Major cities have relied on digital ortho photography as a basemap for many years now. GIS information depicting various man-made features like roads, buildings, rivers and more, are structured so that each can be overlaid on the orthophoto for even greater value.

Over time and with new development, digital ortho photos and some content of the GIS layers become outdated. There are many different ways to determine the changes so as not to totally remap the entire area. In many cases only the ortho photo needs to be re-created.

Specialized equipment, as in a softcopy workstation may be used to determine what has changed. ACA can view old and new at one time, and up-date the changes that are necessary. Another method is to perform image change analysis to pinpoint new residences, roads, drives and more.

As technology moves forward, we are sure that even more sophisticated tools will become available. LiDAR, for one, is on the verge of providing advanced change detection. LiDAR is also a valued tool to update contour files and digital terrain data. ACA uses many of these techniques to create the custom solutions for our clients' particular mapping needs.