Lecture 25/01/2017

Question 1

What you need to think about when selecting or using Projections and Datums?

Answer 1

1. Are my datasets in the same projection?
   –If not, what can happen?
2. Are my datasets in the same datum?
   –If not, what can happen?
3. Do my datasets have a projection, datum or coordinate system?
   –How do I check this?
4. What properties am I trying to retain?
   –Conformity, Distance, Area, Direction?

Question 2

By selecting the right datum, what are you hoping to avoid?

Answer 2

Positional errors

Question 3

What can happen if two layers are not in the same datum?

Answer 3

Positional errors

Question 4

What is the difference b/w geographic coordinate systems and projected geographic coordinate systems?

Answer 4

WGS1984 vs. NAD1983

Question 5

What tool do you use in ArcMap to set a projection for a particular layer?

Answer 5

“define projection”

Question 6

What tool do you use in ArcMap to convert from one projection to another?

Answer 6

Project transform.