The Aerial Perspective Blog

Drone Flight Plan 101 for Photogrammetry

| Alex Wright | Leave a Comment

Why should you use a drone flight planning app for photogrammetry?

As UAV mapping grows in popularity, aspiring drone pilots are bound to hear about automated flight planning, flight control, and image capture apps. (We’ll call them flight apps for brevity.)

This is likely to be a new concept for first-time commercial pilots, and maybe even for businesses specializing in manual flight operations like photography or newsgathering. But a lot of the literature just assumes everyone knows what a flight app is and why it’s critical for photogrammetry. Read on if you missed the memo.

This isn’t going to be another of those “best apps for drone flying” lists, but an explanation of what flight apps are, how they work in the field, and why pilots absolutely need them for commercial UAV mapping.

What is a flight app?

A flight app is a computer program that lets you plan, execute, and monitor automated drone flights from your computer or mobile device. Many flight apps also allow you to configure photogrammetry mission settings such as camera angle and image overlap, further simplifying your job.

Since they exist on your PC, laptop, tablet, or smartphone, flight apps don’t typically come packaged with commercial-off-the-shelf drones. You’ll have to buy one separately and download it.

A drone, laptop, tablet, smartphone, and FPV headset
With a flight app, you run the mission from a laptop, tablet, or smartphone instead of your manual controller.

How do they work in the field?

No two flight apps are exactly alike. But here’s a hypothetical example of how you might use one to conduct an automated photogrammetry flight:

Preflight Planning

You arrive at the mission site with your drone and a tablet on which you’ve installed your flight app. When you boot up your tablet, the flight app displays a GPS map of the surrounding airspace. You draw directly on this map—either manually selecting waypoints for the drone to fly over or designating a coverage area and letting the app design a suitable flight pattern. Then you open other menus to set your drone camera angle, the number of photos it should take, and the amount of overlap between adjacent photos.

Flight

With everything set, you tap a button on the tablet and the drone takes off on its own towards the mission area. At this point, you probably put down your tablet and pick up your drone’s control stick if only to assume manual control in an emergency. Ideally, the drone follows its preprogrammed flight pattern, takes the necessary photos, and lands without your intervention.

Post-Flight

With your drone safely on the ground, the flight app begins automatically downloading photos from your drone’s SD card to your tablet and may even kick off an image processing job.

Why are they critical for UAV mapping?

Flight apps make professional UAV mappers more effective at their jobs. Here are a few reasons why you need them:

Precision

While a skilled pilot can achieve a lot, it’s very hard to do professional photogrammetry under manual flight control. Clients expect lifelike 3D models. But most photogrammetry software is unforgiving to variances in photo resolution caused by even slight changes in a drone’s airspeed, altitude, and pitch. Furthermore, most photogrammetry missions call for taking photos with a precise front and side overlap (70%, for instance). This is virtually impossible for a human to achieve with consistency. But computers do it effortlessly.

Efficiency

A good flight app not only executes missions with inhuman precision, but also with inhuman efficiency. The first time you use a flight app, it may shock you to see how quickly it completes the mission. With modern drone batteries lasting no more than 30 minutes, automating the flight can save you valuable time and let you cover much larger areas.

Reduced Pilot/Observer Workloads

If you want to run a single-pilot UAV mapping business, flight apps are essential. Anyone who has tried conducting a manual photogrammetry flight solo knows they risk breaking Part 107 regulations every time they glance momentarily from their drone to their camera to line up a shot. More importantly, the danger of actually losing visual line-of-sight increases with the size of the mission area. (You’d think by now that all drone manufacturers would paint their airframes bright orange for visibility, but for some reason they love gray.)

By using a flight app, you can look directly at your drone throughout the flight while the app handles the camera work. This means you can conceivably photograph large-scale areas safely without having to hire a visual observer.

All-In-One UAV Mapping Tool

Think about the complex workflow you must follow to conduct a single photogrammetry flight. First, you need to check an app like NOTAM Search or B4UFly for flight restrictions. After each flight, you need to manually transfer your photos from your drone to your smartphone or PC, and then from there to a desktop or cloud-based photogrammetry provider.

A good flight app is like a Swiss army knife for photogrammetry, handling automated flight planning, restricted airspace awareness, data capture, and maybe even image processing all in one application.

A drone transfers its image data to a laptop and then to the cloud for processing
After a flight, some apps may automatically transfer your images for photogrammetry processing.

Is all UAV mapping automated?

In general, manual piloting skills still matter in UAV mapping. Most flight apps build what pilots refer to as “lawnmower” flight paths, sweeping back and forth over the target area at a relatively consistent altitude and maintaining a fixed camera angle. While this is great for capturing flat, multi-acre sites, it doesn’t give the drone a clear view of vertical structures. Using a flight app over a forest might result in a 3D model of trees with clear canopies but blurry, distorted trunks. To get around this, pilots may still supplement their automated flights with manual flights—letting the app survey the entire area from above, and then conducting manual flights that orbit tall structures to capture their side views or even fly underneath their overhanging surfaces.

That said, some companies have begun offering flight apps designed specifically for vertical structures, and they are likely to become more commonplace as the tech evolves.

How to choose your UAV mapping flight app?

There are many flight apps on the market, but they aren’t all necessarily suited to every UAV mapping mission. If you decide to purchase a flight app for your business, review these common but important features:

Drone Compatibility

Before choosing a flight app, make sure your drone is compatible. Some drones, especially new models, may not support all available apps. For example, the DJI Mini 2 was released in November 2020, but its users had to wait for a January 2022 firmware update before they could use any automated flight app. As of this writing, many app developers are still playing catch-up.

Waypoint Flight Planning

This is a core feature of flight apps, but it’s worth mentioning. Your app should have an intuitive map that lets you draw the target area using lines, points, and polygons, and monitor the drone’s real-time position during the flight.

Camera/Overlap Control

Flight apps tailored for UAV mapping also let you configure camera settings like angle, shutter speed, and ISO, as well as the overlap between photos.

Flight Restriction Overlays

This important safety feature lets you see TFRs and other no-fly zones on the map as you plan your flight and may even prevent you from plotting waypoints in illegal airspace.

Integration with Photogrammetry Software

The best flight apps are part of a larger UAV mapping suite and can save you time by automatically transferring your images from the drone’s SD card to your mobile device and from there to your photogrammetry engine for processing.

Optional: Vertical Structures

As stated above, most UAV mappers can supplement their automated flights with manual flights to capture the occasional tower, tree, and building. But if a significant part of your business is modeling vertical structures, it might be worth finding an app that offers more than the standard “lawnmower” flight paths. Be aware that you may have to pay a steeper price.

Final thoughts

We hope this post has demystified the concept of flight apps and convinced you of their value in UAV mapping/photogrammetry. Let us know if we’ve missed any important app features. Most of all, fly safely.


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