Field Activity #5- Obliques for 3D Model Construction

    In our fifth field activity we carried out a mission using oblique imagery for 3D model construction. This is the first time that we have used oblique imagery in the field. In all of our other field activities we have used nadir imagery. Nadir imagery is when the camera is pointed directly at the ground. This will give us an direct overhead view of our area of interest. Oblique imagery is slightly different than nadir imagery. Oblique imagery is when part of the horizon is in the picture as well, typically close to a 45 degree angle allowing for a side view of the area you are trying to take images of. Oblique images are perfect for allowing us to see the side view of the AOI allowing for us to compute the images into creating a 3D imagery model.
    The study area for our fifth field activity was on the soccer fields like many of our previous field activities. We took oblique images of the shed at the soccer fields using both the Iris and Gem platforms. It was a perfect day for flying with no clouds and barely any wind that made the flag move.

    In this field activity we used two different platforms. For our first mission we used the Iris platform with a GoPro camera mounted on it. The GoPro camera doesn't have GPS attached to it, so we would have to use GCP's while transferring and tying down our data when making a map of the shed. While using the Iris platform we used the structure scan mode in mission planner on the tablet. This allowed for us to set our parameters for the mission. We set the mission to oblique images and started the picture taking at 15 meters with 4 meter intervals. What I mean by this is that the mission was conducted in a cork screw fashion as it flew around the outside of shed it would raise 4 meters every time around. The images went up to 26 meters high and the images were taken at an 2 second camera photo interval. After the platform reached the 26 meter mark, it would then use cross hatching to get every nook in the roof. Upon completing this mission, we broke out the Gem platform. We did not use a mission planner for this platform, but instead flew this one manually. This allowed for us to start at a lower height and adjust the oblique angle for gain better detail on the lower section of the building along with the roof. We switched off flying around the building so everyone would get the opportunity to take pictures along with flying a multi rotor platform. 

    We have not yet learned how to process this imagery as this will be covered in future labs as the weather turns cold. When thinking about the difference between oblique and nadir imagery and the different purposes, I feel that oblique imagery has more of an upside then nadir especially with this field activity. With constructing a 3D model of a building this can pose many benefits compared to just having an overhead view like nadir imagery. This field activity was the first time that we used oblique imagery, but I look forward to seeing the differences once we have processed this imagery compared to using nadir imagery.