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Results for “Cartographic Perspectives”

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5 recordsLinked to original sources
USGS2012

A program for handling map projections of small-scale geospatial raster data

Scientists routinely accomplish small-scale geospatial modeling using raster datasets of global extent. Such use often requires the projection of global raster datasets onto a map or the reprojection from a given map projection associated with a dataset. The distortion characteristics of these projection transformations can have significant effects on modeling results. Distortions associated with the reprojection of global data are generally greater than distortions associated with reprojections of larger-scale, localized areas. The accuracy of areas in projected raster datasets of global extent is dependent on spatial resolution. To address these problems of projection and the associated resampling that accompanies it, methods for framing the transformation space, direct point-to-point transformations rather than gridded transformation spaces, a solution to the wrap-around problem, and an approach to alternative resampling methods are presented. The implementations of these methods are provided in an open-source software package called MapImage (or mapIMG , for short), which is designed to function on a variety of computer architectures.

Cartographic Perspectives↗
USGS2009

Data layer integration for the national map of the united states

The integration of geographic data layers in multiple raster and vector formats, from many different organizations and at a variety of resolutions and scales, is a significant problem for The National Map of the United States being developed by the U.S. Geological Survey. Our research has examined data integration from a layer-based approach for five of The National Map data layers: digital orthoimages, elevation, land cover, hydrography, and transportation. An empirical approach has included visual assessment by a set of respondents with statistical analysis to establish the meaning of various types of integration. A separate theoretical approach with established hypotheses tested against actual data sets has resulted in an automated procedure for integration of specific layers and is being tested. The empirical analysis has established resolution bounds on meanings of integration with raster datasets and distance bounds for vector data. The theoretical approach has used a combination of theories on cartographic transformation and generalization, such as T??pfer's radical law, and additional research concerning optimum viewing scales for digital images to establish a set of guiding principles for integrating data of different resolutions.

Cartographic Perspectives↗
USGS1993

A temporal comparison of forest cover using digital earth science data and visualization techniques

Increased demands on forest resources and the recognition of old-growth forests as critical habitats and purifiers of the atmosphere have stimulated attention to forest harvest practices in the United States and worldwide. Visualization technology provides a means by which a history of forestry activities may be documented and presented to the public and decisionmakers. In this project, landsat multispectral scanner and thematic mapper images, acquired July 7, 1981, and July 8, 1991, respectively, were georeferenced, resampled, enhanced, and draped over U.S. Geological Survey 30-meter digital elevation models. These data then were used to create perspective views of portions of Mt. Hood Forest, Oregon. The "fly-by" animation (produced by rapidly displaying a sequence of these perspective views) conveys the forest cover change resulting from forest harvest activities over the 10-year period. This project shows the value of combining satellite data with base cartographic data and earth science information for use in public education and decision-making processes.

Pecora 12 Symposium↗
USGS1984

RESEARCH FOR THE USGS DIGITAL CARTOGRAPHY PROGRAM.

The U. S. Geological Survey National Mapping Division (NMD) has been conducting research and development in digital cartography since the early seventies. Since 1977 there has been an acceleration of activities associated with establishing a National Digital Cartographic Data Base (NDCDB). The NMD Office of Research is primarily responsible for fundamental and applied research together with systems development and technical standards to support the digital cartographic program. Three phases of development have been defined - the current system, an optimum system that can be built with current technology, and a future system that could be defined after some basic research is completed. Some of the current projects related to automated data capture, editing, coding, and structuring are described together with a perspective on future directions. The overall rationale is to develop a very large integrated system that will support a NDCDB and lead toward operational geographic information systems.

Conference Paper↗
USGS1984

Computer-assisted cartography: an overview.

An assessment of the current status of computer-assisted cartography, in part, is biased by one's view of the cartographic process as a whole. From a traditional viewpoint we are concerned about automating the mapping process; from a progressive viewpoint we are concerned about using the tools of computer science to convey spatial information. On the surface these viewpoints appear to be in opposition. However, it is postulated that in the final analysis, they face the same goal. This overview uses the perspectives from two viewpoints to depict the current state of computer-assisted cartography and speculate on future goals, trends, and challenges.-Authors

South African Journal of Photogrammetry, Remote Se↗