Selecting the appropriate altitude for your drone mapping mission is crucial for obtaining high-quality data that meets your research objectives. It sounds hard, but the good news is that it really doesn’t have to be.

Here’s how to determine the best altitude for your mission, what to do if you realize mid-flight that you’ve chosen the wrong altitude, and when it’s better to err on the side of caution by flying too high or too low.

Determining the best altitude for your mapping mission

To choose the optimal altitude for your drone mapping mission, follow these steps:

  1. Identify the smallest feature you need to detect: Determine the size of the smallest object or feature that you need to identify in your imagery. For example, if you’re studying vegetation health, you may need to detect individual plants or leaves.
  2. Calculate the required ground sample distance (GSD): GSD refers to the distance between the centers of adjacent pixels on the ground. To calculate the required GSD, divide the size of your smallest feature by 10. For instance, if your smallest feature is 20 cm, your required GSD would be 2 cm/pixel.
  3. Determine your drone’s camera specifications: Look up your drone’s camera specifications, including the sensor size, focal length, and image resolution.
  4. Use a GSD calculator or mission planning app: Input your required GSD and camera specifications into a GSD calculator or mission planning app to determine the appropriate altitude for your mission. Many apps, such as DJI GS Pro and Pix4D Capture, will automatically calculate the optimal altitude based on your desired GSD and camera setup.

Realizing you’ve chosen the wrong altitude mid-flight

If you find yourself partway through a mapping mission and realize that you’ve chosen the wrong altitude, don’t panic. Here’s what you should do:

  1. Assess the situation: Quickly evaluate whether your current altitude is too high or too low based on the quality of the images you’re capturing.
  2. Decide whether to continue or abort the mission: If you’re flying too high and the image quality is insufficient for your research needs, it may be best to abort the mission and start over at a lower altitude. However, if you’re flying too low and still capturing usable data, you may choose to continue the mission to avoid wasting time and battery life.
  3. Adjust your altitude if continuing: If you decide to continue the mission, carefully adjust your altitude to the optimal level based on your reassessment. Be mindful of any obstacles or terrain changes that may affect your ability to maintain a consistent altitude.
  4. Plan for post-processing: If you complete the mission at a suboptimal altitude, be prepared to spend additional time in post-processing to correct any issues with image quality or alignment.

Is it better to fly too high or too low?

In general, it’s better to err on the side of caution by flying slightly higher than necessary rather than too low. Here’s why:

  1. Safety: Flying at a higher altitude provides a greater margin of safety, reducing the risk of colliding with obstacles or terrain.
  2. Legal compliance: Many jurisdictions have regulations regarding the maximum altitude at which drones can operate. By flying higher, you’re less likely to inadvertently violate these regulations.
  3. Easier post-processing: Images captured at a slightly higher altitude may have a lower resolution than desired, but they can often still be used for analysis with some additional post-processing. In contrast, images captured at too low an altitude may suffer from distortions, motion blur, or incomplete coverage, making them less usable.

However, there are some situations where flying lower may be preferable:

  1. High-detail requirements: If your research requires extremely high-resolution imagery, such as for detecting small insects or plant diseases, flying at a lower altitude may be necessary to achieve the desired level of detail.
  2. Limited battery life: Flying at a lower altitude can sometimes allow you to cover your mapping area more efficiently, reducing the number of flights needed and conserving battery life.
  3. Unique terrain or environmental conditions: In some cases, specific terrain features or environmental conditions may necessitate flying at a lower altitude to capture usable data. For example, if you’re mapping a narrow canyon or working in an area with heavy vegetation cover.

By understanding the factors that influence altitude selection and being prepared to adapt to changing circumstances, you can ensure the success of your drone mapping mission and obtain the high-quality data needed to advance your environmental research.

Need more tips and tricks? Check out our complete guide to planning and flying your drone mapping mission.