Professional-Quality Digitized Maps

If geography has anything to do with your project, then accurate, detailed digital maps are essential. Whether you are publishing in a magazine, a book, or on the Internet, there are three steps involved: Acquiring the Image, Annotating the Map, and Formatting the File.

Acquiring the Image
The first step is to get your map digitized. There are several approaches, depending on whether you start with a map printed on paper, a digitized map downloaded from the Internet, or digitized maps stored on a CDROM. The examples below were produced from these sources. They are shown actual size.

Scanning a Paper Map
A USGS 7 1/2' quadrangle is about the size of an unfolded newspaper. Flatbed scanners usually aren’t that big. You’ll need a scanner with a removable top, so you can lay the map on the glass without having to fold it. Then put a big book on top of the map, to press it flat against the glass. Encyclopedias, high school and college yearbooks are about the right size.

If the area of interest includes a boundary between two or more maps, you can make a composite map by cutting away the edges and carefully taping the maps together with transparent tape. The seam will show, but it would show anyway using the other methods.
scanned from a paper map
Figure 1. Image Scanned from a Paper Map
When scanning your map, you have to line it up very carefully so that the area of interest is over the glass, and north is the top of the page. Most maps have vertical and horizontal lines which help with this alignment.

After scanning your map, you may need to crop the image to show only the area of interest. Also, you may need to convert the file type if the scanner doesn’t give you JPEG or GIF. The software that came with your scanner usually does this. Otherwise, GraphicConverter handles the conversions with great aplomb.

The image from a printed map is friendly and highly detailed. It also captures any marks, folds, or imperfections that exist on the printed map.

You may discover that north isn't lined up exactly with the top of the map. In this case, edit the map with Photoshop Elements and use the Straighten tool to correct the alignment.

Some USGS topographic maps are darker than others. If your scanned image includes a seam between a light map and a dark map, use the following steps to make the brightness uniform.
  1. Open the file in Photoshop Elements.
  2. Use the rectangular marquee to select the area that is too dark. If the boundary line isn't quite horizontal or vertical, you need to rotate the image to bring it into alignment.
  3. Edit → Copy
    • Be careful not to deselect the area after copying.
  4. File → New
    • The new file will be the same size as your selection.
  5. Edit → Paste
    • Paste into the new file.
  6. Enhance → Adjust Brightness/Contrast
    • Adjust the brightness so that it matches your original file.
  7. Select → All
  8. Edit → Copy
  9. Click on the original file. The area to be adjusted is still selected.
  10. Edit → Clear
  11. Edit → Paste Into
    • Paste into the original file.
  12. View → Actual Pixels
    • Scroll down to the area you pasted into.
    • If the brightness isn't right, undo the Paste Into and go back to step 6.
    • If the images aren't lined up, use the arrow keys to nudge the selection left or right.
  13. View → Fit on Screen
    • Take one last look, before you save the file.
    • If you had to rotate the image, crop the angled sides.
  14. File → Save
Downloading a Map from the Internet
Digitized USGS topographic maps can be downloaded for free from various sources. My example is from the Arizona Regional Image Archive.

Current and prior editions of topographic maps have been scanned in PDF format by the US Geological Survey. They provide excellent detail, some requiring color adjustment.

You’ll need to crop the image to show only the area of interest. Then you might have to convert the file type to JPEG or TIFF or GIF.
Figure 2. Image Downloaded from ARIA
If your area of interest includes the boundary between two or more maps, you can paste pieces of maps together using an image editing program. Or buy the maps on paper, cut them and tape them together, and scan them as described above. You may have to adjust the brightness if one map is darker than the other.

Exporting a Map from a CDROM
Maps digitized on CDROMs are seamless, so you can just select the area of interest and export the map to disk. My example is from the National Geographic maps of Arizona, along with the TOPO!® software (unfortunately, out of print).

The image is a screen dump. It shows exactly the area you selected, and is annotated around the edges like a topographic map. The size and resolution are O.K. for posting the map on a web page, but the resolution is not fine enough to print the map for publication.
exported from a map on a CDROM
Figure 3. CDROM
© National Geographic
For an example, see

TOPO! can download waypoints and tracks from a GPS and display them on the map. Use this feature to show actual routes and locations, but then re-draw the map for publication using one of the methods above.

Annotating the Map
Using the digitized map as a background image, add other notations in the foreground. This can be done in Microsoft PowerPoint or another image editing program.
Figure 4. Map Annotated with PowerPoint
When Using PowerPoint

Insert:   Picture → From File ...

Browse to find your digitized map. It will probably be too large. Some images are too large to be displayed in PowerPoint, in which case you’ll have to save a cropped or resized version to make it fit.

Adjust the size using the Image Size command from the Image menu. Center the map on the slide using the scroll bars. When the size and position are right, save the PowerPoint file. The digitized map is your background image.

Be creative about adding annotations.

Save. You are now at step 1 of Formatting the File (see below).

Formatting the File
If you are posting your map on a web page, save it as a GIF or JPEG, 72 dpi resolution, so that it won’t take too long to load on the screen.

Magazines and books need a high-resolution graphic file. The following process will convert a PowerPoint slide into a TIFF graphic, either color or grayscale. For converting the file types you will need a program such as GraphicConverter.
  1. Edit the map in PowerPoint. You may want to adjust the brightness and contrast, then add annotations such as routes, places of interest, etc. Print Preview can show you what the map will look like, but wait until step 12 to actually print it.
  2. PowerPoint:   Preferences → Save → Save slides as graphic files
    Save current slide only.
    Advanced resolution settings:
    Dots per inch (dpi) 1600. The maximum dpi for pictures in a book is 600. However, Adobe Photoshop Elements is slightly better than PowerPoint at preserving details in the image. For the best image quality, save the image at 1600 dpi (the maximum) in PowerPoint and then adjust it to 600 dpi later in Adobe Photoshop Elements.
    uncheck "Compress graphics files".
  3. PowerPoint:   File → Save As
    Macintosh Picture (PICT) or Portable Network Graphics (PNG)
    • The PICT format captures the full details. But for some mysterious reason, a PICT file saved by PowerPoint can’t be read by Photoshop Elements. Alas, recent versions of PowerPoint left out PICT as a file format in Save As. The only work-around I know is to keep an older Mac which runs an older version of PowerPoint. See To Upgrade or Not To Upgrade?.
    • The PNG format also captures full details, but its resolution isn’t as high as PICT.
    • Try them both. If PNG gives you acceptably fine detail, use it.
  4. Open the PICT or PNG file in GraphicConverter.
    • As its name implies, this program converts graphic files between various formats.
  5. GraphicConverter:   File → Save As
    Options → Compression → None
  6. GraphicConverter:   File → Close
  7. Open the TIFF file in Adobe Photoshop Elements.
  8. Photoshop Elements:   Image → Crop
    • Crop headers, footers, white space: everything but the map itself.
  9. Photoshop Elements:   Image → Image Size
    • You may need to change the size of the image for printing.
    • Set the resolution at 600 dpi.
  10. Maps deserve to be printed in color!
    But if your publisher only prints them in black and white, you’ll need to perform this step:
    Photoshop Elements:   Image → Mode → Grayscale
  11. Photoshop Elements:   File → Save
  12. Photoshop Elements:   File → Print
    • Use plain paper in a high-resolution photo printer. If it looks good on plain paper, it will also look good on glossy paper in a book or a magazine.
  13. Photoshop Elements:   File → Close
  14. Look at the map you printed in step 12. Did it turn out O.K.?
    If there are any problems, go back to step 1 and fix them in PowerPoint.
  15. PowerPoint:   File → Save
  16. PowerPoint:   File → Close

Copyright Issues
USGS-authored or produced data and information are in the public domain.

For maps created with TOPO! the National Geographic copyright notice must appear. With any mapping software, read the license carefully and get permission from the company when it is required.

© Copyright 2016, by Ted Tenny.  All rights reserved. updated September 9, 2016