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What a Surveyor Needs to Know to Start Mapping by Drone: The Deliverables

Daniel Katz - daniel@aerotas.com

This is the second in a series of blog posts expanding on our article in the Summer 2016 issue of California Surveyor magazine — download the magazine here, and find our article on page 37.

In the previous post we looked into the basics of the survey drone technology stack. In this post, we will dig in to the second topic that a surveyor needs to understand before deciding whether to start using a drone for aerial mapping: the deliverables that survey drone technology creates. As we discussed in the Cal Surveyor article, mapping drones can produce three primary deliverables: orthophotos, 3D models, and high-resolution photo and video. In order to use an aerial mapping drone profitably, a surveyor has to understand each of these deliverables and how a surveyor drone can be used to create them.


Survey Drones Easily Produce Orthophotos

An orthophoto is the easiest deliverable a mapping UAV can produce. Surveyor drones programmed to operate with autopilot, such as in the Aerotas Map Package, autonomously fly a back-and-forth pattern over a plot of land and capture overlapping photos. The post-processing software uses photogrammetry to stitch the individual photos together into a orthomosaic, resulting in the final orthophoto. The photogrammetry drone software then uses the GPS information tagged in the photos by the drone to georeference the orthophoto. Incorporating ground control points into the process can bring the absolute accuracy of an orthophoto to a tenth of a foot.

Orthophotos are valuable for surveyors in a number of ways. Many surveyors are already in the habit of putting Google Earth imagery behind their line drawings in order to help their clients and stakeholders understand what the lines mean in real life. However, Google Earth imagery is out of date, low resolution, and inaccurate — a UAV orthomosaic photo captured on the day a survey was completed is thus significantly more helpful to clients. Drone orthophotos are also accurate and high-resolution enough to allow surveyors to conduct 2D planimetric line-work, making jobs such as ALTA surveys significantly more efficient. In addition to these deliverable uses, a drone aerial orthophoto is a record of a site from the day it was surveyed. If a crew misses or mislabels a shot, or if there is a disagreement among stakeholders about the state of construction on a site, the orthomosaic photo is invaluable.

Considering how simple it is to complete a drone mission that produces an orthophoto, it is easy to understand why many surveyors have gotten in the habit of bringing an aerial survey drone on every job and automatically collecting an orthophoto as part of their work.


Drone 3D Surface Models Enable Topographic Mapping

The same drone operation that can produce an orthophoto can also produce a three-dimensional digital surface model of a site. Since the drone automatically captures every point on the ground in several photos, the photogrammetry software is able to construct a 3D model of the surface. The software processes the model as a point cloud. It can then use this point cloud to produce a TIN file of the surface of the point cloud model.

The 3D modeling capabilities of survey UAVs is a huge opportunity for many surveyors. This ability of a mapping UAV means that the field work for a topographic mapping job can be reduced to just setting five ground control points and conducting a a 15-minute drone aerial survey. The resulting 3D model is reliably accurate to 0.1 foot horizontally, and 0.4 feet vertically. This means that from this one model, a surveyor can produce one-foot contour lines as well as 2D horizontal planimetric features, in substantially less time than by conventional methods.

Before starting a topographic mapping drone operation, it is important to understand that using a surface model to produce line work involves additional challenges. First, the 3D outputs from the drone photogrammetry software are very large file sizes, and the software to manipulate them is very powerful, so some surveyors may need to purchase a higher-power computer. Second, the process of going from 3D surface model or point cloud to contours, breaklines, and planimetrics requires specialized software and substantial know-how. Because of these challenges, our recommendation is to start with the operation and deliverable that is easiest to produce and produces value. Since many surveyors can easily manage and create value with an orthophoto, we recommend starting there and building to 3D capabilities once proficient with the drone operation.


Surveyor UAVs Can Capture Photo & Video

The first thing many people think of when considering a drone is its ability to produce beautiful high-resolution individual photos and videos from stunning new perspectives. This capability opens up additional opportunities for surveyors. Many firms use a drone to produce marketing materials, highlighting projects with beautiful aerial imagery and video. These photos and videos can also serve as client-pleasing bonuses at the end of a project. Additionally, these survey UAV capabilities can be used to keep track of progress at a site over time, and collect a record of a job site at key points in time.

Counterintuitive though it may seem, collecting individual photos and videos by drone actually requires a greater level of skill and experience than using the drone for aerial mapping. Photo and video jobs require being able to operate the drone manually, while for mapping jobs the drone is able to operate completely autonomously. Beyond this, producing good quality photo and video certainly requires artistic talent.


To Create Value With a Drone, Start Simply

A mapping drone can provide highly valuable deliverables for surveyors. In our experience, the most successful firms start their mapping drone program by focusing on the mission and deliverable type that creates value and is easiest to accomplish. The Aerotas Mapping System was designed for success. It includes everything a surveyor needs to start producing valuable mapping deliverables by drone as efficiently and cost-effectively as possible.

Learn more about the Aerotas Mapping System here, or contact us with questions at info@aerotas.com.

 

Daniel is Cofounder and Head of Strategy of Aerotas. He has a rich background in strategy and innovation consulting, helping businesses from startups to the Fortune 500 identify opportunities for innovation. Daniel is passionate about helping organizations see and incorporate new ideas into their business operations.