Lauren Tuttle

2/5/08

GEOG 370

8/10

Lab 2

  1. The buttons in the Data Frame Properties Coordinate System window are clear, transformations, modify, import and new. The clear and transformation buttons remove a current coordinate system and changes one coordinate system to another, respectively. The modify, import and new buttons allow you to edit a coordinate system’s properties, select a new data source and to create a new data source, respectively. Also listed are the add to favorites and remove from favorites, which add and remove selected coordinate systems from a favorites folder.
  1. Under the USA Contiguous Albers Equal Area Conic projection, the United States appears as if it was lying on a spherical globe. The shape of the United States has changed. For example, the northern border of the United Statesis now curved instead of straight. Also, the size of the United States has changed. In the North American Datum of 1983, the size of Alaska and the rest of the United Statesare much larger than in the Equal Area Conic projection. Also, under the North American Datum of 1983, the size of Alaska is very large compared to the United States. Alaska is almost the same size as the United States whereas in the USA Contiguous Albers Equal Area Conic projection, the size of Alaska appears as typically seen on a map or globe. -.5

from planner to conic; GCS preserved the shape; Albers preserves the area

  1. The names and values, respectively, for the coordinate system of the USA Contiguous Albers Equal Area Conic projection are Projection: Albers, False_Easting: 0.000000, False_Northing: 0.000000, Central_Meridian: -96.000000, Standard_Parallel_1: 29.500000, Standard_Parallel_2: 45.500000, Latitude_Of_Origin: 37.500000, Linear Unit: Meter, GCS_North_American_1983 and Datum: D_North_American_1983.
  1. Given the appearance of the data, the Albers Equal Area Projection is not appropriate for viewing the entire world. By solely looking at North America, the projection seems to maintain the appropriate size and shape of the North American countries. However, as you look at the areas closer to the North and South poles, the shape of the countries are distorted.

It is true to area, but it distorts shape and direction.

Can be used to view one country at a time -1

  1. The current view of the ArcMap window is under the layout view. Under this view, several areas on a map can be viewed at once. Each area is called a data frame. The view is comparable to a “print preview” screen. On the right hand side, layers can be turned on and off for each individual data frame.

  1. The three projected data frames are the Mercator, Sinusoidal and Robinson. The Mercator projection appears to preserve shape and area. However, the Earth does not appear as if it lying on a spherical surface. The Sinusoidal projection appears as if the Earth is lying on a rhombus shape. The shape and size of the countries in the middle of the rhombus appears to be maintained. However, the closer to the edges of the rhombus a country is, the more distorted its’ shape and size is. The Robinson projection appears as if the Earth is lying on an oval shape. The shape and size of the countries along the center horizontally across the projection appear to be preserved. However, the top and bottom countries are distorted. The one unprojected Data Frame is the GCS North American Datum 1983. Under this view, the Earth appears if it is lying on a rectangle. The top and bottom countries appear to be stretched.

-.5

The Mercator map increasingly distorts the size of countries as it moves away from the equator. However, it preserves shape. The Robinson projection is only distorts area at the poles. It compromises between area and shape, but is not true to either. The sinusoidal map is an equal area map around the equator but greatly distorts the area as one gets closer to the poles.

Robinson: not a conformal or equivalent projection; average between two or more similar projections which causes the amplitude of distortion across the map not to fluctuate as much as with other projections.

Sinusoidal: presents an accurate representation of area/distance at every parallel and the central meridian

GCS: simply stretched across the screen from right to left

  1. For final map, please see Lab2.jpg within ltuttle student folder.