CP6514_Practice Exercise 4

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Jan 9, 2024

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Maribeth Price, 2020: Mastering ArcGIS Pro – Second Edition. NY: McGraw Hill Practice Exercise #4 1. Examine the coordinate system for the streets feature class in the Austin geodatabase. What is the name of the coordinate system? Is it projected or unprojected? What are the map units? Projection parameters of the feature classes in the Austin geodatabase are as follows: Name of the coordinate system: NAD 1983 StatePlane Texas Central; Whether or not it is projected: Yes (Projected); Map unit: US Feet 2- What is the name of the projection (not the coordinate system) used by the feature classes in the Oregon geodatabase? What are the central meridian and the standard parallel(s)? Does it use the equator for the latitude of origin? Projection parameters of the feature classes in the Oregon geodatabase are as follows: Name of Projection: Lambert Conformal Conic Central meridian: -120.5 Standard parallel (1): 43.0 Standard parallel (2): 45.5 No. Latitude of origin: 41.75 3- Determine the coordinates of the summit of Mount Rainier, Washington, in (a) degrees- minutes-seconds, (b) UTM Zone 10 (in meters), and (c) Washington State Plane South (in US feet). Use the NAD 1983 datum in all cases. The coordinates of the summit of Mount Rainier, Washington, with different coordinate standards are as follows: (a) Degrees-minutes-seconds: 46°51'11"N 121°45'37"W (b) UTM Zone 10: 5,206,425 meters Northing, 562,653 meters Easting (c) Washington State Plane South: 17,101,540 feet Northing, 767,823 feet Easting 4- Compare the projection parameters of the North America Equidistant Conic and the USA Contiguous Equidistant Conic predefined coordinate systems. Explain the reason for the differences. USA Contiguous Equidistant Conic and North America Equidistant Conic share the same central meridian, GCS, and Datum. However, they have different standard parallels and the latitude of origin. It reflects the fact as follows: USA Contiguous Equidistant Conic acknowledges the onshore United State, which excludes Alaska, as a coordinate system boundary, whereas; North America Equidistant Conic includes the North American subcontinent, which includes the United States, Alaska and Canada as a coordinate system boundary. Projected Coordinate System Projection parameters North America Equidistant Conic USA Contiguous Equidistant Conic Central Meridian -96 Standard Parallel 1 20 33 Standard Parallel 2 60 45 Latitude of Origin 40 39 GCS / Datum NAD 1983 / D North American 1983
5- Examine the standard parallels and the latitude of origin of the Africa Lambert Conformal Conic predefined coordinate system and state them. Predict whether any areas of Africa have negative y coordinates in this projection. Why or why not? Africa Lambert Conformal Conic has the following projection parameters: Projected Coordinate System Projection parameters Africa Lambert Conformal Conic Standard Parallel 1 20.0 Standard Parallel 2 -23.0 Latitude of Origin 0.0 GCS WGS 1984 Datum D WGS 1984 Given the above facts, some areas of Africa which locates south to the equator line (latitude of origin) will have negative y coordinate. 6- Is the Africa Lambert Conformal Conic projection a tangent or a secant projection? How can you tell? Africa Lambert Conformal Conic has 2 standard parallels which shows it’s a secant projection. 7- What datum is used for Africa Lambert Conformal Conic coordinate system? Why is it different from the one used for the North America Equidistant Conic coordinate system? Africa Lambert Conformal Conic coordinate system utilizes D WGS 1984 datum, an earth- centered datum , to best represent the approximate shape of the African continent. As the African continent is located close to the equator, it can be best projected by D WGS 1984 which sets its latitude of origin as 0, where the equator line exists. On the other hand, North America Equidistant Conic coordinate system utilizes D North American 1983 datum, a local datum , to best represent the approximate shape of the whole North American continent. The continent is far north to the equator line. Therefore, approximate shape of the continent might be distorted if it uses WGS 1984 datum which sets the equator line as its latitude of origin. 8- Create a new map and add the utmzone.shp data set from the mgisdata\World folder and the spcszn83 feature class from the mgisdata\Usa\usdata geodatabase. Examine these locations relative to the UTM and State Plane zone boundaries. Select which zone would be a better (less distorted) choice for the area, and explain why. (Amarillo, Texas / Pensacola, Florida / State of Tennessee) Three mentioned locations are situated in the following zone boundaries: Zone Located Place UTM State Plane Zone Amarillo, Texas 14S zone Texas North zone Pensacola, Florida 16R zone Florida North zone State of Tennessee 16S and 17S zone Tennessee zone To determine which zone would be a better choice for the area would first start by answering the characteristics of UTM and State Plane projection. State Plane projections are designed to best measure a particular region (in this case USA) with minimum distortion within the particular region. On the other hand, UTM projections are used to measure a small area within a single UTM zone. However, if the area of interest goes beyond the boundary of a UTM zone, distortion might happen when it is projected. Therefore, in this case State Plane zone would be a better choice f or the area.
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