Drones for inspections

The Two Methods of Remote Inspections

Live Stream or 3D Model

Drones bring safety and efficiency to inspections of elevated surfaces and elements whether it is an electric transmission line, cell tower, or a flare stack at a refinery. Personnel do not have to directly access the various elements of these assets in order to visually assess their condition in the case of electro-optical (EO) sensors, or identify hot spots or cold spots using infrared (IR) sensors, which can then be used to identify defects within the material or operating unit. The fewer times you have to climb a cell tower, the fewer times you’ll be exposed to injury or death due to a fall. Shutting down a flare stack, impacting production capacity, and accessing the flare tip for an inspection is both costly and time consuming. Instead, it can be inspected with both EO and IR sensors to visually confirm the tip condition and see the combustion process and temperatures without having to hoist personnel up with a crane. The same applies to the inspection and condition assessment of roofs whether they are new, old, one story high, or on top of a high-rise building.

In a conventional inspection scenario, a subject matter expert, either an engineer or specialist, would have to go to the field to conduct these inspections and condition assessments. This of course costs time and money for travel and lodging, in addition to the inspector’s lost time on other projects. While in the field, the inspector would have to take pictures and index them in a photo/video log and provide notes on what issues or defects they had found. This is time consuming and daunting, particularly if several hundred images are needed to be collected and reviewed. Back at the office, the field findings would then be collated into a report of findings and possible fixes.

With the first level of inspections facilitated or augmented by a drone, the expert was usually on site standing next to the pilot observing the video stream from the drone. This had the added benefit of the expert being able to communicate directly with the pilot, position the drone, and take imagery of any areas of interest. This method also had the added benefit of reducing the duration of the inspection since rope access and other techniques were not needed to view the areas of interest. The downside of cost of time and money for travel and lost productivity on other projects still exists, though not as much with the reduction of the duration of the inspection.

In the next level of inspections via drones, the expert does not have to be on site at all. This greatly reduces travel costs and increases the efficiency of high-cost engineers and consultants. This is done by transmitting the drone data straight to the desktop of the expert, eliminating travel expenses and maximizing the utilization rate of the expert by allowing them to direct and inspect multiple remote projects, increasing productive and billable time.

This second level of drone inspection can be done by relying on two different methods or a hybrid of both. In the first method, the expert is in direct communication with the pilot, similar to the on-site method via an internet browser while observing the live video feed. This allows the expert to view the feed directly in real-time while directing the pilot to take additional high-resolution imagery or IR imagery for areas of interest. The deliverable to the expert, in this case, is the video along with a voice recording of their communications, and additional high-res imagery delivered electronically. From there, the expert can produce their findings and recommendations to their client or organization. The benefit of this method is the interaction between the pilot and expert to ensure all relative areas of interest are covered.

The second method involves photogrammetry and the production of a 3D model. In this case, a programmed flight is flown to cover the subject. High-resolution overlapping images are automatically taken. Using photogrammetry techniques, specialized software creates a 3D model that can be observed in a cloud-based browser and/or computer-based program. The inspection is not done directly in the 3D model — the model is instead used to locate the most relevant high-resolution image by pointing and clicking within the model. The relevant image and the adjacent images are then presented to the inspector. The inspector can zoom in and out of the image and make direct annotations. The software can then generate a report of all the annotations made for the asset presented with the relevant image for each. In this method, the hundreds of images taken can easily be indexed by the 3D model with areas of interest inspected and annotated. Areas of completed inspections can be color-coded to prevent duplicate inspections or missed inspections of critical elements of the asset.

Imagine having to review the same number of images in a flat file and keeping track of where you have been/where you needed to go. The benefit of this method is the ability to locate, track and annotate a large number of high-resolution images and generate a report of all the annotations and their associated imagery.

A hybrid of both the live stream and 3D model methods provides the best results for drone inspections. You get the benefit of the expert’s input to identify areas of interest along with the 3D model’s method of organising, visualizing, and report generating capabilities. In this hybrid method, the expert views the video feed of the automated flight from the desktop. When they see areas of interest that need further investigation and imagery, they can have the pilot pause the automated flight and maneuver the drone to a position best to capture the elements of interest. Once this is complete, the programmed flight can be resumed by automatically picking back up where it left off. In this way, the hybrid method maximizes the return on the drone-based asset inspection.

Drone inspections, by their very nature, are safer and more efficient than conventional on-site expert inspections. To put it simply, they save both time and money. As drone inspection technology allows for more robust inspections, the result will be a reduction in risk and costs while increasing the utilization and billable hours of the expert inspector.

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