ABSTRACT

The main purpose of this website is to make available to the dedicated enthusiast of Joshua Tree National Park large displays of aerial photographs (fotos) and topographic maps (topos) at the following meter-per-pixel resolutions: 01, 02, 05, 10, and 25. The data for these displays are being acquired using the TerraService-USA OpenGIS Web Map Server (OGMS) jointly developed by the U. S. Geological Survey (USGS) and the Microsoft TerraService (MSTS). USGS and MSTS have collaborated to provide on the web a huge data bank of graphic foto and topo material at various resolutions in the form of rectangular areas whose boundaries coincide with grid lines of the Universal Transverse Mercator (UTM) Global Positioning System (GPS). GPS units (receivers) and GPS-compatible maps are very useful for situations where accurate knowledge of location is required, including driving, hiking, and climbing. We briefly discuss UTM, MGRS, and UGPS, three standard GPS grid reference methods which employ latitude measurements incommensurably with metric measurements. Proposals are presented for purely metric normalizations of UTM and MGRS, and for a spectrum of new purely Metric Global Positioning Grids (MGPG) including specifically the Metric Grid Reference Window (MGRW) facility which is superior to MGRS in providing unicity of truncated addresses over large areas when used with large scale customized MGPG maps. Over a background showing the Cylindrical Mercator Projection of the world, a display of one third of the NUTMAP (Normalized UTM Map) provides a graphic visualization of the NUTMAP and the incommensurability of latitude measurements with metric measurements. The thick horizontal green lines indicate the approximate locations of those curved latitude lines at multiples of 8-degrees which form the horizontal boundaries of the UTM/MGRS Grid Zones (or REGIONS) while the thin horizontal red lines indicate the exact locations of the metric grid lines at multiples of 1000 kilometers which form the straight horizontal boundaries of metric DOMAINS. A list of Global Positioning System references is provided. Dale dePriest provides an excellent description of How Your GPS Works. Attention is called to certain GPS units, GPS-compatible maps, and digital cameras. The website contains many links as well as a copious supply of GOOGLE search engine windows for general inquiries.

MGRS replaces a pair of UTM digits by a pair of letters in order to provide high-order truncated addresses which have large areas of unicity, and its use by the United States Armed Forces was directed by the U. S. Joint Chiefs of Staff in 1949 according to an email I received from Tom Terry of the USNG (United States National Grid). An associated display shows clearly that MGRW Case #2 windows can provide a separation between homonymous neighbors (repeats) of truncated addresses which is twice as great as that provided by MGRS without the replacement of digits by letters and at a cost of only one additional character in the truncated address.

  NOTICE  
Developments and refinements for this website will be posted here from time to time.

DEVELOPMENTS
2003.05.26.  The USGS/MSTS foto and topo map materials on this website are being completely reconstructed using the OpenGIS Web Map Server. Material is now being collected at 01-meter, 02-meter, 05-meter, 10-meter, and 25-meter resolutions in the form of 1000-pixel-square JTNP tiles which represent, respectively, 01-km, 02-km, 05-km, 10-km, and 25-km square areas. At the 25-meter resolution, all 12 of the 25-km square areas within the three 100-km square MGRS SQUARES NT, PT, QT are presented so as to include Parker AZ although the two MGRS SQUARES NT and PT together entirely contain JTNP. However, only selected areas of interest within JTNP itself are presented at the four higher resolutions.

REFINEMENTS
2002.10.13.  The metric grid systems are based on the metric system (see Wildi, Nelson), which has been adopted as the predominant measurement system of all industrialized nations in the world with the glaring exception of the United States. The meter was originally intended to be 1/10,000,000 of the distance between the equator and either pole measured along a longitudinal meridian. The actual measurements were made over a period of seven years during the French Revolution under extremely difficult conditions, as is recounted in the scholarly text The Measure of All Things, ISBN 0-7432-1675-X, Ken Alder, © 2002, which indicates that due to slight errors the distance from equator to pole is now reckoned to be approximately 10,002,000 meters ( 10,002,290-Alder, 10,001,966-Humerfelt). Since the polar regions are cartographically treated by the Universal Polar Stereographic (UPS) projection, I have chosen to arbitrarily terminate the Universal Transverse Mercator (UTM) graphics on this website at 10,000 kilometers from the equator.

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