Method for Making Digital Photos of Topographical Maps
for EVA route printing in the absence of a scanner.

Route planning for EVA is customarily done on a topographical map, with fine pencil lines, and finely marked waypoints. It is very handy to use a map with big, bold marks that can be easily read while enroute, in a spacesuit. Unfortunately, that leaves one's topo map heavily marked up, folded many times; and a full topo is inconvenient to deal with on EVA. It is good for several crew members to have the same map, for various reasons. This method is a way of acquiring a photo of a portion of finely marked topo map, and printing that photo close to scale so that it may be marked boldly, and copies caried by several crew members. A scanner would be the preferred approach, if available, but this is a workable substitute.

This method should work for any digital camera, with any focal length lens (or degree of zoom). You may have to adjust your resolution, as we will see. I used 2048 x 1536

1. I created a mask, with a cutout exactly 8 1/2 by 11 inches, from a file folder (red; it is stored on the wall beneath the southeast large round window)
   
   
2. Using this mask, or one you create, place the mask on the area of the topo map you are concerned with. The map can be on the floor, or on the table.
   
   
3. The first time you do this, place a ruler along one edge of the open area of the mask, with divisions visible. After you have set up your system for a given camera, you will not need the ruler
   
   
4. Stand over the map (use a chair if the map is on the table, and adjust the zoom or your height until the open area just fills your view screen. Do not use a wide angle setting, as that may introduce spherical distortion (curving straight lines somewhat). Be sure the ruler is visible in your first tests.
   
   
5. Take the picture, transfer it to a computer, and open it.
   
   
6. Now print it as close to 8 1/2 by 11 finished size as you can. My camera (Olympus C-3000) prints real sized at its 2048 x1536 resolution setting. You may want to adjust brightness and contrast for best clarity before printing.
   
   
7. Inspect the printed image. Place the real ruler alongside the image of the ruler. The divisions should line up exactly, or within 1/32 inch or so.
   
   
8. If the divisions line up, you have a same scale image of the map section. If not see the next heading. Mark over the thin pencil lines on the printed map, and write the waypoints in boldly, so you can easily see it from a foot or two. This copy should not be used for precision navigation, in the dark, in dangerous terrain, etc., where navigation errors may be critical. It is fine for estimating distances, grid references, and bearings in the field, as an aid to dead reckoning, and for keeping track of your progress along your route. The ink and paper are affected by water, protect it from wetness. Remember, your original route may not be accurately plotted, and the original map may not fully correspond to reality. Navigation should always cross correlate map data, GPS data, dead reckoning data, and direct observation of features and landmarks.
   
   
9. If your image of the ruler is larger or smaller than the real ruler, you have to adjust the size at which you print. You can do that by scaling the image itself in your photo viewer software, or Photoshop, or many graphics applications that will open JPGs. You can also adjust by scaling in the printing dialog, if your computer and printer allow it. It is best to adjust the scale on the computer rather than by moving the camera, because the scaling on the computer is easily repeatable. Record what settings you use so you can re-create them. As long as the 8 1/2 by 11 opening just fills your view finder, you have a known starting place.

When your imaged ruler closely matches the actual ruler, go back to step 8. You could also adjust the resolution which changes the size of the image, as another variable.

Printing paper and ink are scarce resources on Mars, but so are topo maps. Used very judiciously, this method can conserve topo map quality, at a modest expenditure of resources, and generate mulitple identical route maps for crew use. The digital image can be carried in a camera for backup, and viewed (zoomed in) as needed.