Symbology
Layer Properties give the user the ability to display information in a logical format and make changes. One of the most used tabs in layer properties is symbology, it provides the ability to control data and the properties of it’s appearance. In the symbology tab the user has the ability to control items such as color, line width, line type, fill colors, as well as different types of classifications of the data. In the earlier discussion of shapefiles the symbology tab was used to change the default representation, as seen in Figures 20 – 23. For the point data the symbol was changed from a default to a hospital symbol to better represent the information. On the line image the colors of the rivers and county boundaries were changed to different colors to better describe the information. For the polygon data, the appropriate attribute were chosen as well as the ramp colors and break points for different colors to display.
Labeling Maps
The labeling tab gives the user the ability to label features which makes it easier to understand what the map represents. Care must be taken not to place an excessive amount of information onto the map. This would obscure features on the map making it hard to understand. For example, if a state map is being viewed on a standard size page, the designer should not label every city street in every city in the state. In the same fashion when the user is at the street level of an individual city this might be appropriate. Utilizing a dynamic zoom that automatically turns on and off labels at different zoom levels makes for more versitile maps. A similar functionality can be used for layers.
Query
A query is a request of the data for specific information to be displayed, instead of showing all the information. Such as writing a statement to show income levels over a certain threshold. The definition query tab gives the designer the ability to select specific features based upon a logical criteria. Functionality logic terms such as greater than, greater than or equal, less than, less than or equal, equal will be used as well as logic functions such as AND and OR.
Additional Map Features
All properly created maps should contain additional information about the features that help the user understand what the map is displaying. While additional documentation of a map is required to fully understand the analysis of data and conclusions drawn from data, it is important that a map conveys information directly by observation only. Maps should have a title box giving a descriptive name. A text box that provides information about the maps creator, the firm which created the map, contact information and when the map was produced. A north (directional) arrow and scale indicator are important for an understanding of the location and alignment of the map. A legend is required to explain the symbols and the colors used in the map creation. Additional text boxes can be added to explain the map, especially if it is going to be created in a large format. These features are needed for both static maps, as well as dynamic representations. Static maps can be created as both electronic or paper copies, dynamics maps will always be electronic.
Remote Sensing
Remote Sensing is the ability to gather data without direct contact. For example, a satellite in orbit around the earth has cameras taking images of the earth’s surface. The image data received by the camera is transmitted by the satellite to a ground receiving station. The image received is georeferenced so that the image data can be used for spatial analysis. Another example might be an Unmanned Aerial Vehicle (UAS, Drone) flying a corn field. The images are taken by an onboard camera and downloaded to a computer workstation. The images are separated by color bands and specific patterns (signatures) which are analized to identify different surfaces. Those areas identified might be in the need of weed control.
Passive remote sensing is the gathering of information by reflected or emitted electromagnetic radiation. This information might be in the infrared, visible and ultraviolet regions of the spectrum. Normally information of this type is detected by either an airplane or satellite. Active remote sensing is when a device emits electromagnetic energy, it strikes the surface of the earth and the reflected energy is recorded by a sensing platform, such as radar to measure the elevation of the earth’s surface.
The study of remote sensing is introduced in this course, additional information about remote sensing can be obtained by taking a complete introductory course.
Passive remote sensing is the gathering of information by reflected or emitted electromagnetic radiation. This information might be in the infrared, visible and ultraviolet regions of the spectrum. Normally information of this type is detected by either an airplane or satellite. Active remote sensing is when a device emits electromagnetic energy, it strikes the surface of the earth and the reflected energy is recorded by a sensing platform, such as radar to measure the elevation of the earth’s surface.
The study of remote sensing is introduced in this course, additional information about remote sensing can be obtained by taking a complete introductory course.
Report Creation
While creating maps is a very important part of geospatial technology, it is not the sole job of the geospatial specialist. The specialist must also provide a written assessment of what was discovered through the research process. Maps need to be integrated (embedded) into reports as well as graphs and data tables. This information provides the foundation for the creation of the analysis of the information. Basic word processing, spreadsheet creation and database usage are required skills for a successful analysis. Microsoft Office does a good job for report creation. If you do not have this software package, Google Docs can be used (http://docs.google.com) or Open Office (http://www.openoffice.org) both free packages. Make sure documents are in standard formats such as Microsoft Word, Microsoft PowerPoint or Microsoft Excel. The end of any report should contain appendixes which provide larger diagrams, PowerPoints and required credits. In addition the materials created for clients need to be placed in a format that allows for maximum flexibility of the information, but not allow for the client to alter the conclusions of the geospatial specialist. It is recommended that final reports always be provided in a printable format such as Adobe Acrobat (pdf). There is free software that can be used to create pdfs. CutePdf (http://cutepdf.com/) is a good one.