GPS for Dummies.pdf - Engineering Surveyor

250Part III: Digital Mapping on Your ComputerOziExplorer and World War IThe 1980s movie Gallipoli recounted theAustralian experience of fighting the Turksduring World War I. Although long before thetime of computers and mapping software, WWIalso has a link to OziExplorer.Howard Anderson wrote a fascinating article onusing OziExplorer to locate old World War Itrench lines in France and Belgium. The remainsof the trenches are long gone, but by using oldmaps from the period, scanning them, and addinggeoreferenced data, Anderson was able toclearly determine where the trenches were dugduring the early 1900s.After he had scanned and georeferenced theold military maps, Anderson used OziExplorer todraw GPS tracks on personally created digitalmaps to trace the outlines of the trenches. Healso used waypoints to identify military and landfeatures. Anderson then took the tracks andwaypoints and overlaid them on a modern mapin OziExplorer. This revealed where the longagowar emplacements once stood. Anderson’slast step was to visit France with a GPS receiverand his old and modern maps. He found that,with relative accuracy, he could stand on thesite of a trench where his grandfather hadfought over 85 years ago.To read Anderson’s complete account, whichhas historical insights as well as his experiencesin using OziExplorer, visit the WesternFront Association’s Web site at www.westernfrontassociation.com/thegreatwar/articles/trenchmaps/stand.htm.If you have a map that’s made up of multiple image files, such as a large mapcut up into a series of smaller maps, you’ll need to stitch them and a single,large image. Commercial graphics program such as Adobe Photoshop andJasc Paint Shop Pro have commands for combining files. You can also manuallystitch together images with Microsoft Paint by using the Paste From commandof the Edit menu. Here’s a link to a great tutorial on stitching together scannedimages: www.sibleyfineart.com/index.htm?tutorial—join-scans.htm.Step 2: Edit the mapAfter you successfully scan the map, make any last-minute changes to theimage. This could include Adjusting the brightness and contrast to make the map more readable. Adding symbols or text information. Removing the white space (or collar as it’s known in map-speak) thatsurrounds the map.Use your favorite graphics program to make any final edits to the map image.After you’re through, save the map as a TIFF, PNG, or JPG file to reduce howmuch disk and memory space the image takes up. (These compressed fileformats are more space-efficient and memory-efficient.)