quality of data?

Answer 4

-degree of generalization
EVALUATE BY:
geometric accuracy
thematic accuracy
resolution
precision
metadata (info about a dataset, source of info, development, who collected the data, precision)

Question 5

What are shapefiles?

Answer 5

are spaghetti data models that consist of a feature class composed of points, lines, polygons but never a mixture. they have multiple data files
TYPES
dBase: stores attributes
multipart features: single feature has multiple objects
shp: stores coord data
dbf: stores attribute data
shx: stores spatial index that speeds drawing and analysis
(need each one for a shapefile to work)

Question 6

Tell me about a geodatabase

Answer 6

contain feature classes, networks, tables, rasters, topology

• can exist as individual objects in a geodatabase or can be grouped into freature system
• can store rasters

Question 7

What types of geodatabases exist?

Answer 7

Personal
File
SDE: store GIS data within commercial relational database management system (RDBMS) (ie Oracle or SQLServer). Designed for security and management needs for large datasets that are looked at by many users simultaneously

Question 8

What are coverages?

Answer 8

• is an old vector format
• has to be converted to a shapefile or exported to a geodatabase
• has multiple feature classes
• stores topology

Question 9

What formats can rasters be stored in?

Answer 9

JPEG, TIF, GEOTIF, BMP, MrSID, BIP, BIL, BSQ

Question 10

what types of GIS servers exist?

Answer 10

• map service (map layers as tiles and sends them to the user as static images. Fast, efficient, however cannot be modified.)
• feature service (: shares the requested data features. Slower, can change how the features look and edit/analyze them)
• layer package (sends to client for local use)
• image service (see large imagery)
• geoprocessing service (makes available certain computations and functions so analysis can be preformed through a web site.)