True Orthophoto of UofC

Being that an orthophoto is a fully corrected image, which means you can use it for a map. Essentially, anything you can use a map for, you can use an orthophoto as well. This is a large variety of potential applications. Municipal and state governments may use them as basemaps. Engineering companies may use them for project planning pipeline installation. It may even be used for city planning. Essentially, as with a map, it has a huge variation of engineering or non engineering projects. Now you may be thinking, why not use a traditional vector map? The orthophoto holds a few distinct advantages. For many areas, an orthophoto can be cheaper to produce than a traditional vector map and is also generally more encompassing in terms of what is presented in the photo. Additionally, it is useful for verifying vector datasets as it is geometrically accurate to the actual earth.

An orthophoto is the culmination of a lot of consecutive work that is eventually combined to create the desired digital image. Much of the work is dependent on the quality of the previous task package. Therefore, it is important to guarantee precision periodically throughout the design process. The first step was surveying ground control. The quality of the ground control was validated by comparing surveyed Alberta Survey Control Monument coordinates to their published ones. This precision would be propagated throughout the work, so it was important to ensure the ground control was accurate. The quality of the aerial triangulation could be confirmed more easily, through visual point checks and root mean square values. The quality of the final mosaic was assessed with a simple visual check, looking for misaligned seams or distortion in the image. Finally, the final orthophoto accuracy was validated by manually measuring the ground control in GlobalMapper and comparing it against the values from our survey, which have a known precision.

In terms of cost, the team was able to achieve a final product without spending a single dollar. The equipment for the ground control survey was all rented courtesy of the survey store on campus. A variety of software were used during the process, but all were accessible through remote access to OGL’s computers, giving the team free access to a variety of excellent photogrammetry software packages. The team did encounter a variety of challenges ranging from licensing issues to software crashing, but were able to overcome these obstacles with the help of advisors at OGL. Additional required software that could not be accessed through OGL were accessed using campus computers. The work itself was very challenging, and the team had to dedicate hundreds of combined hours in order to achieve a satisfactory final orthophoto. However, much of this time can be attributed to learning the ropes and gaining experience in all the work that goes into creating a true orthophoto, as many aspects of the design were unfamiliar to the team.

With a young team working on a project of this scale, much of the process is a learning experience as you go. There are always design choices that could be improved or modified to achieve an even better final product. Upon reflection, the team decided there were a few ways we could have gotten an even better orthophoto. The first would be a more dedicated ground control point survey. With longer setups times for a static survey, the accuracy of the ground control would have improved. This would have propagated the accuracy throughout the work, improving the accuracy of the final orthophoto. Additionally, the quality of the photo could have been enhanced by upgrading from just the digital surface model that was utilized. If the team could get access to building models for the campus and combine these with a digital elevation model, orthophoto distortion on the buildings could have been avoided.