How to Take Better Solar Pictures With Your Drone

This is a guest post from Keith Perry, founder of Hudson Valley Drones. Keith is an instructor in the free course, “Solar + Drones: Managing Lighting, Exposure, and Glare in Your Imagery“. In a previous post, Keith offered up a Solar Company Guide to Drone Hardware.

Simply put, in order for us to obtain a good photogrammetry output, there must be a high quality input. In this article we are going to discuss some of the most important elements that contribute to high quality data collection, and how to conduct quality control and correct common issues that can impact your model.

All of this being said, while it’s important to remember that while we are flying a drone and take the necessary steps to conduct a safe and successful flight, it’s even more important to remember that broken down fundamentally, all that the drone serves as is a flying tripod to hold the camera that we are using to collect data. Therefore, it’s imperative that we at least have a high level understanding of how a camera works.

There’s often a debate as to whether someone should use AUTO camera settings vs MANUAL camera settings. We recommend that you try AUTO settings first, and then fine tune the settings manually if you’re unable to produce an acceptable result. A few red flags of unacceptable photographs would be blown out images, which means that they’re excessively bright. Excessively dark images have the same effect and can lose detail due to the lack of light. Blurry images are also bad and would require that adjustments be made.

There’s often a debate as to whether someone should use AUTO camera settings vs MANUAL camera settings. We recommend that you try AUTO settings first, and then fine tune the settings manually if you’re unable to produce an acceptable result. A few red flags of unacceptable photographs would be blown out images, which means that they’re excessively bright. Excessively dark images have the same effect and can lose detail due to the lack of light. Blurry images are also bad and would require that adjustments be made.

The exposure triangle is a visual representation of what elements that we can control with our camera settings. Aperture refers to an orifice that meters the amount of light that can be let into the camera, but can come at the sacrifice of depth of view. ISO refers to the sensitivity of the film or camera sensor, but adjustment can result in graininess or noise in your image. Finally, shutter speed refers to the amount of time your cameras shutter is open and the amount of light that is let through in that time. It can be adjusted, but can come at the expense of motion blur. We’ll go into these more over the next slides.

First, we’ll talk about shutter speed. Shutter speed refers to the amount of time that the camera shutter is open and exposing light to the image sensor. The longer that the shutter is open, the longer the light can shine on the sensor, and therefore the brighter the captured image will become. If you’re finding that your images are too bright or blown out, you can try increasing your shutter speed. This will limit the amount of light coming into the camera and darken the image. Similarly, if you’re experiencing images that are too dark, you can lengthen the shutter speed to let more light in. A word of caution– if as you decrease your shutter speed, you increase the likelihood that you’ll experience motion blur (notice the pinwheel image on the slide). If you experience this, you’ll have to increase the speed of your shutter and adjust another setting to get the desired result.

Aperture refers to the openness of an orifice in the cameras lens that is designed to meter light going into the camera. The wider that the orifice is open, the more light is let in. You can adjust this setting if you’re experiencing motion blur as discussed in the previous slide– instead of
slowing down the shutter, you can widen your aperture. Some drones, specifically the Mavic Pro, Mavic 2 Zoom, and some older models of the Phantom series do not have the ability to adjust the aperture. You can make up for this by adjusting other camera settings, or by using ND filters to meter the light going into the camera.

The last setting that we can adjust is the ISO, which adjusts the sensitivity of the film or sensor. We’d recommend trying to keep that as low as possible and to only adjust when you can’t fix your exposure issue by changing the shutter speed and aperture. The reason being is because the higher you set your ISO, the more likely you are to experience graininess and noise in your
imagery, and that can negatively impact the quality of your photogrammetry.

ND filters are basically sunglasses for your drone and allow for additional flexibility when using certain photo and video techniques. ND filters should be used in tandem with the other photo settings mentioned in this presentation. An important recommendation: ND filters come in different levels of quality. If you’re going to purchase them, we recommend purchasing ones directly from the manufacturer, or those that are of very high quality. This is a piece of equipment that you don’t want to skimp out on because your photography can suffer.

Bright colored siding and roofs can be particularly tricky to photography. A ways that you can improve your deliverables are to not photograph these types of properties on very bright and sunny days– instead try cloudy or overcast days. You can also try lowering your shutter speed and using ND filters to reduce the amount of light that is coming through into your camera.

One last tool that we’re going to discuss is the Histogram. A histogram provides a visual representation of the distribution of colors in your image. If you find that the graph is bunch up on the left or right sides, you might be experiencing imagery that is too dark or too bright. Aim for an even distribution throughout the graph which will be indicative of proper exposure and consistent brightness throughout your photos.

To review what we hope that you’ve taken away from this article:

1. Try using AUTO first.
2. Review your images onsite.
3. Make the appropriate adjustments and refly if needed.
4. Remove inconsistent images prior to uploading to Scanifly.
5. Practice, practice, practice– the more you use this material the easier the collection process will become.

NOTE: This presentation was adapted from the free course, “Solar + Drones: Managing Lighting, Exposure, and Glare in Your Imagery“