Lecture 01/01/2017

Question 1

How are Raster data are represented in space?

Answer 1

By an array (or grid) of cells (pixels) which contains a value that describes the phenomena being examined.

Question 2

What kind of meta data is raster data best positioned to display?

Answer 2

Raster data models are mainly used to describe and depict spatial entities (temperature, precipitation, elevation, etc.) that are continuous across a landscape (e.g., DEMs)

Question 3

What are the two metrics used to store data in Raster File Formats?

Answer 3

1. Cell Size - x,y dimension of a pixel

2. Cell Value - coded representation

Question 4

How is Raster data georeferenced to relate them with other spatial datasets?

Answer 4

By control points (e.g., upper left corner coordinate, lower right corner coordinate). Georeferenced values can also be interpolated within individual pixels as representing specific coordinates.

Question 5

What are the different Raster Data Structures?

Answer 5

1. Simple rasters
2. Run-length encoding/Block coding
3. Chain coding
4. Quadtrees

Question 6

What happens when you convert from vector to raster and raster to vector?

Answer 6

Vector to raster: diagonal lines look like staircases if the resolution isn’t high enough.

Raster to vector: you get splinters and triangles.