Saving Aerial Photos

After you have an aerial photo or map displayed onscreen, you can save the image to use with other programs:

• From the File menu: Choose Copy to Screen.jpg. This saves a copy of the aerial photo or map currently displayed onscreen to a file named Screen.jpg in the same folder that USAPhotoMaps is installed in.
• Print Screen: Press the Print Screen key to save the current image to the Clipboard. If you want to save only a portion of the map or aerial photo that appears onscreen.
• BigJpeg: Use the BigJpeg utility. Doug Cox has a free utility that creates a single, 1-meter resolution, JPG format graphics file from a photo or map. You define the boundaries of an area you want to save in USAPhotoMaps and then run BigJpeg to create the graphics file. You can download BigJpeg, with complete instructions, at http://jdmcox.com.

Creating and Using Multiple Map Files

USAPhotoMaps uses a map file to name areas that have downloaded aerial photo or map data. A map file is a bookmark for a general vicinity or location. For example, you might have downloaded aerial photos for the entire Grand Canyon. Instead of scrolling to view photos at each end, you could create two map files, one called North Grand Canyon and the other South Grand Canyon.
To create a map file bookmark

1. From the File menu, choose New Map File.
2. In the New Map dialog box that appears, enter the name of the map file and the coordinates that you’d like to bookmark.
3. Click OK.

After you create a map file, select it, and USAPhotoMaps displays the aerial photo or map associated with that area.
To select and display a new map file

1. From the File menu, choose Open Map File.
2. Select the name of the map file to load.
3. Click OK.

The area that you bookmarked is now displayed onscreen. Map file bookmarks are used to identify a general location. They shouldn’t be used for marking a very specific set of coordinates, such as a GPS waypoint.

Entering text in USAPhotoMaps

After you have an aerial photo displayed, you can add text labels to different
features when the image is displayed at the 1- or 2-meter zoom levels. To enter
a text label
1. Move the mouse cursor to the location where you want the text to start.
2. Hold down the Shift key.
3. Move the cursor in the direction you want the text to be aligned. A line is temporarily drawn as you move the cursor. For example, if you draw a line at a 45-degree angle, the text will flow at a 45-degree angle.
4. Release the Shift key.
5. In the dialog box that appears, type in the text label and click OK.
A list of all the text labels is displayed.
Text in a label is limited to 60 characters and can be edited or deleted by choosing Text➪List.
You can set the text color by choosing File➪Preferences➪Colors. The Color Preference dialog box, which isn’t all that intuitive, uses a series of radio buttons that correspond to red, green, and blue values. Your best bet for choosing a color you’d like is to enter some text and then display the Color Preference dialog box. When you select different combinations of color radio buttons, the text you entered changes color.

Enhancing contrast in USAPhotoMaps

One of the things you’ll notice as you start to view aerial photos is that the contrast might be lighter or darker with certain images. This has to do with the amount of sunlight when the photo was taken and the background color of the terrain.
To enhance less-than-optimal contrast, USAPhotoMaps has a nifty feature that lets you adjust the contrast of the photos displayed onscreen by either lightening or darkening them. This can really enhance detail in a photo.
You can control the contrast of a photo by using these keys:
_ Lighten: Press the B key.
_ Darken: Press the D key.
You can also set contrast by selecting Brightness from the View menu, including restoring the contrast back to its default setting.

Zooming in and out

You can zoom in and out on an aerial photo or map to see more detail or get a larger, big picture view. For zooming, use these keys:

• Zoom in: Press Page Down or the plus (+) key.
• Zoom out: Press Page Up or the minus/dash (–) key. The current zoom level appears in the window title bar, so you always know how far you’ve zoomed in or out.

The zoom level on the window title bar displays the resolution of the image. If the resolution is 4 meters-per-pixel, each pixel (picture element) onscreen represents an object 4 meters in size. (Remember that a meter is roughly a yard.) Smaller numbers mean higher resolution and greater detail. For example, 1 meter-per-pixel resolution means that you can distinguish objects on the ground that are one meter in size. How far you can zoom in and out on an image depends on what type of map you’re viewing.

• Topographic maps: 4, 8, 16, or 32 meters-per-pixel
• Aerial photos: 1, 2, 4, 8, 16, 32, or 64 meters-per-pixel If you’re switching back and forth between aerial photos and topographic maps, use either a 4 or an 8 meters-per-pixel zoom level. This will give you close to a one-to-one size representation of features on the aerial photo and the topographic map.

Moving around the USAPhotoMaps

You’ve probably noticed that USAPhotoMaps doesn’t use scroll bars like other Windows programs. Not to worry; you can still move around in a photo or map by using the keyboard navigational arrow keys:
If you see gray squares while you’re scrolling, map data has yet to be downloaded for that particular area. Figure above shows gray squares with aerial photo data that hasn’t been downloaded. Here are two ways to fill the squares with map or photo data:

• From the File menu, choose Download Map Data➪Fill Screen.
• Press the F key.

USAPhotoMaps connects to TerraServer-USA and downloads the map data for that area.
Instead of scrolling, you can also go directly to a location that you know the coordinates of. Just choose the Go To Lat/Lon item in the View menu and enter the coordinates.
USAPhotoMaps has two display modes: aerial photo and topographic map.
When you download data to fill in the gray squares, only data for the particular
mode that you’re in is downloaded.

Switching between aerial photos and topographic maps

After you know where you are in a photo, look at the commands that you can use to move around. As I mention earlier, TerraServer-USA provides both aerial photos and USGS topographic maps,and USAPhotoMaps lets you switch between the two types of images. (Figure above shows a topographic map.) This is useful because you can look at a topographic map and then immediately see what the same location looks like as an aerial photo. This is a big advantage because aerial photos often show more feature detail than topographic maps.
Here are the two ways (in USAPhotoMaps) to display a topographic map version of an aerial photo you’re viewing:

• From the View menu, choose Map Type➪Topo.
• Press the T key.
• If gray squares appear onscreen, you haven’t downloaded map data for that area yet. To download the map, press the F key. To switch back to an aerial photo view of the location
• From the View menu, choose Map Type➪Photo.
• Press the P key.