Creating a Flat Earth Image

Question 1

What is the difference between graticule and grid

Answer 1

Graticule Latitude and longitude is an example. For grid X/Y coordinates is an example.

Question 2

Transverse

Answer 2

Rotated cyclindar 90 degrees

Question 3

Developable Surface:

Answer 3

A geometric shape such as a cone, or cylinder, that can be flattened without being distorted. Many map projections are classified in terms of these shapes.

Question 4

Cylindrical Projection

Answer 4

Cylindrical projections result from projecting a spherical surface onto a cylinder. Can be tangent or secant. A secant cylindrical projection has 2 lines of intersection between the cylinder and the globe both are small circles. When the cylinder is tangent to the sphere contact is along a great circle (the circle formed on the surface of the earth by a plane passing through the center of the earth. Cylinder is a good projection for wanting all of earth! The end result is a rectangular map!

Question 5

Conic Projection

Answer 5

Conic projections result from projecting a spherical surface onto a cone. When the cone is tangent to the sphere, contact is along a small circle. In the secant case the cone touches the sphere along 2 lines, one great circle and the other a small circle. Not a good projection if wanting to map all of earth. Great for one of the poles.

Question 6

Planar Projection:

Answer 6

Results from projecting a spherical surface onto a plane. When the plane is tangent to the sphere contact is at a single point on the surface of the earth. In the secant case the plane touches the sphere along a small circle if the plane does not pass through the center of the earth when it will touch along a great circle.

Question 7

Line of Tangency

Answer 7

When a developed surface comes into contact with the globes surface along a single line the projection is considered to be tangent. (the projection surface is tangent to the globes along that line).

Question 8

Line of Secancy

Answer 8

When a developed surface comes into contact with the globes surface along 2 lines, the projection is considered to be secant! ( the surface cuts through the surface of the globe)

Question 9

Secant Cylindrical Projection:

Answer 9

the cylinder touches the sphere along 2 lines, both small circle (a circle formed on the sruface of the earth by a plane not passing through the center of the earth)

Question 10

Tangent Cylindrical Projection:

Answer 10

Contact is along a great circle (the circle formed on the surface of the earth by a plane passing through the center of the earth)

Question 11

What happens when the cylinder upon which the sphere is projected is at a right angle to the poles?

Answer 11

The cylinder and resulting projection is transverse! When the cylinder is at some other non-orthgonal angle with respect to the poles the cylinder and resulting projection is oblique.

Question 12

When the cone is tangent to the sphere, contact is along what?

Answer 12

A small circle!

Question 13

When the cone is secant to the sphere the cones touches the sphere along….

Answer 13

2 lines! one a great circle and the other a small circle.

Question 14

In a planar projection what happens when the plane is tangent to the sphere?

Answer 14

The contact is at a single point on the surface of the earth.

Question 15

In a planar projection what happens when the plane is secant to the sphere?

Answer 15

The plane touches the sphere along a small circle if the plane does not pass through the center of the earth, when it will touch along a great circle.

Question 16

What are the different types of light sources?

Answer 16

1. ) Orthographic: Infinite light source. A view of the world from a vetical perspective. As if you were looking at it at the entire earth from directly above the surface.
2. ) Stereographic: Light source at antipode
3. ) Gnomic: Light source at center of globe. Map projection with a theoretical

Question 17

Equation for Scale Factor

Answer 17

Actual scale/Principal Scale= Scale Factor

Question 18

Scale factor is used for

Answer 18

Understanding the amount of distortion on the map

Question 19

Lambert Azimuthal Equal Area is a product of….

Answer 19

Planar surface

Question 20

mercator projection is also a

Answer 20

cylindrical projection

Question 21

If we move away from a standard line does distortion increase or decrease?

Answer 21

It increases!

Question 22

What does a conformal map preserve?

Answer 22

Shape preservation

Question 23

What does a Equidistant Map Preserve?

Answer 23

Distance

Question 24

What does a Azimuthal Map Preserve?

Answer 24

Direction

Question 25

What does an Equal Area Map Preserve?

Answer 25

Area

Question 26

Can a map projection maintain scale everywhere?

Answer 26

NOPE

Question 27

What does a Mercator Projection Preserve?

Answer 27

It is a conformal map so it maintains shape!

Question 28

Lambert Conformal Conic projection, what does it preserve and distort?

Answer 28

Area and Shape are distorted away from standard parallels. Directions are true in limited areas.

Question 29

What is the official projection of Canada?

Answer 29

Lambert Conformal Conic

Question 30

Azimuthal equidistant projection what does it preserve and distort?

Answer 30

• Distances measured from the centre is true.
• Distortions of other properties increases as you move away from the center point!
• Sometimes used to show air-route directions.

Question 31

In order to preserve area what happens as we get fartheraway from the standard line?

Answer 31

compresses

Question 32

Where is the only place you can preserve shape and area?

Answer 32

The standard line, the standard point or standard lines!

Question 33

Secant Planar has a

Answer 33

single standard line.

Question 34

Tissot’s Indatrix:

Answer 34

Equal area map. Represents circles of distortions with the intersection of long and lat. We apply to those circle the distortion that that area is experiencing.

Question 35

Why would we want to use the mercator projection?

Answer 35

If mapping the equator! Because the equator is the standard line where there is no distortion.

Question 36

What geographic considerations might contribute to projection selection?

Answer 36

• Shape of area
• Extent of area
• Critical features
• Region or area of the earth.

Question 37

Principal Scale:

Answer 37

(scale of a globe radius to atual earth radiues). scale of the model of earth being used for a map to the earth. Principal scale and actual scale will be the same all over the reference globe.

Question 38

Actual scale:

Answer 38

The scale at any point on a maps surfacr in relation to the earth.