502 Spatial Data Generalization Methods

Question 1

Aggregation definition

Answer 1

combining features into a larger feature (summarizes)

Question 2

Why would you want to aggregate?

Answer 2

Show patterns
Reduce detail

Question 3

Smoothing definition

Answer 3

Simplify shape of features by removing small irregularities

Question 4

Douglas-peucker algorithm smoothing

Answer 4

simplifies lines by keeping essential vertices

Question 5

Bezier curves smoothing

Answer 5

smooths curves by approximating them with control points

Question 6

Simplification of lines

Answer 6

Reducing number of vertices

Question 7

Line generalization algorithms (simplification)

Answer 7

Simplify complex shapes

Question 8

Why would you want to simplify your geometry?

Answer 8

Renders faster and reduces storage

Question 9

Resolution reduction

Answer 9

decrease the spatial resolution of raster data

Question 10

Resampling (resolution reduction)

Answer 10

Average the pixel values within larger cells (increase cell size and average within the new cell size)

Question 11

Pyramid layers

Answer 11

Creates lower-resolution versions of data (faster rendering)

Question 12

Hierarchy creation (what does it do?)

Answer 12

Organizes features into levels

Question 13

Hierarchy creation example

Answer 13

Grouping roads into primary/secondary/local

Question 14

Edge matching definition

Answer 14

Making sure topology between map sheets/tiles is seamless

Question 15

Does raster or vector data tend to be more precise about its location?

Answer 15

Vector

Question 16

Topological simplification

Answer 16

Getting rid of topological details but still keeping important ones

Question 17

How do shapefiles store attribute and geometric data?

Answer 17

Attribute = dbf file
Geometry = shp file

Question 18

How do GeoJSON files store geometric and attribute information?

Answer 18

Together (object-based)

Question 19

Indexing

Answer 19

Access structure in a database so you can get a specific record easier

Question 20

Can geographic features be represented on a map without undergoing transformation?

Answer 20

No

Question 21

Elimination (simplification)

Answer 21

removing features from a map

Question 22

Tessellation (simplificaiton)

Answer 22

Approximate coordinate grids by making a continuous surface into cells

Question 23

2 types of tessellation

Answer 23

triangulated irregular network
raster

Question 24

What are the 3 components of a TIN tessellation?

Answer 24

points of the triangle have x/y coordinates, elevation, and slope

Question 25

Collapsing (transformation method)

Answer 25

Like a polygon river down to a single line to simplify