GPS for Dummies.pdf - Engineering Surveyor

Chapter 20: Overhead Image Web Sites321Changing image resolution in TerraServer-USAAfter you display an aerial photo or a map, you can change the resolution.Resolution, especially when dealing with aerial photos, is expressed in meters(about a yard for nonmetric types). An aerial photo with 1-meter resolutionmeans that you can see an object on the ground that’s one square meter insize. The smaller the resolution number, the more detail the image shows. Forexample, Figure 20-3 shows the Space Needle viewed at 1-meter resolution.Topographic maps can be displayed from 2 to 512 meters in resolution, andaerial photos can be shown from 1 to 512 meters. If there’s data for an urbanarea with high-resolution, color photos, you can go from .25 to 64 meters;.25 meters is enough detail to start seeing people on the street, as shown inFigure 20-4.A resolution scale is shown immediately below the compass, to the left of themap or aerial photo. To change the image resolution, you can either Click one of the bars between the plus and minus buttons. The farthestbar on the left provides the least amount of detail and largest area, andthe bar on the extreme right shows the greatest amount of detail and thesmallest area. Click the minus button or the plus button. This decreases or increasesresolution one step at a time, respectively.Figure 20-3:The SpaceNeedle, inthe center,viewed at1-meterresolution.