503 Spatial Data Types - Raster

Question 1

What is a GeoTIFF?

Answer 1

geo-referenced raster image

Question 2

What does a GeoTIFF typically have attached to it?

Answer 2

Embedded metadata

Question 3

What is a JPEG 2000 used for?

Answer 3

Compression of large imagery

Question 4

What is an ArcGIS Grid/ADF file?

Answer 4

proprietary Esri format for raster datasets

Question 5

What does DEM stand for?

Answer 5

Digital elevation model

Question 6

What do the cells in a DEM represent?

Answer 6

Elevation values that exclude anything on top of the bare earth

Question 7

What data do LiDAR files store?

Answer 7

Point cloud data

Question 8

What does each data point in a LiDAR file have in it (4)?

Answer 8

X, Y, Z coordinates
Intensity values
Return numbers
Classification codes

Question 9

What are TINs typically used for (2)?

Answer 9

3D modeling/visualization
Representing terrain surfaces

Question 10

3 advantages of rasters

Answer 10

1. Representing surfaces
2. Easy to draw on a screen
3. Easier analysis

Question 11

4 disadvantages of rasters

Answer 11

1. Often large to store
2. Large cell size = information loss
3. Not good at representing discrete features (points/polygons)
4. Each cell can only represent 1 classification

Question 12

Why is vector to raster conversion difficult?

Answer 12

pixels can distort real world locations of features and could need digitization/transformation because of errors