ReprojectME!
The Middle East Map Reprojection Utility

Overview

The ReprojectME! Program was written to make the process of reprojecting ArcView shapefiles easier to accomplish than in the ArcView Projection Utility Wizard or by using the Projector extension that also ships with ArcView.  The appropriate projection systems for the Near East were not always included in every version of ArcView.  The program supports conversion of ArcView shapefiles, ArcInfo coverages and coordinate lists in eight different ASCII text configurations; and it supports reprojection of individual points. It supports about 30 different map projections commonly used in the Middle East.

What's new in Version 2.1.5

• Version 2.1.5 added support for the Greek Grid, the Greek Military Grid (HATT), and UTM Zone 34N.
• Version 2.1.4 corrected a minor problem that kept the Output Coordinate System dropdown list from being active on some occasions when a projection file existed for a shapefile.

What's new in Version 2.1.3

• Version 2.1.3 corrected a minor glitch in how the buttone operated.

What's new in Version 2.1.1

• Version 2.1.1 corrects an error in the datum translation to and from the projections that use the Palestine 1923 datum.
• The program now supports reprojection of single coordinate pairs, for "on the fly" reprojection.
• The program now supports the Jordan Transverse Mercator projection on the new 1:25,000 scale (Arabic) topo maps.
• The program now supports the UTM coordinates from the Jordanian 1:50,000 scale topographic maps (English K737 series).  These maps use the European 1950 Datum, Egyptian version, rather than the WGS 1984 datum used by the 1:25,000 Arabic series.  This means that UTM readings from the same point on the English 1:50k and Arabic 1:25k maps will have different values.  You can use the ReprojectME! program to translate from one system to the other.
• The program has an easier user interface, which has a drop-down list for the Input Coordinate System and a second list for the Output Coordinate System.  You don't have to worry anymore about whether it's a geographic or projected coordinate system.

Download ReprojectME!

Just click on the hand icon below to download the ReprojectME! program.  It will be transferred to your system as a .zip file.  Unzip it to a scratch folder, and then run the "SetupReprojectME.bat" program.  I recommend allowing the installation to put the program in the default folder.  The installation will place the program in your "Start - Programs" list.  The program requires Windows version 98, 2000, NT, ME, or XP. 

Download ReprojectME!

Installation Instructions

1. If you have installed an earlier version of ReprojectME!, you should uninstall it, using the "Add/Remove Software" option under the Windows Control Panel.
2. Download the program, then unzip it to your desktop or a scratch folder.
3. Double-click on the "SetupReprojectME.bat" icon.
4. I recommend that you accept the default program locations.

Information on Map Projections:

Geographic Coordinate Systems:

Geographic coordinate systems measure the Earth in terms of latitude (degrees north or south of the equator), and longitude (degrees east or west of a prime meridian). These values can be expressed in degrees, minutes and seconds, or in decimal degrees. In the decimal degree system the major (degree) units are the same, but rather than using minutes and seconds, smaller increments are represented as a percentage (decimal) of a degree. The decimals can be carried out to four places, resulting in a notation of DD.XXXX, DDD.XXX. When using four decimal places, the decimal degree system is accurate to within ± 36.5 feet (11.12 m). However, because the accuracy of the fourth decimal place is often uncertain, decimal degree coordinates are often rounded to three decimal places.

Latitude is the angle measured from the earth's center north or south of a given point on the earth's surface - defined by geometric center of the earth's spin axis, the equator, lying at 000° latitude. "Horizontal" east-west lines of latitude are termed parallels, since each line each line of latitude is geometrically parallel to the next. Longitude is the east or west location of a point, measured as an angle from the earth's center east or west of a prime meridian, a given point on the earth's surface at 0 degrees longitude. Over time this point has been identified as Jerusalem, Rome, Paris, Washington, DC, and other significant places, but because of the British Royal Navy's virtual mastery of the world's oceans between the 16th and the 20th centuries, and because of the British Admiralty's exhaustively accurate nautical charts, the most commonly used system measure from the Royal Navy's principal observatory on the Thames River, just below London at Greenwich, 000° longitude. Any line of longitude can be called a meridian because it extends from the geometric center of the earth. All longitudes in this system are east or west of Greenwich.

The pure ideas of latitude and longitude are ideal mathematical overlays. Neither latitude nor longitude is an absolutely uniform unit of measure on the changing, impurely geometric earth. But their combination as a gridded network called a graticule is enormously useful. Picture a perfectly spherical grid generally holding a rough, imperfect ball; sometimes the perfect grid lies outside the ball, sometimes under its surface. The graticule has its origin at 000° latitude, 000° longitude - at the intersection of the equator and the prime meridian. We measure other celestial bodies - the moon, planets and even the sun - with a similar graticule. The shape and size of a graticule is defined by the sphere or ellipsoid upon which it is based. Recently, the use of satellites has led to more accurate measurements of the earth's shape and more accurate ellipsoids (there is a tiny thickening of the earth below the equator, a matter of yards and not miles). The most recently developed and widely used is the World Geodetic System of 1984 (WGS84). The ReprojectME! program uses this system as its base for transforming coordinates from one projection system to another--all transformations are first changed to the WGS1984 system, and then transformed again to the output projection.  See the discussion below the table of Geographic Coordinate Systems for more information about Projected Coordinate Systems.

Projected Coordinate Systems

The fundamental problem we face when we create maps is that the earth is an imperfect sphere, and our map media is flat. We have to project a three dimensional object onto a two dimensional one, and there is no way to do this that preserves all the attributes of the 3-D object accurately (even if the earth were a perfect sphere). A projected coordinate system is always based on a geographic coordinate system, which is, in turn, based on a sphere or spheroid.

Map projections are attempts to portray the surface of the earth or a portion of the earth on a flat surface. Some distortions of conformality, distance, direction, scale, and area always result from this process. Some projections minimize distortions in some of these properties at the expense of maximizing errors in others. Some projections attempt to only moderately distort all of these properties.

• Conformality -- When the scale of a map at any point on the map is the same in any direction, the projection is conformal. Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. Shape is preserved locally on conformal maps. If you are mapping a relatively small area such as a town or county, this distortion is usually negligible. The larger the area mapped, the more this distortion will affect you.
• Distance -- A map is equidistant when it portrays distances from the center of the projection to any other place on the map.
• Direction -- A map preserves direction when azimuths (angles from a point on a line to another point) are portrayed correctly in all directions.
• Scale -- Scale is the relationship between a distance portrayed on a map and the same distance on the Earth.
• Area -- When a map portrays areas over the entire map so that all mapped areas have the same proportional relationship to the areas on the Earth that they represent, the map is an equal-area map.

Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles, and areas across its two dimensions (that is, on paper). But holding these values constant requires that the actual shapes being depicted are distorted in one or more of the ways listed above.

Maps made in the Middle East have been based on a number of different map projections, including various versions of the Palestine Grid, the Egyptian Red, Blue, Purple and Extended Purple Belts, the Israel Grid, and UTM systems based on the WGS1984 and European Datum geographic coordinate systems. Each of these uses different mathematical models, datums, and so on. One can't display data from one of these projections on a map in another projection, which is especially problematic for GIS users. Themes digitized from one projection can't be displayed with those from another. In Jordan and Israel, maps are commonly published with coordinates from two or three different systems as grid lines or tick marks around the margins of the map.

Recently, some archaeologists and students who have started using GIS in the region have pondered whether to use a UTM projection as the basis of their GIS layers. I don't recommend doing this, because of the nature of the UTM projection, which I'll discuss below.

      UTM (Universal Transverse Mercator) Projection Systems

A mercator projection is a "pseudocylindrical" conformal projection that preserves shape. What you often see on poster-size maps of the world is an equatorial mercator projection that has relatively little distortion along the equator. What a transverse mercator projection does, in effect, is orient the "equator" north-south (through the poles), thus providing a north-south oriented swath of little distortion. By changing slightly the orientation of the cylinder onto which the map is projected, successive swaths of relatively undistorted regions can be created. This is exactly what the UTM system does. Each of these swaths is called a UTM zone and is six degrees of longitude wide. The first zone begins at the International Date Line (180°, using the geographic coordinate system). The zones are numbered from west to east, so zone 2 begins at 174°W and extends to 168°W. The last zone (zone 60) begins at 174°E and extends to the International Date Line. The zones are further subdivided into an eastern and western half by drawing a line, representing a transverse mercator projection, down the middle of the zone. This line is known as the "central meridian" and is the only line within the zone that can be drawn between the poles and be perpendicular to the equator (in other words, it is the new "equator" for the projection and suffers the least amount of distortion). For this reason, vertical grid lines in the UTM system are oriented parallel to the central meridian. The central meridian is also used in setting up the origin for the grid system.

Distances (and locations) in the UTM system are measured in meters, and each UTM zone has its own origin for east-west measurements. To eliminate the necessity for using negative numbers to describe a location, the east-west origin (you may hear this referred to as the zone"s "false origin") is placed 500,000 meters west of the central meridian (roughly 0.5° west of the zone boundary). Any point can then be described by its distance east of the origin (its "easting" value). Any easting value greater than 500,000 meters indicates a point east of the central meridian.

What this means is that the coordinates in each zone are independent of those in it neighbors (or any other zone).  This is not a problem with the northing coordinate, but the easting values are calculated as meters east or west from each zone's "prime meridian" of 500,000 meters.  So at the boundary between zones, the points that are furthest east in the zone on the west have larger easting values than the points furthest west in the eastern zone have.  This becomes a problem if you want to use UTM projections in a GIS system and the area you want to display is in more than one UTM zone. Jordan, for example, is mostly in UTM zone 37, but the western, most populated part, is in zone 36.  Trying to display point data (such as the sites in the JADIS system) in a GIS, using their UTM coordinates results in putting the sites that belong in the east part of the western zone further east than the sites in the eastern zone (sites in western Jordan are displayed over in Iraq), because their easting values are higher than any of the sites in UTM zone 37.  If you do it the other way around, based in UTM zone 36 instead of 37, all the sites in eastern Jordan would be displayed out in the Mediterranean Sea.

Thus, you have to reproject either the UTM zone 36 data into zone 37, or vice-versa.  If you are doing a survey and using a GPS unit, you'll have to continually remember to reproject your readings into one zone or the other.  If you take this route, it's probably best to project everything into the zone which contains the largest area in your study (so reproject UTM zone 36 into zone 37 for Jordan).  This results in less distortion in the output. However, I don't recommend doing this, because of the potential confusion.  In Israel, it's not a problem because the whole country is in UTM zone 36, but in Jordan, and most other places in the Middle East, it is a problem; these countries occupy more than one UTM zone.

     Reprojecting Image Data and Total-Station Derived AutoCAD Drawings

Another problem with projected GIS data is encountered when you want to use raster-based images, such as satellite photos or scanned topographic maps as background, and then display your own data correctly on top. Reprojecting raster images is very time consuming, and requires some expensive computer programs to do it. For GIS purposes, then, it is advantageous to start with unprojected data (that is, in decimal degrees, based on the WGS1984 system). Orthorectified satellite photographs, such as those that I've made available on my web page, are most frequently supplied in WGS1984, (unprojected) format, so your data layers have to be unprojected to display properly.

However, this is also somewhat of a problem, because unprojecting the data results in a coordinate system in decimal degrees, which is meaningless for measuring distance and area (since a degree of longitude is greatest at the equator, and is zero at the poles). Rather, it's best to tie your local, archaeological datum into a known point on your local quad sheet, and set up your site's grid system (almost always in meters) based on the location of the local datum. I set my sites in Jordan up by determining a known point on the Palestine Grid (actually the Palestine Belt projection), shoot north on the grid using a Brunton compass to establish a second point, and then measure my grid from this baseline.

If you use a total station to shoot in features and units at your site, and you've set it up so that the station is located at a coordinate on the Palestine Grid or a UTM coordinate (for example) you need to be aware that everything you shoot is going to be projected in the system from which you derived your control points. In fact, if you measure your site in meters or feet (anything other than decimal degrees), you are automatically projecting the data. Since it's completely meaningless to measure a site in decimal degrees, you'll have to project things back and forth.

So, if you use total station readings to produce an AutoCAD drawing, it's essentially already projected. If you read the drawing into ArcView, it comes in projected and will not display over your background images. All your drawing layers will have to be unprojected before they can be used over images, or all your images will have to be reprojected to the same coordinate system as that of the map from which you derived your site's datum coordinates. This means that you either have to bite the bullet and pony up the funds to reproject your background images, or you'll have to keep two versions of your data--one projected and the other unprojected. It turns out that unprojecting your drawings is easier than reprojecting the images.

The ReprojectME! Program

The ReprojectME! Program, which you can download below, was written to make the process of reprojecting ArcView shapefiles easier to accomplish than in the ArcView Projection Utility Wizard or by using the Projector extension that also ships with ArcView.  For one thing, the appropriate projection systems for the Near East were not always included in every version of ArcView (and some are still not).  

The main screen in ReprojectME! works on one layer at a time.  The user selects the layer by pressing the "Add Layer" button when the program starts.  Once a layer is selected, it may have to have its input projection system specified (especially if it was created by reading an AutoCAD drawing or .dxf file).  The user does this by selecting either a Geographic Coordinate System or a Projected Coordinate System (using the radio buttons and then choosing the coordinate system from the pull down list).  Geographic Coordinate Systems are shown in Table 1; Projected Coordinate Systems are shown in Table 2.  (A projected coordinate system is always based on a geographic coordinate system).  Once the Layer's coordinate system is selected from the pull down list, it must be set by pressing the "Set Layer Coordinate System" button.  

At this point, the user can press the "Export Layer Projected" button; the program will prompt for a shapefile name and then save the layer.  Then, you can press the "Remove Layer" button and repeat the process for as many other layers as you wish.

Two other functions are set by pressing either the "Coordinate Mode" or "Zoom Mode" buttons.  When "Coordinate Mode" has been pressed, the user can click on a spot on the map and its coordinates will be displayed in several different projections.  In "Zoom Mode," which is the default when the program starts, clicking the mouse performs various pan and zoom functions on the map layer.

     Another really useful function is activated by pressing the "Reproject Coordinate List" button.  This opens the screen shown below:

This screen operates on a list of map coordinates in ASCII format, such as might be exported from a GPS unit or a total station.  You select an input file, then indicate its format from one of the eight available:

1. ID, Y, X, Z, Note
2. ID, X, Y, Z, Note
3. ID, Y, X, Note
4. ID, X, Y, Note
5. ID, Y, X, Z
6. ID, X, Y, Z
7. ID, Y, X
8. ID, X, Y

The user then chooses the input file's coordinate system, using the same kind of controls as those on the map layer screen.  An output file is chosen (it will print in the same format as the input file), and its coordinate system is indicated.  When the "Run" button is pressed, the program calculates the new coordinates in the chosen system and writes them to the output file.  The input and output file contents are shown in the two large boxes, and their coordinate system parameters are shown as well. In the "Input File Contents" box, the user can review the contents and change them (being careful not to mess up the order of the variables indicated in the Input File Format list).

This function is very handy if you want to reproject the output from a GPS unit before you use it to create an AutoCAD drawing file.

How Can I Reproject Satellite and Aerial Photographs?

In general, reprojecting raster images can be a difficult process, because the images usually have to be rectified first, and then registered to a projection system.  Typically, commercial programs that handle these tasks are pretty expensive and have a fairly steep learning curve, so taking a different tack is frequently the best choice.  Dr. Irwin Scollar has created a program called AirPhoto, which will handle many of the tasks common to the problem.

AirPhoto makes orthophotos from scanned extreme obliques or verticals and superimposes them on scanned maps in various ways.  Color or black and white images of a number of formats can be read, or an image can be obtained directly from a scanner driven by the program.  Up to four maps may be combined to obtain a result for pictures which show data contained within more than one map.  Photomosaics may be made from multiple color or black and white images. AirPhoto also offers a selection of full color image processing routines and use of an unlimited number of control and calibration points.  AirPhoto offers calibrated mapped output in 42 national, international or arbitrary coordinate systems (but not the Palestine or Egyptian projections).  When an output image has been calibrated, the position of the mouse cursor is shown in in the units of the chosen grid system in a status bar at the bottom of the image.  A file with the information required by a Geographic Information System is written containing the parameters which each of three currently supported types of GIS require namely: ArcInfo/View, MapInfo and Idrisi, plus GeoTiff for other GIS programs which support that standard.  All grid systems can be converted to and from GPS latitude / longitudes or coordinates may be displayed directly in GPS lat/lon.  Datum transformation between all systems via a GPS intermediate step is available.  AirPhoto is a non-profit shared cost program whereby each registered user shares a small part of the cost of its production and maintenance.  No charge for programming time is made.  The permanent registration fee is Euro 270.00 (about US$ 245) when paid by credit card.  You can download an evaluation version of the AirPhoto program from

1. http://www.uni-koeln.de/~al001/airphoto.html.  Cologne, Germany.
2. http://wings.buffalo.edu/anthropology/BASP/airphoto.html.  SUNY, Buffalo, USA.
3. http://super3.arcl.ed.ac.uk/baspmirror/airphoto.html University of Edinburgh, Scotland.