Understanding Maps

Libya Maps

Although Libyan law stipulates that Sahara travellers must be accompanied by a local desert expert, one still needs to use specialist maps and GPS devices, as none of the local experts knows all (or even a fraction) of the locations of the various sites of interest in the Sahara. In fact, even the best map in the market only features a rough guide to the locations of a tiny selection of the hundreds of thousands of cave drawings and rock engravings scattered across the desert; and therefore complete maps of the Sahara are yet to appear.  

These pages will attempt to collect information, resources, links and maps relating to Libya and the Sahara. There are a number of GPS websites currently attempting to build a global database of GPS coordinates, based on public contributions. Our current collection so far includes a number of maps originally produced by the US Army Map Service and used here courtesy of the University of Texas Libraries at Austin; which although are not as detailed as, say, EWP's Jabel Acacus Map, they still nonetheless show the main features of the landscape, tracks and (of particular importance) the old local names, some of which have now disappeared from memory. They also cover a large area of Libya.

We have also customised a number of interactive maps using javascript code from openstreetmap.org and tiles from google.com. These include an interactive map showing the main sites of interest in Libya; a distance calculator (which measures distance between any two points on the planet); coordinates finder (which gives the coordinates of any place on earth simply by one click); and a photo map.

What is a topographic map?

Topographic maps show the shape and the main features of the land. The topography of any given area is shown by contours or brown lines representing different elevations:

1. thick brown lines (Index Contours) define the actual feature and give its height.
2. thin brown lines (Interval Contour) give the variation in elevation: very close lines mean steep slopes, lines with large gaps indicate gradual slopes.

What is scale?

It is the ratio representing the relation between a distance on a map and its corresponding distance on the land. For instances, a scale of 1:100,000 means that 1 unit on the map is equal to 100,000 identical units on the land. Use the link to Scale Calculator (see below) to find the actual value of any scale unit.

Map Scale Calculator:

Scale Calculator: beg.utexas.edu/GIS/tools/scale2.htm

Using the tool available at the above link, you can calculate the actual value of any scale unit by typing only the representative fraction of your map: for example: if the map scale is 1:100,000, enter 100000 in the box provided.

Examples:

Navigation

Using Map & Compass:

egsc.usgs.gov/isb/pubs/factsheets/fs03501.html

This guide provides detailed instructions for how to use a map and a compass to find your way around and determine the direction from one point on the map to another.

The Royal Institute of Navigation (RIN):
rin.org.uk/

GeoNames

GeoNames is an online geographical database of Latitude and Longitude coordinates of geographical places from any country in the world. The database is licensed under the Creative Commons Attribution 3.0 License, and currently includes over eight million placenames that are available for download free of charge, from: geonames.org

http://www.geonames.org/

The World of The Landsat Satellites & Their View of The Earth

The Landsat's mission is to collect, archive, and distribute data of all the Earth's land surface.
zulu.ssc.nasa.gov/mrsid/mrsid.pl

The first Landsat was launched on July 23, 1972, to initiate a new era of Earth observation from space for non-military purposes. The information collected  is now the standard for Earth observations. Landsat circa 1990/2000: click on the map to zoom in/out, or 'Select Image' from the menu below the map and click on the desired region on the map to display the image in a new window.

NASA's World Wind

Download World Wind For Free, directly from worldwind.arc.nasa.gov/

NASA's open-source-program World Wind is similar to Google Earth - except in that it is free -   very handy indeed if you just want to publish an actual image in your website, rather than having to link to it via embeded script. The Landsat Global Mosaic (except for i-3 visible layer), Blue Marble, and the USGS raster maps and images are all Public Domain. (Please note that not all data provided by the add-ons is Public Domain). The downloded program includes the required: .NET runtime, and the managed DirectX library. For download: worldwind.arc.nasa.gov/ ;  for user manual: learn.arc.nasa.gov/worldwind/ .

NASA's Global Maps:

Follow the link (earthobservatory.nasa.gov/GlobalMaps/)
then click on any map to see the data moving through the year, month by month.

Solar & Lunar Data:

Sun & Moon Rise & Set, Eclipse Data, Phases of the Moon, Day & Night, Navigational Star Chart, and more:
usno.navy.mil/USNO/astronomical-applications/data-services

This link provides tools and tables for finding times for sunrises and sunsets, moonrises and moonsets, eclipse data, phases of the moon, hours of day and night in different locations, navigational star chart, and many more related data and calculators.

Moon Phase Images:
tycho.usno.navy.mil/vphase.html

View the phase of the moon for any date and time between the years 1800 and 2199 AD.