Flexible Configurations for Image QA/QC in the Cloud
The traditional method of conducting QA/QC for an aerial imagery project includes loading data on hard drives, shipping the hard drives to all the stakeholders, waiting for manually compiled comments, making changes and then finalizing the imagery. It is a process that lends itself to duplication of effort, overlooked errors, and delays.
In the past few years, a number of states have undertaken aerial imagery projects that include performing QA/QC in the cloud. This approach makes it easier to distribute the data to everyone who needs access, receive comments in a timely manner and efficiently track corrections.
Kentucky is one of the states that has moved QA/QC to the cloud, using a solution called “VOICE”—Virtual On-line Inspection, Checking and Editing. Designed and developed by Photo Science, a Lexington, Ky.-based, geospatial mapping and solutions company, VOICE has been implemented in several statewide orthoimagery projects.
Kentucky has never had statewide leaf-off full color aerial imagery, but by the end of 2015, over 40,000 square miles of up-to-date imagery and DEMs will be available to the public. Kentucky awarded Photo Science with a digital orthoimagery and LiDAR contract on Dec. 22, 2011, for the collection of 1-foot resolution aerial imagery and LiDAR of the entire state. As areas are completed, data is processed and stood up through a Web service available to state government agencies and the public.
Kentucky is using a cloud configuration suitable for a client that already has mature computing and human resources. The state hosts the aerial imagery within its own server-based GIS while Photo Science hosts VOICE. The Kentucky Division of Geographic Information receives original imagery in batches of 0.5 to 1.0 terabyte on hard drives. Reviewers examine the data for image anomalies, such as a glare off a windshield, flares or smears; elevation anomalies where an elevated object is out of focus; and possible misalignments at seam lines. VOICE allows the reviewer to mark the issue, provide a written description, and send the comment to Photo Science data production staff in real time. For now, VOICE handles QA/QC for imagery only; however, a LiDAR tool is in development.
“VOICE is a very good tool for reviewing imagery because it allows us to distribute the workload to other state and local agencies that have the expertise to help, rather than trying to do all the work with our small staff or contracting to third parties,” said Kent Anness, Commonwealth of Kentucky, GIS Manager, Division of Geographic Information. “We have been extremely pleased with VOICE’s functionality and speed.”
The best cloud configuration for geospatial information depends on the client’s existing software, hardware and human resources. An important advantage of cloud computing is its flexibility. Data may be hosted by one or more client organizations, or by a third party, while the application is hosted and maintained elsewhere.
In North Carolina, which also uses the cloud to streamline the QA/QC process, a third-party vendor hosts the imagery during the QA/QC phase. Photo Science is hosting VOICE, and the state will host the final imagery on NC OneMap when it is made available to the public. Photo Science is one of four contractors supporting the North Carolina program, but the firm was selected to deploy its VOICE solution to support QC for the entire project. The North Carolina Center for Geographic Information and Analysis (CGIA) was motivated by the request of an important client, the 911 Board and Public Safety Answering Point (PSAP) offices, to find a more efficient methodology to evaluate initial delivery of the imagery with PSAP and local government participation. With new imagery being collected by four different aerial mapping vendors, and reviewers at the state level down to the PSAP offices, the cloud seemed like a good solution to make the process faster and more reliable.
“The 911 Board requested early review capabilities for this statewide project, so we had to look at the available technology and figure out a better way,” said Tim Johnson, CGIA director. “All initial QA used to be done by state employees and private firms, so the PSAP offices didn’t see anything until the end. Now they are an integral part of the process upfront.”
“Everyone also wants access to the final imagery as quickly as possible,” he added, “so this is a way we can better serve our constituents, including other government agencies, private businesses such as real estate and engineering firms, and other organizations and individuals that utilize our geospatial information.”
One year into the four-year project, 25 counties out of 100 are complete, and delivery of imagery is expected by mid-February. Due to the thorough review by all interested parties during the QA/QC phase, the final images are expected to be practically error-free and will be posted on NC OneMap this spring.
“VOICE is our first experience with the cloud, and it has been positive,” concluded Johnson. “We feel that cloud technology offers advantages to our organization, so we will probably pursue additional applications in other areas in the future.”