Drone Project Assessment

The Power of Analytics

We are committed to safe operation of construction equipment be it a crane or drone.  The following illustrations demonstrate our continuous commitment to safety which occur prior to every flight; Airspace, weather, FAA approval, Job Safety Analysis (JSAs).  We are professionals who understand the rules and regulations of our industry.  Let’s talk!

We regularly review and communicate with Federal, State, and Local agencies to understand currency as well as compliancy to the standards.

Our Drone Tech

Yuneec 520E RTK

E90X Camera

Emlid Reach RS2 receiver

GNSS antenna

Pix4D 

Our process is a

Differentiator

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Global Navigation Satellite System (GNSS) receivers measure time it takes for a signal to travel from a satellite to the receiver. Traditional GNSS receivers, like the one in a smartphone, determine the position within 2-4 meters (7-13 ft) accuracy. The limited accuracy is due to GNSS signals being “Perturbed”.  RTK and PPK technologies apply corrections to the GNSS signal data to provide a greater degree of location and height accuracy.

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Global Navigation Satellite System (GNSS) receivers measure time it takes for a signal to travel from a satellite to the receiver. 

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To perform an accurate RTK survey, you need a rover (the drone) and a base (the base station) that transmits the corrections in real-time.  The base's mission is to stay in one place and send corrections to a moving receiver. Rover uses that data to achieve centimeter precise position.

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An alternate method is the Networked Transport of RTCM via Internet Protocol or NTRIP network which allows your rover to accept corrections over the Internet with no need for the second local receiver acting as a base…WE use both systems!! 

 

 

We then employ photogrammetry using a camera  mounted on the bottom of our UAV/drone and the camera takes numerous overlapping photographs of each area in question. 

 

 

With this information and positions identified on two or more photos, software generates 2D and 3D images in real locations for construction planning, execution, survey, and handover to our clients.

Flight operation

Improved RTK Drone Accuracy

  • Consider the weather - Strive to fly while the sun is highest in the sky and avoid weather patterns such as high winds and cloud cover. Flying when the sky is overcast allows you use the clouds as a giant light diffuser. Light diffusers are common in professional photography because they provide soft, even lighting on your subject. This can greatly reduce shadows, blurriness, and glare from reflective surfaces all of which will improve the quality of your map. This technique is most effective for 3D models.

  • Use a high-resolution camera - What exactly does resolution have to do with map accuracy? Put simply, increasing the resolution of an image decreases its ground sampling distance (GSD), or in other words, it reduces the space between individual pixels in an image. 

  • Fly at a lower altitude - Flying at a lower altitude serves two purposes. It captures more details in the landscape and therefore more data points to work with. Low altitude flights also result in a greater number of overall images, again increasing the probability of matching more common points on a map.  

  • Use a higher overlap - Increasing the overlap for a flight is another way to create more matched points and greater accuracy. Overlap refers to the percentage of both side lap and front lap. Side lap is the percentage of overlap between each leg of a flight, while front lap refers to the percentage of overlap between one image and the next and is  balance between accuracy and large image quantity. 

  • Use a mechanical shutter camera - any out-of-the-box drone cameras use a rolling shutter. This means that the camera records each frame line-by-line from top to bottom. When taking videos or photographs, this helps reduce motion blur. However, it can also sometimes cause what’s known as “rolling shutter effect,” where surfaces in a photograph appear warped because the camera-object relation changed before the full image was recorded. An image that is warped in this way makes it difficult for drone mapping software to match points on a map, which as we talked about above, negatively affects the map’s accuracy.  

  • Capture ground control points - Some projects only need a high degree of relative accuracy, meaning a given point on the map is accurate relative to other points within the same map. For other projects — like geo-referenced overlays, design documents and land title surveys — it’s important to also have a high degree of confidence that the latitudinal, longitudinal and elevation measurements of a map are accurate. This is known as global accuracy. or projects that need this additional level of global accuracy, it is important to take additional steps to place the map within the fixed coordinate system of the real world. One way to do this is by using ground control points (GCPs.) Using GCPs essentially entails creating a series of ground markers in your area of interest prior to your flight and then manually recording the GPS coordinates for those markers.  You can radically improve your Absolute (or Global) GPS accuracy by using Ground Control Points (GCPs) and Checkpoints or Differential GPS systems (RTK, PPK, etc.). More on this below, but these can increase your Absolute accuracy to maximum of around 2-5cm horizontally, and 4-8cm vertically.  

  • Operate a drone with RTK GPS system 

  • Operate at a slower flight speed