Global Positioning System and GIS

Examining GPS Data (GPS and GIS) Part 3

Manipulating Files {__} Select the three files leading away from the volcano to prepare for combining them into a single file: Under the menu "Utilities" select "Combine." In the resulting "Combine Data Files" window, press "Browse" to bring up a list of files in the folder. Note that as you highlight a file name by […]

Examining GPS Data (GPS and GIS) Part 4

An Aerial Photo That Can Be Used as a Map:The Digital Orthophoto A digital orthophoto image is an aerial photograph, in digital form, with a very useful special property: It has been calibrated so that it may be used as a map; the coordinates of the map are precisely specified. As you may know, most […]

Differential Correction (GPS and GIS) Part 1

IN WHICH we take a closer look at the subject of GPS accuracy and explore techniques that reduce errors. OVERVIEW GPS Accuracy in General When you record a single position with a good GPS receiver, the position recorded will probably be within 5 to 15 meters horizontally of the true location of the antenna. When […]

Differential Correction (GPS and GIS) Part 2

Making Differential Correction Work From a practical point of view, a number of conditions have to be satisfied for the process to work. The base and rover have to be taking data at the same time, and the base has to be taking data frequently. If the base station is to serve the rover, wherever […]

Differential Correction (GPS and GIS) Part 3

PROJECT 4C—McVey Waypoint Waypoints—Using One to Check Your Work {_} The McVey monument is a good candidate for a waypoint since it is a known reference point. We will do this in order to see another way of calculating the distance from a corrected average point to a known point. Still in the __:\GPS2GIS\McVey_NGS directory […]

Differential Correction (GPS and GIS) Part 4

PROJECT 4F—The OK Campus More GPS Files and DOQs In this Project we verify again that differential correction has great value—here we superimpose a GPS trace, on a digital orthophoto, made by walking. {__ } Make a Pathfinder Office project named UK_Campus_yis. Specify its directory to be_:\GPS2GIS\UK_Campus_yis. {_} Use the operating system to copy the […]

AreView, ArcData, and GPS (GPS and GIS) Part 1

IN WHICH you learn to use a part of ESRI’s ArcView software,and use input from the ArcUSA database and GPS files. OVERVIEW What GIS Is The title of this topic, The Global Positioning System and GIS, implies that you can find information here on how to use GPS to develop data for a Geographic Information […]

AreView, ArcData, and GPS (GPS and GIS) Part 2

Starting a New Project…and Saving It {_} Click on the only other Arc View menu item: "File."6 Click on "New Project." A window with the name "Untitled" will appear. See Figure 5—3. {_} Start to save this empty project with a new title: From the "File" menu (note that the menu has changed, now that […]

AreView, ArcData, and GPS (GPS and GIS) Part 3

Identifying Particular Features of a Particular Theme {_} Make I090317a.shp active. Make Cty2m active—which makes I090317a no longer active. (More than one theme may be made active at a time, but this is a more advanced maneuver. For the moment, know how to make a single theme active, and how to make it visible.) {__ […]

Integrating GPS Data with GIS Data

IN WHICH you learn approaches to converting GPS-software1data files to GIS-software data files,^practice with sample GPS and digitized shape files and coverages, and then under take the process on your own. OVERVIEW Another Datum Lesson: I teach at the University of Kentucky’s Department of Geography, in Lexington. Several years ago I borrowed a GPS receiver […]