American Institute of Certified Planners (AICP) Practice Exam

What is a USGS orthophoto?

1. An aerial photograph altered to remove lens distortions

2. A digital map created using satellite imagery

3. A topographic map showing detailed contour lines

4. A type of historical photograph for archival purposes

The correct answer is: An aerial photograph altered to remove lens distortions

An orthophoto, specifically a USGS orthophoto, is an aerial photograph that has been geometrically corrected (orthorectified) to ensure that the scale of the photograph is uniform throughout. This means it has been adjusted to remove lens distortions, variations in perspective, and differences in terrain elevation. As a result, an orthophoto can be used as a reliable map substitute, where distances and areas can be measured directly from the image with accuracy. This process of orthorectification allows for the integration of the aerial images with other geographic information system (GIS) data. As a visual representation reflecting true ground locations, USGS orthophotos serve various practical purposes, including urban planning, environmental studies, and land use analysis. Other options do not accurately define what an orthophoto entails, focusing instead on different aspects of geographic representation without the critical element of correcting for distortion.