Share | 03/16/2020
Sometimes creating a high-quality map can be a challenge, but it doesn’t have to be. We will walk through a simple process to plan a mission, capture data, and create quality data products.
For this example, we’ll assume we are mapping a mid-sized site and creating three standard data products: orthomosaic, digital surface model, and contour map. We’ll refer to Measure Ground Control (MGC), an end-to-end software solution powered by Pix4D, along the way.
Now let’s get started.
Data quality begins with a plan. It is imperative that you fully understand the job location and what kind of data you need to collect. That information will drive decisions on pilots, equipment, and flight settings, just to name a few. Here are some things you definitely want to plan around:
Measure Ground Control offers comprehensive program management and mission planning tools. Create a new mission, check airspace, assign resources and manage your program calendar.
Since you have a good understanding of the site and data requirements, you can create your flight path in advance. When you plan to create a map, you will typically collect data using an automated grid flight pattern. Using an automated flight path will ensure that images are captured in a consistent manner and with proper overlap. With the right settings, you will get a much better map.
Grid flight screen in the MGC flight app
A Word About Overlap: You will want to set your grid flight with a minimum 60% overlap. However, the type of site matters. The more homogenous your site is (like a forest of trees or grassy field), the higher your overlap needs to be, often up to 85% or 90%. Mapping software uses tie-in points – unique visual cues – to stitch images together into a map. If all your images look the same, it’s much harder to put them together, so more overlap is required. Think of it a bit like putting together a puzzle – if every piece looks the same, it’s harder to assemble, so you need more cues.
Other recommended flight parameters include altitude of 200-300ft, speed of 11-12mph (note, if using MGC, it will auto-set the best speed for your flight plan), and camera angle of 90 degrees for 2D mapping.
If you are using Measure Ground Control, you can create automated grid flight paths in either the web portal or the flight app. When using the web portal, flight plans will automatically sync to the MGC flight app for the pilot in the field.
Since you’ve already created an automated grid flight path, flying and collecting data is simple. Start by completing a pre-flight checklist in the MGC flight app to keep organized in the field and ensure that proper protocol is followed. Confirm weather and airspace conditions and, if needed, get real-time authorization through LAANC (for flying near participating airports).
Now just make sure your take off (and landing) location is level and free of obstructions, make any last adjustments, and start your flight. Your drone will automatically collect data according to your flight path and parameters. Maintain visual contact with your drone and ensure that it progresses through each segment of your grid flight as planned.
If you need to re-fly a portion of your grid for any reason, the MGC flight app makes it easy. No need to re-do the entire flight path from the beginning.
Flight log data in the MGC web portal
Your completed flight creates a flight log that combines your checklist, equipment, and location information with telemetry data like pitch, yaw, roll, altitude, and speed. As a professional drone operator, you will want to capture every flight log for tracking and compliance.
With the MGC flight app, detailed flight logs are automatically uploaded to the MGC web platform via a secure cloud storage system run off US-based servers. Logs can also be added with DJI Log Sync or manually.
Confirming images for processing in MGC
After data collection, you will upload your images for processing. Always review your data before processing to confirm the quality and completeness of your data set. Make sure your images are crisp and that no areas were missed, and that there are no stray pictures that don’t belong in your map. Remember, bad data in equals bad data out, so it’s important that you create your map using a complete set of quality images.
In MGC, upload your raw data to the mission page, where all mission-related information is kept in one place. You will have the opportunity to review each image along with its capture location. Confirm data quality and exclude any images that don’t belong prior to processing.
Once you are happy with your raw data set, you will proceed with processing your images. The steps required will depend on the software you are using. Some software can be tricky and require software-specific training and/or a background in GIS data analysis. Other software, such as Measure Ground Control, use optimized settings and allow you to process data at the push of a button. Processing time varies anywhere from an hour for small maps to more than 24 hours for very large maps in excess of 1500 images.
With MGC, images are processed and data products are created through a seamless integration with Pix4D, the industry leader in photogrammetry.
Once processing is complete, you have access to your data products. For this example, we’ve chosen the three standard data products produced by Measure Ground Control:
Depending on the software you are using, you may view your maps, take measurements, or export files for use in other GIS software platforms.
Ground Control’s map viewer is an advanced platform for viewing your data products in 2D. You can take basic measurements, turn data products on and off, import your own 2D layer, and add information like the flight path.
Sign up to receive updates directly to your inbox.
