Purdue Wildlife Area Flights with a Mavic 2 Pro

 Introduction

Through Purdue's UAS program we were able to fly Mavic 2 Pros to do automated missions through Measure Ground Control to gather data of the Purdue wildlife area. This area is used for a variety of research in chemicals and controlled burns. The Automated flights lasted anywhere from 5 minutes to 15 which is plenty short for a Mavic's battery.  The first flight was over an older burn field and mainly to get used to the aircraft and measure ground control as well as laying out Ground Control Points (GCPs). The 4/14 flight was a two-part flight, The first one was over a new burn field and the second was a crosshatch over the construction site. The Crosshatch allows for the image generated to be 3D and allows for things like the volumetric analysis. The Last flight was one flight over the two previous areas that were flown the week before. This was to give an overall look at the field from the beginning to the end of all the flights.

4/7 Flight

This flight was a simple grid flight to take images of an area and to practice taking simple data and processing it into a map. This involved gathering the images, importing them into Pix4D and having it stitch it together, then taking the orthomosaic and running it through ArcGIS to process it into a map. 

Figure 1: Week 12s Map

4/14 Flight

This flight was a two-part flight the first flight we flew over a newly burned field which you can see in Figure 2. The second flight of this day was a crosshatch. This crosshatch allows for things to be distorted minimally when converting it into a 3d image. You can see this in Figure 3. Finally, with the crosshatch, we did a hillshade to bring out the 3d features more than with RGB images, this is visible in Figure 4.

Figure 2: The New burn fields

Figure 3: A RGB map of the Crosshatch

Figure 4: A hillshade of the crosshatch

4/21 Flight

This was the final flight of the flight ops that we did this month and it covered the entire 2 flight areas of the previous week. This was to be able to look at the difference between the 2 new burn fields and a week after, and the old burn field and how it looks now. For deliverables this week we had the full orthomosaic of the field and a comparison between the south burn field for all three weeks. We also compared the difference between phone GPS location and the aeropoint GCP tiles that we use. Figure 5 is of the burn comparison map and Figure 6 is of the GPS comparison.

Figure 5: The same burn field over 3 weeks

Figure 6: The GPS comparison

Conclusion

This series of flights allowed us to gather and process data from the ground up. We went out to the field and took the pictures, then processed them, and from there created maps from the data that we gathered. This was by far the most beneficial of the labs that we had to do as it builds on everything we learned and incorporated flight time and then the data processing that takes place after.

Using ArcGIS Pro

 Introduction

ArcGIS Pro is a data processing app that is a very powerful piece of software allowing you to layer your stitched images on top of a map and customize the map to fit that data. We covered ArcGIS a few times and this semester we used it for 3 labs. One was a recap following their online tutorials, the next is cartography fundamentals and finally, there was a volumetrics lab.

Figure 1: ArcGIS Pro icon

ArcPro Recap

The tutorial was on tourist locations in Singapore. This involved importing tourist locations for the area, removing excess information, and coloring the map so that it is easily readable. It also included a map tutorial to design a map at the end so that we had a finished product. The final product is visible in Figure 2.

Figure 2: Final Map from the Tutorial

Cartography Fundamentals

The next lab that was given was a cartography fundamentals lab which outlined the necessary components for a map. They were; a north arrow, scale bar, locator map, watermark, and data sources (like sensor, altitude, etc.). Within the lab, we were given DSM files (critical for hillshade) to use when looking at the hills and slope degrees, from there we were taught how to create a map from the image that we have taken and then how to add all of the fundamentals required. Here there are 2 figures, the first was of a hillshade, this is useful to look at volumetrics which will be covered in the next section. The second image compares the angles of the slopes and highlights them accordingly.

Figure 3: Hillshade

Figure 3: Shaded Slope

Volumetrics

The Final lab we had with ArcGIS was a volumetric analysis, which is simply in this case measuring a pile as the ground is dug up and as the dirt is hauled away. ArcGIS Pro also has the ability to highlight areas and tell the approximate volume, here in figure 4 is an RGB image with a DSM underneath used for the volume analysis. The highlighted areas around the 3 piles are the area that's measured.

Figure 4: RGB surface volume

The other volume calculation that ArcGIS Pro can do is take a series of volume measurements over time and then compare them in a final product. Figures 5-7 are the series photos that were used for the final product Figure 8.  Here the highlighted area of the 3 flights changes based on how much dirt was dug and then transported away. 

Figure 5: The first flight over the area

Figure 6: The second flight over the area

Figure 7: The final flight over the area

After these three flights were flown the final map can be made and finalized. This map compares the net gain, to the loss and also records the unchanged portion. Here the red is where there was a net gain and the blue is the net loss.

Figure 8: The final Volumetric Analysis

Conclusion

ArcGIS Pro is a powerful program that can do a lot given the right data. Their helpful online help forms guide you through the process of creating any map or dataset that you would need for work within the industry. Once again a drone is shown how much it can change the industry, as traditionally a person would have to take measurements all around a pile and then figure the volume. Now it is just as simple as a flight over a pile and a analysis to figure out the values.

Using Measure Ground Control

 Introduction

Measure Ground Control (MGC) is software that pairs with your drone and allows you to plan and carry out automated missions in a simple and safe way. It pairs with any DJI aircraft and allows for any and all missions one can plan. It also allows one to look into airspace maps of the area and ensure safety compliance for the flight, as well as allows you to edit all the little details of the flight to get the data just how you want it. Within the front page of the app you have 4 options; Airspace, settings, fly, and flight plan. Airspace as mentioned before allows you to check airspace around your area, settings allow you to change different things like maximum allowed flight altitude. Fly allows one to fly the aircraft just like they were in the traditional DJI app, and a flight plan is where you can plan and launch automated missions from.

Figure 1: The homepage of the App

Grid Missions

Grid missions are useful for taking many images over a large area like a field or building if you use crosshatch. This gives you many images along a grid for you to then load into other software to stitch it all together into one large image. This has many uses from making maps to measuring volume. Within the planning, you get a satellite view so you can use landmarks to help plan the flight. Here you also set the altitude and other settings that will be touched on later.

Figure 2: A planned Grid Mission

Waypoint Missions

Waypoint missions are useful if you need a series of images in a line or similar fashion. This would be perfect for pipeline or powerline inspections where you fly the aircraft along in a typically straight line. Also because this is a straight line you can adjust specific events to occur between 2 points, like start video or raise altitude.

Figure 3: A Waypoint Mission

Settings

Within the settings tab, there are many different options. From the homepage, there is one settings page that handles generic settings like max altitude, imperial or metric measurements, gimbal, and compass calibrations. There is also another set of settings for specific automated flights like altitude or overlap or the speed of the flight. All of these settings can impact the speed of the flight as if the drone is higher up it can seem more, so it needs fewer laps. Or the overlap where more overlap will require more laps as the images need to be closer to one another.

Conclusion

MGC is a great app, it allows just about anyone to be able to gather data that they want. All that comes next after the data is gathered is that it is processed then there is a finished product. By keeping the app as simple as it allows the end-user to be able to understand and get to flying as quickly as possible. The app does have some drawbacks being that it is unstable and can crash sometimes but with waypoint flights, it isn't that big of a deal as it downloads the route before the flight commences.

Learning the Bramore PPX Aircraft

 Introduction

The Bramore PPX is an expensive Slovenian-designed aircraft that Purdue owns and is flown by seniors and graduate students within the program. It is launched via catapult and boasts a flight time of about 3 hours. The aircraft flys with its own mapping software that runs similarly to Measure ground control but also operates critical components of the flight like loiter or to deploy the parachute

Figure 1: The Aircraft and Catapult

Ground Station

The Ground station uses a Bluetooth transmitter box that acts as a bridge for the tablet and aircraft for communication. It wirelessly communicates between the devices allowing for edits to the mission in real-time. It also allows you to adjust the landing areas and home location. This aircraft only can communicate with the app and does not allow for manual control so it is critical that when using the aircraft that one ensures everything is charged and stays connected during the flight. If the link is lost the aircraft can loiter and/or return home and land. The C3P app also has the ability to predict where the aircraft will land based on wind direction and strength. This is critical because you don't want to have your expensive aircraft stuck in a tree on landing.

Figure 2: C3P software view w/ take-off, landing, and loiter points

Figure 3: Estimated landing location with 5m/s winds

Aircraft

The Aircraft is a sleek body wing with a large opening in the bottom to allow for sensors to the lookout. It also has a pito tube for accurate airspeed and PPX GPS allowing the user to forgo Ground Control Points (GCPs) as it is so accurate. The flight can last up to 3 hours in ideal conditions meaning that it can cover about an area of 30 km. The aircraft can house a variety of sensors from an RGB 42 MP camera to an Altium multispectral camera. The aircraft does require considerable downtime when swapping sensors and is considered a fragile platform which does cause problems with careless students, hence why it is reserved for upper-classmen.

Figure 4: Bramore aircraft

Parachute

The single most critical component for this aircraft is its parachute. Much like when one goes skydiving you must pack the chute for your flight and if it fails it's on you. There are specific steps that are required when packing the chute in order to ensure no tangles and twists that could cause the aircraft to plummet to the ground instead of land. This was the main portion of material that we covered when learned about the future flight possibilities for 409 (the next course). 

Conclusion

The Bramore is a very advanced aircraft that has a lot of bells and whistles going on. This aircraft is a critical step in learning complex aircraft that follow a checklist to ensure a safe flight. As long as all the steps and procedures are followed the aircraft shouldn't have any issues but miss one seemingly small thing and the whole flight may be put at risk.