GEOG1140

GIS for Human and Physical Geography

An information system that is designed to work with data referenced by spatial or geographic coordinates. In other words, a GIS is both a database system with specific capabilities for spatially-referenced data, as well as a set of operations for working [analysis] with the data.

(Star and Estes, 1990) A system for capturing, storing, checking, integrating, manipulating, analyzing and displaying data which are spatially referenced to the Earth.

(Chorley, 1987) Automated systems for the capture, storage, retrieval, analysis, and display of spatial data.

(Clarke, 1990) A system of hardware, software, and procedures designed to support the capture, management, manipulation, analysis, modeling and display of spatially-referenced data for solving complex planning and management problems.

(NCGIA lecture by David Cowen, 1989) An integrated package for the input, storage, analysis, and output of spatial information... analysis being the most significant. (Gaile and Willmott, 1989)

GIS are simultaneously the telescope, the microscope, the computer, and the xerox machine of regional analysis and synthesis of spatial data. (Abler, 1988)

From: David Mark <dmark@sun.acsu.buffalo.edu> Can we come up with a definition of GIS that would provide a "truth in advertizing" product defnition for what software can be advertized as being a GIS, and what cannot,a definition which, when applied to all the packages that we agree are GISs returns "TRUE", and for the others returns "FALSE".

From: dmarble@magnus.acs.ohio-state.edu (Duane F Marble) One of the distinctions is the ability to do overlay. Not draw two things on top of each other, but the logical operation. The creation of buffers via computation is also closely related. The distinction is between mapping and analysis.

From: Mike Ruth <ruth@spot.com>

GeoTIFF format is a non-proprietary geographic TIFF format. The purpose of GeoTIFF is to provide information that lets raster imagery (scanned maps, satellite images, results of geographic analysis, etc) be read automatically into correct position and scale within many GIS softwares. GeoTIFF implements a tag structure which embeds the geographic information methodically and interoperably (and invisibly to most users) inside the TIFF file.

Unlike many other formats, GeoTIFF is non-proprietary, supported by open, public domain utilities. The specs are maintained by NASA-JPL on the WWW and there are free software utilities written by several authors, free for the downloading. Major imagery utilization software developers, (including ESRI, Intergraph, Mapinfo, Softdesk, ERDAS, PCI, and others) and commercial imagery data providers (NASA-JPL, SPOT, Space Imaging, USGS, and others) participated in open cooperation to design the format.

GeoTIFF is now read by many GIS platforms, including all the recent releases of major GIS platforms in common commercial use. The main advantage to the user of GeoTIFF is that the *same image file* can be read by different, unrelated GIS's. Thus the end-user does not have to translate for each application - no duplication of files, no entering of strings, coordinates, generation of proprietary control files, etc. Most GIS's implement a point-and-click interface which most clients really appreciate. Clients who may not know anything about a "projection" or "datum" can easily get their imagery loaded in their GIS in correct position and scale.

TIFF readers that do not know about the GeoTIFF tags simply ignore them, and treat the TIFF image as any other ungeographic TIFF. The tags are used only by softwares that know where to look for them.

The official homepage of GeoTIFF is at NASA-JPL:

http://www-mipl.jpl.nasa.gov/cartlab/geotiff/geotiff.html

SPOT maintains a WWW pointer page to a variety of GeoTIFF resources: