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For most applications in a smaller worldview, such as counties or
basins, is to generally use a UTM, or Universal Transverse Mercator
projection that works best in the continental United States. You might
also choose to use an option for State Plane projections. The projection
is simply a mathematically calculated way to plot XY's or to basically
"flatten the earth". 
The Mercator map projections, on a larger scale, such as viewing the entire US or other countries of the world together on one map, preserves the property of direction and the shape of features quite well, but sacrifices accurate distance and area. So when analyzing or using data you are working with, and direction and shape accuracy are critical, the Mercator map projection may be the preferred projection for that project. Again, any errors will only be noticeable if one is trying to view large areas such as the United States or Canada.
Another common map projection for the United States to be used for larger scale projects, is the Lambert Conformal projection which preserves shape and maintains accurate distance in the East-West direction for the lower 48 states, but these qualities are achieved at the expense of direction and area. So when analyzing or using data where shape and distance accuracy are critical, the Lambert Conformal projection may be the preferred projection for that project.
With the advancement of the Internet, many government websites now offer a tremendous amount of cultural data that can be added to your map to easily depict city boundaries, rivers, lakes, roads & highways, rail roads, county boundaries and a host of other data that would have special interest to the geologist or engineer who are evaluating prospect areas.
The following are some websites you might consider for obtaining cultural data that can be easily imported directly into your mapping software, and most of the websites identified are governmental agencies that offer free data downloads. There are also a tremendous amount of websites that exist to obtain pipeline, aerial photographic, satellite and other topographic products that can help the geoscientist with a better understanding of what is going on at the surface of prospect areas.
www.geo.ou.edu for many diverse cultural features for the state of Oklahoma
www.search.usgs.gov for USGS GIS data for all states in the United States
www.nationalatlas.gov/atlasftp.html for US GIS data
www.esri.com/data/download/index.html for US GIS data
www.census.gov/geo/www/cob/st2000.html for US cartographic boundary files
www.asprs.org the Imaging and Geospatial Information Society
www.terrainmap.com/rm1.html for Digital Terrain Modeling & Mapping Data
http://arcdata.esri.com/data/tiger2000/tiger_statelayer.cfm?sfips=40 for Downloadable shape files for census and demographics information
www.landvoyage.com for downloadable topographic, aerial and satellite images for the entire US
Expand your horizons and pick up a copy of ArcView to enable you to manage and analyze your corporate assets within one database. Let CEC Energy Consultants help take your company to the next level.
Back to January 2004 Newsletter
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