Datum - ANSWER: Provides a frame of reference for discovering locations.
Based on a spheroid.
Minor Axis - The shorter axis of the ellipse.
- North-to-South
The Earth's shape is an oblate ellipsoid because it revolves on its minor axis.
Prolate Ellipsoid - If the Earth revolved along its primary (longer; West/East)
axis
Ellipsoid is a model of the earth's spherical shape, which bulges at the equator.
ANSWER: Ellipsoids are measured using semi-axes.
- Semimajor and semiminor axes.
Spheroid - an ellipsoid that resembles a sphere.
- More descriptive, as used by Esri
- Spheroid projections: WGS84 and WGS72
The two definitions of a spheroid - ANSWER 1. An ellipsoid that approximates
the shape of a sphere (used in this course).
,2. An ellipsoid formed by rotating an ellipse around its major axis (prolate
ellipsoid) or minor axis (oblate ellipsoid)
The most prevalent spheroid projection in North America is currently GRS80,
which is replacing the former.
Formerly: Clark 1866.
Authalic Sphere - ANSWER A sphere with the same surface area as the
spheroid (to simplify calculations).
Choosing a spheroid model - ANSWER - Less than 1:5,000,000: Can use an
authalic sphere
- For values greater than 1:5,000,000, a spheroid may be required.
How to discover information (such as the map projection): ANSWER Right-
click layer, properties, source.
How do you access the swiping function? - ANSWER: 1) Click the layer.
2) On the ribbon (top area with tabs), select the feature layer contextual tab.
3) Select "Swipe" from the "Compare" option.
How do you measure with ArcGIS Pro? - ANSWER: 1) Open the ribbon map
tab.
2) Click "Measure" in the "Inquiry" section.
, Who established the system of what we now call latitude and longitude? -
Answer: Hipparchus
What's another name for latitude and longitude? - ANSWER Parallels and
Meridians (based on 360°)
What is the equivalent of 360 degrees in terms of latitude and longitude? -
ANSWER: Each degree is divided into 60 minutes.
- Each minute is divided by 60 seconds.
Lines of Latitude - Answer: Parallel
- Run east and west.
- Measure distances from north or south of the Equator.
- THE SIDEWAY LINES
ANSWER: Lines of longitude run north and south.
- intersect at the poles.
- Measure distances east and west of the Prime Meridian.
- The lines go up and down.
The Graticule is a network of crossing lines of latitude and longitude.
Lines of latitude - A circle that splits the world into two equal half - the
Equator.
Based on a spheroid.
Minor Axis - The shorter axis of the ellipse.
- North-to-South
The Earth's shape is an oblate ellipsoid because it revolves on its minor axis.
Prolate Ellipsoid - If the Earth revolved along its primary (longer; West/East)
axis
Ellipsoid is a model of the earth's spherical shape, which bulges at the equator.
ANSWER: Ellipsoids are measured using semi-axes.
- Semimajor and semiminor axes.
Spheroid - an ellipsoid that resembles a sphere.
- More descriptive, as used by Esri
- Spheroid projections: WGS84 and WGS72
The two definitions of a spheroid - ANSWER 1. An ellipsoid that approximates
the shape of a sphere (used in this course).
,2. An ellipsoid formed by rotating an ellipse around its major axis (prolate
ellipsoid) or minor axis (oblate ellipsoid)
The most prevalent spheroid projection in North America is currently GRS80,
which is replacing the former.
Formerly: Clark 1866.
Authalic Sphere - ANSWER A sphere with the same surface area as the
spheroid (to simplify calculations).
Choosing a spheroid model - ANSWER - Less than 1:5,000,000: Can use an
authalic sphere
- For values greater than 1:5,000,000, a spheroid may be required.
How to discover information (such as the map projection): ANSWER Right-
click layer, properties, source.
How do you access the swiping function? - ANSWER: 1) Click the layer.
2) On the ribbon (top area with tabs), select the feature layer contextual tab.
3) Select "Swipe" from the "Compare" option.
How do you measure with ArcGIS Pro? - ANSWER: 1) Open the ribbon map
tab.
2) Click "Measure" in the "Inquiry" section.
, Who established the system of what we now call latitude and longitude? -
Answer: Hipparchus
What's another name for latitude and longitude? - ANSWER Parallels and
Meridians (based on 360°)
What is the equivalent of 360 degrees in terms of latitude and longitude? -
ANSWER: Each degree is divided into 60 minutes.
- Each minute is divided by 60 seconds.
Lines of Latitude - Answer: Parallel
- Run east and west.
- Measure distances from north or south of the Equator.
- THE SIDEWAY LINES
ANSWER: Lines of longitude run north and south.
- intersect at the poles.
- Measure distances east and west of the Prime Meridian.
- The lines go up and down.
The Graticule is a network of crossing lines of latitude and longitude.
Lines of latitude - A circle that splits the world into two equal half - the
Equator.
