James R. Carter

The Effect Of Data Precision On The Calculation Of Slope And Aspect Using Gridded Dems

Plots of the frequency of occurrences of aspect angles calculated from gridded DEMs showed inordinately large spikes at the cardinal directions. Because such frequencies are not natural, the techniques of calculating slope and aspect were examined. Ultimately, the cause of the spikes was found to be the fact that the elevation values are reported only to the nearest meter. Calculations of slope and aspect angles using rounded elevation data from simulated surfaces of known slope and aspect demonstrate the nature of the problem. These simulations show that the problem of defining aspects is greatest on the most gentle slopes, as well as smaller grid spacings. Consideration was also given to various techniques of selecting elevations for deriving the parameters in the slope and aspect equations. At lower slopes, calculated aspects may be off by tens of degrees. Because there is no way to make the data more precise, researchers should exercise caution in making interpretations of aspect angles. Calculations ...

The Map Viewing Environment: A Significant Factor in Cartographic Design

The effectiveness of the map viewing experience is a function of the map viewing environment, the knowledge and motivation of the viewer, and the design and presentation of the graphic image. The paper map to be read by the viewer in full control of the viewing environment is the traditional focus of the cartographer. Because maps are now seen in a diversity of environments on a wide range of media, cartographers and presenters of maps need to give more attention to the map viewing environment. The viewing environment is important in terms of the viewers control of the situation, the time available to view the graphic, the legibility of the graphic image, the expectations of the viewer and the ability to sequence a presentation. The way the map is presented to the viewer has a direct impact on the effectiveness of the map reading experience. A series of questions is offered to alert the designer and/or presenter to the constraints that will be imposed on the map viewer in any given environment.

Dora the Explorer: Preschool Geographic Educator

Abstract Dora the Explorer is a twenty-three-minute television program for preschoolers viewed by millions every day in many countries. These programs are also marketed as videotapes and DVDs. This seven-year-old Latina, bilingual cartoon character teaches many things by interacting with the young viewers. On every program Dora and friends have to go someplace to solve a problem. Map is a cartoon character who helps viewers read the map and tells Dora where to go next. Some episodes are particularly geographic. Geographers need to evaluate the contributions of Dora the Explorer to geographic education for preschool children, a little-studied subject.

Uses, Users, and Use Environments of Television Maps

Weather maps have been part of our television environment for more than half a century and, as such, have become part of our culture. Weather maps are seen in a unique environment where users know when and where to tune in to see maps that they have become comfortable viewing. It is argued that these weather maps are good examples of animated cartography and complementarity in cartography. Weather programming on U.S. television is grouped into four types: local, national, all-news, and all-weather. Although it can be argued that more people see weather maps on television than any other type of map, these weather presentations are designed and produced by a community which includes few if any cartographers. The weather maps are used in many different ways, including a general education of the public and entertainment comparable to watching a sporting event. A typology of weather map users is developed based on what users want to get from the maps.

Unusual Ice Formations: Studying the Natural Growths of Ice from Soils, Stems, Branches, and Rocks

n the August 1980 issue of Weatherwise a reader asked about a photo “showing plant-like shoots of ice that grew up from the soil in thin, parallel fragile bundles.” Dr. Charles Knight of the National Center for Atmospheric Research (NCAR) responded that this “is usually called ‘needle ice’” and gave a brief explanation for how it is thought to occur. The existence of this and similar forms of growing ice has been documented in articles and letters dating from the 1820s, but with digital cameras, the Internet, and search engines, many people are now able to share their findings with the world. As a result, a number of attractive formations of ice growing from different media have recently gained public exposure. The most commonly observed types of such ice are needle ice, ribbons of ice, hair ice, and ice on rocks. I believe this article represents the first time that these four types of growing ice have been discussed in one publication. Unusual Ice Formations

The application of the intercolor 8000 terminal to thematic cartography

The Intercolor 8000 color video terminal is used in conjunction with a timesharing computer system for applications in thematic cartography. The version of the terminal discussed can resolve the screen into a matrix of 25 rows by 80 columns with colored characters on colored backgrounds. Using the plot mode, the screen can be further resolved into single-color cells of 100 rows by 160 columns. The value and limitations of the terminal are discussed in terms of the selection and brightness of the eight colors, the dimensions of the cells and the ability to mix colors in small cells. The possibilities of using the terminal for dot, choropleth and isarithmic maps are explored. Acetate overlays can be used to add base lines such as boundaries and rivers and the composite images can be recorded on standard slide film.

The added dimension of geographic data

Geographic base files and data bases are unique from other digital data because they must be related to specific places on the earths surface. Such digital files carry implicit or explicit indicators telling where features exist or events occur. Geographic phenomena may be identified with a point, along a line or within an area. An area may be defined as an irregular polygon, such as a county or a state, or by a regular cell in a matrix. A well, a house or the site of an accident would normally be defined as occurring at a point. Streets, rivers and contours are generally represented as lines. Counties, watersheds and service areas are described by irregular polygons that outline areas. Such logic may be extended to apply to three dimensional situations such as a volume of air space in an air quality study or the mass of overburden to be removed in a mining operation.

What Should Be Included in a Cartography Program? Report on a Discussion by Geographer-Cartographers

A roundtable discussion among geographic cartographers considered what should go into a cartography program within a geography department to serve various ends. Five specific aspects of cartography were addressed formally—history of cartography, map design, analysis of cartographic data, map perception and psychophysics, and computer cartography. The ensuing discussion focused mostly on what training should be offered to prepare the student for a career in cartography. It was suggested that the individual going into a small shop will need more technical preparation than a person going into a large established agency. The discussion revealed that there is considerable variation in the orientation and instruction of cartography courses. Overall, the speakers called for rigor throughout the instruction. The speakers made frequent reference to the use of the professional literature in the various courses. The essence of the presentations was that more can and should be incorporated into our cartography progra...