Change Detection Using Statewide Data

posted: April 23, 2013 | author: Woolpert Labs

Provided by guest blogger, Daniel Ngoroi, Woolpert subject matter expert, Dayton

A number of states have established airborne imagery and LiDAR acquisition programs that span multiple years. Ohio, for example, has an acquisition frequency of 3 to 5 years for new imagery and/or LiDAR. These programs provide many benefits to state and local agencies, including access to timely and high-resolution data.  In addition, these agencies can begin to take advantage of the multi-temporal nature of the data that only used to be available through satellite-based data inventories.

Change detection analysis encompasses a broad range of methods used to identify, describe and quantify differences between datasets of the same scene at different times. The change detection analysis can be used to track land cover and land use changes, building structure changes and urban sprawl, among other things. Woolpert has applied its automated change detection routines to assist jurisdictions in Ohio to carry out faster and more equitable property appraisals. This was accomplished by analyzing LiDAR and imagery from two epochs five years apart. Woolpert’s approach was able to ingest large amounts of data and output a change probability heat map. The heat map highlighted areas within the county that required further investigation. Woolpert provided a cost-effective alternative to an appraisal technique that used to involve boots on the ground—a process that was painstakingly slow and tedious.