Our featured project of the week takes us to a small neighborhood in Cannon Beach where Jon Ellinger, owner of TLT Photography in collaboration with PLS Mike Magyar of Magyar Surveying captured this small neighborhood for a viewshed analysis of the nearby Pacific Ocean beach and breakers.https://sketchfab.com/models/ad20f180837144e29d238b1de376fa72
This is the story of the project in Jon’s words:
_ "The Backstory: _
A neighbor of our client needed to raise their roof to meet proper city building code but our client was worried that the raised roof would obstruct much of their view of the ocean breakers to the west. The alternative was to tear down the existing neighbor’s building and rebuild it according to new city planning rules which allowed for an even taller roof but slightly relocated from the buildings current location at the back of the lot. This presented an ideal situation to use a survey-grade 3D model created from aerial imagery with Pix4Dmapper software to conduct a legit viewshed analysis as viewed from the deck of our client’s property. Ultimately, our job was to not only qualify with imagery but also quantify with numbers the varying levels of obstruction from each possible scenario.
_ The Acquisition: _
Mike and I had sketched out 16 painted air targets for the project which he wasted no time surveying while I prepped the drone and checked camera settings and flight plans. About an hour and a half and 1400+ photos later we were packing up and on our way for a seafood snack at the Ecola Seafoods Market. The acquisition had gone wonderfully. There was an early morning layer of fog which prevented deep shadows and I was able to capture plenty of imagery with a ton of overlap for the model before the sun came out.
_ The Processing: _
Over the next week, I ran the data set through Pix4Dmapper both on my desktop and in the cloud as a backup at max settings to ensure I would have the highest resolution point cloud possible for the viewshed analysis. I had acquired just about 5 acres of imagery, capturing the entire length of Orford Street down to and on to the beach. I had flown at about 80ft and my average pixel resolution of the final orthomosaic was about 0.72cm/0.26in. I had used 10 of the aerial targets spread uniformly about the project AOI for georeferencing and set another 6 aside for accuracy assessment afterward. After processing overnight and light cleaning of noise from the point cloud I came out with roughly half an inch accuracy in the horizontal plane and about 2/3 of an inch in Z for vertical accuracy. This was an incredibly accurate 3D model for an entire neighborhood! The point cloud was 5gb and over 167 million points.
_ The Analysis: _
The analysis of the data was conducted within a CAD software environment. I created multiple models including the existing building, erasing the building, and putting in a new, up-to-city-code building. I then used the point cloud I exported from Pix4Dmapper to look at the view in the model towards the ocean from the left, middle, and right side of our client’s deck. From there I exported data into a professional photo editing software and did a pixel count analysis to quantify the percentage of view obstructed in each scenario. I’m not going to go into details about my proprietary methodology as I hope to use the same steps for future clients along the Oregon Coast where ocean views are held most sacred!
As a professional photogrammetrist, I have used a wide variety of software suites throughout my career. For my business, I choose to use Pix4Dmapper as it is the only cost-effective software for my small business that produces sub-cm resolution mosaics, achieves the highest absolute accuracy standards, easily works with local coordinate systems for construction sites, and has superior customer support for my more challenging projects."
Explore the project and feel free to share your comments and your own projects.