The Davis Building- Detailed Building Envelope Aerial Imaging

The Davis Building is a unique building full of history located in the heart of downtown Dallas, Texas. The property was acquired by a Dallas oilman named Tim Headdington and is currently under renovation to convert the 183 apartment lofts into 213 luxury rentals. The Davis building was originally constructed back in 1926 and was converted to apartments back in 2003. Many developers have taken these old vacant buildings and made them into high end hotels, office buildings and apartments.

When taking on major renovation projects like this, one of the major undertakings that some folks may not even think about is waterproofing the facade. Identifying leaks and making them stop is no easy undertaking. The last think you want to happen is have your newly renovated interior destroyed by water from a leaky facade. Leaks can come from minor defects or damaged areas and cause major problems.
The property owner and Mycon General Contractors asked us to deploy drones to effectively document the present condition of the entire building envelope and deliver the images for detailed review and analysis. They are looking to identify where all the sub centimeter imperfections and openings exist on the facade and map out a plan to perform proper repairs to eliminate existing leaks and problems. This idea was much easier said than done!

The Challenges

There are many concerns when flying drones downtown, these are the challenges we had to research and learn to overcome before we could commit to completing this project efficiently, effectively and most importantly, safely:
  • Downtown Dallas is very close in proximity to a major air field, Dallas Love Field. Our first obstacle was obtaining flight authorization from the FAA to legally operate in this location. We were able to get clearance to fly 100′ above the structure we were inspecting.

 

  • The way most drone satellite networks are setup, you need good clear visibility to the sky from multiple different directions for your drones to properly connect to enough satellites to get an accurate GPS fix. DJI drones do not function normally without a good satellite fix. You can run them without satellites, but achieving good stability and efficient work flow to get good clear visibility is not possible because you have to counter the external elements that move the drone around unpredictably. During most of this project, we did not have good satellite connection. This meant we had to be highly attentive to the drones movements and reactions while trying to focus on getting good clear images.

 

  • In tangent with worrying about satellite connection is dealing with the unpredictable tunneling gusts of winds that come howling through the tall buildings downtown. While it may seem like a relatively calm day out with forecasted winds around 5mph, downtown Dallas can end up throwing random gusts of wind around 20 plus mph that can easily catch you off guard.

 

  • Next is dealing with traffic and a constant flow of people walking the streets to maintain a safe flight operation. Fortunately, between the parking garage and existing scaffolding that allowed walking traffic to walk across the building underneath it, the alley way was the only section of the building we had to worry about. We worked with Mycon Construction to close the alley during the weekend to ensure we were not operating over people for the duration of the flight.

The Process and Equipment

Our job was to document the entire building envelopes present condition providing the ability to identify sub cm and hair line cracks around the entire building. We used multiple different drones to complete this task. Our first work horse of choice was the DJI Inspire 2 with an x5s camera affixed with a 50mm lense. This allowed us to capture our images from a safer distance from the building while allowing us to still capture the high level of detail required. This took care of roughly half the building. Our other drone of choice was a DJI Mavic 2 Pro with a cage we designed to protect the propellers in case of an incident. Both cameras had the ability to capture 20 megapixel high resolution images and provided the stability needed to obtain crystal clear photos. Each provided roughly 28 minute flight times and served a unique purpose.

We had to consistently fly the Mavic 2 about 5’ away from the building. We used this drone for the ally (east side) and for the garage side of the building and in the horse show, which did not allow for much room for flying. For obvious reasons, we had to be selective with the days we chose to fly as strong winds tunneling though a tight 15’ gap between the 2 buildings in the ally doesn’t leave much room for error. We also had to get this portion of the project done while we could close the ally to traffic, routine trash pickups and people walking through. This meant it had to be done on a weekend. There were multiple times, due to the drones inability to communicate clearly with the controller caused by the signal bouncing around off the buildings, that we had to stay highly attentive to ensure we didn’t experience a crash or create an unsafe work environment.
We broke down the building by side and captured images systematically to ensure we can keep track of where each image correlates with its location on the building. These images were highly zoomed in. If we were to just deliver the 4,000 some odd images without any direction, you would have no idea where the image would be referenced. To the left is an image giving you the idea of the clarity of the images to be able to review small issues throughout the building. From each side, we broke each face of the building down into separate sections. Starting from the bottom, we capture the close up images starting from 1 side of the building and going across, making sure we have a little overlap in each image so we don’t miss parts of the building. Once 1 row is complete, we move up to the next level and work across until you have made it to the top!

Post Processing & Organization

Once we completed the field work, its on to organization and post processing. Trying to organize 4,000 images can be much more time consuming than you think. To give you an idea, it took roughly 2x as long to organize everything than it did to capture it in the field.
  • Our first step is to stitch together the zoomed out aerial images to create an image of the entire side of the building since we were un able to capture the whole side of the building in 1 image.

 

 

 

 

  • Then we start reviewing images to make sure the resolution and clarity are good for detailed review.

 

 

 

  • Next, we have to organize the images and reference their location on the building. This process is not difficult if you capture everything in the field properly, but can be time consuming. We look at each individual image and mark it accordingly on the stitched image. The image to the left is an example of our deliverable showing where every image is referenced for that entire side of the building.

 

Final Deliverable

Our deliverable consisted of roughly 4000 images, organized and referenced accordingly, stitched images of each section of the building, oblique images and direct overhead images of the entire building. Everything was electronically delivered as we completed each side of the building. We invested roughly 32 hours in the field and about 50 hours organizing and touching up the images to make them useful. We were able to achieve a high enough resolution to identify the small cracks and imperfections in the facade that would allow for moisture intrusion over time. The property owner and construction teams are now able to formulate a detailed plan for how to attack performing repairs accordingly without spending days hanging off the building to determine what requires attention vs what looks good.
We love performing this kind of work! It provides a legitimate value and pushes us to be able to navigate tricky flight situations and sharpen our skills to continue providing our clients with the product they need and deserve while limiting risk as much as possible. Seeing these old buildings get transformed into functional and occupied structures again is a pretty cool experience. If you think this service can benefit you, give us a call, we would love to help you assess your needs and determine if this will provide value to your specific situation!
          
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