Title: Data Via The American River Bike Trail

A Case in Point

Author: Clemens F. Arrasmith

Geography 26, GIS Data Acquisition, Spring 1999

American River College

Sacramento, California

Abstract: The following is an exercise in point data creation, manipulation and measurement.

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4. Methodology: The following is the procedural sequence of standards and processes used.

A. Survey Area Criteria:

1. Survey Locale, Conditions and Characteristics:

1. Survey Locale: American River Bike Trail, Sacramento, California.

Location: Between Old Sacramento and Lake Folsom.

Distance: Approximately 32 miles in length.

Direction: East-West, with 4 river crossings.

Elevation: Range East to West 100 to 10 meters.

2. Field Conditions: Early April 1999.

c. Field Characteristics: Trail Conditions.

B. Survey Data Criteria:

1. Trail Mark and Track Positional Accuracy, Survey Instrument Accuracy and Map Positional Accuracy:

1. Waypoint and Trackpoint: Trail Mark and Track Positional Accuracy.

Waypoint Mark: Positional Accuracy within 0.5meter @ 100%

Trackpoint Track: Positional Accuracy within 2.0meters @ 100%

2. GPS Receiver: Garmin, Personal Navigator, XL12:

XL12 Receiver Positional Accuracy within 100meters @ 95%

DCGPS within 1 to 5 meters @ 95%

3DGPS within 15 meters @ 95% undegraded

2DGPS within 100 meter @ 95% degraded

Data Waypoints: 500 max., FOM, set point for each mark.

Data Trackpoints: 1024 max., Wrap, Fill, and Time set intervals.

3. Reference and Base Map Line Accuracy:

1. Survey Data Collections:

1. Trail Marks and Track Positions to Garmin XL12, download to Waypoints Plus:

b. Second Data Set Collection: 9 to 32 mile loop Date 04/11/99

1. Data Set Corrections:

1. Data Set Concatenations: Complete 0 to 32 mile loop

1. Data Set Analysis:

1. Waypoints Plus and Excel, to ArcView, and to ArcInfo:

1. Inspections and Manipulations:

Waypoints Plus, Plots and Tables

Excel and Note Pad, Tables

ArcView, Shapefiles

ArcInfo, Coverages

2. Reference Map Base Line and Data Overlays:

24k USGS Digital Raster Graphics, Quad Files;

Folsom, Citrus Heights, Carmichael,

West & East Sacramento.

Waypoints, File wpall

Trackpoints, File tpall

3. Reference Map Base Line Buffer Zone Data Analysis:

Buffer Zone @ 100 meters about Trail Center Line

Buffer Zone @ 75 meters about Trail Center Line

Buffer Zone @ 50 meters about Trail Center Line

4. 95% Test, Percentage of Data Points within each Buffer Zone:

V. Results: The accuracy of reported points compared against the expected points:

1. Percentage Calculations for the Buffer Zone Points:

1. Total number of points reported within the buffer zone, divided by the total number of points, converted to a percentage.

1. Comparison of Buffer Zone Reported Percentages to Expected Buffer Zone Percentages:

1. Reported Percentages Compared to Expected Percentages:

First Comparison at 95% Expected

Second Comparison at 95% Expected

Third Comparison at 95% Expected

VI. Conclusions: Accuracy of Data Reported to the Data Expected:

A. Accuracy Data Range greater than or less than the expected 95%:

1. Accuracy Less than the 95% Expected

Reported Percentage >= 95% Expected

2. Accuracy Greater than the 95% Expected

Reported Percentage <= 95% Expected

3. Calculated Reported Data Differential Percentage of Error

VII. References:

Management, Bureau of Land Management, Technical Note 389"

Garmin Corporation, 1998. GPS12XL "Personal Navigator Owner’s Manual and

Reference."

Garmin Corporation, 1999. "Global Positioning Systems, Never Get Lost Again."

International AutoSport

Forest Service Project Editorial Staff, 1995. The United States Department of

Agriculture, General Technical Report WO-62, " A Primer on Evaluation and use of

Natural Resource Information for Corporate Data Bases."

Trimble Navigation Limited, 1994. "GPS Mapping Systems General Reference",

Part Number: 24177-00, Revision: A, March.

8. Contact Information: