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.

Pix4D

 Introduction

We were introduced to Pix4D over the span of 2 weeks. The first part was to get comfortable with the tutorials and help information and the second week was about the data processing. The software can be pretty demanding when it comes to processing and required us to use the computers in lab to complete the assignment. Pix4D has 4 steps it goes through when processing the data, Initial processing, analyzing the quality report, point cloud and mesh, and DSM.

Processing

The software looks for GPS points and starts arranging the photos accordingly. If any issues arise then it will show up in the quality report. In the quality report, the software will point out any issues with the data before it continues with the processing. Next, it goes through and starts meshing the images together. Finally, the software gets to the final stage where it has all the images put together and ready for viewing. Figure 1 here is an example photo from one of the processes. This is what the final product looks like.

Figure 1: A processed Raster

Final point clouds

Depending on how many images are taken will depend on how clear the processed photo will come out. Figure 2 is of a Raster that only had 15 photos. This made the picture have a lot of black space where the resolution wasn't good enough for the program to make an exact copy of the area. Next, there was a raster that included photos taken on angles. This didn't impact much of the processing and also made the image have "holes" within it. This can be seen in Figure 3. Finally, there was a Thermal Raster that we had to process. Due to the file type, it cannot show in Pix4D but after we transfer the file into ArcGIS the image can be seen. The Raster that was from this is Figure 4, The triangles at the top are where the photos were taken but again due to the file type, there is no image below. 

Figure 2: A Raster with only a few photos

Figure 3: A Raster with photos taken not at 90 degrees

Figure 4: The invisible thermal raster

GCPs

We then looked into using ground control points to give more accurate positing data for the images. This can be useful if the images aren't geotagged with an onboard GPS. After inserting the GCPs into the data you need to reoptimize the point cloud in order to take into account the GCPs. Once they are imported you must tell Pix4d where the GCP is on 4 images, this gives it some reference points to figure out exactly where the GCP is in relation to the images taken. Figures 5,6,7 are of 3 different aircraft and with 5 GCP points. There were 6 GCP points available but due to the lack of images in some of the data, it could cause the mapping to be messed with if it was included so there are only 5 GCP points. After the project is done being reoptimized you then should re-check the quality report to ensure that the geofencing box has a green check, ensuring that the program knows where the points are. Figure 8 is of this table and because it knows where the points were to a close degree.

Figure 5: A6000 images with GCPs

Figure 6: Mavic 2 Pro images with GCP

Figure 7: XT2 images with GCP

Figure 8: Green Checks within the report

Conclusion

By using Pix4D one can create very accurate 3D models that can be even used for measuring specific parts. The one drawback of this software is the hardware requirements and if your computer is on the low end you could be processing the images for a very long time.

Datums

 Introduction

Within this lab, we were taught the importance of data collection and to ensure that the data that is collected is right. The first and most important thing is the metadata of the flight, this contains flight-critical data such as the time of the flight and what aircraft did the flight. The next most important thing is that the GPS data that is gathered is in the right format, as reversing latitude and longitudinal numbers can give one drastically different locations on Earth. 

Ground Control Points

Before a flight Ground control points (GCPs) are place around the area. These give accurate position data to the aircraft and allow for fixed points where the data was gathered. The coordinates are given in an XYZ style that the computer then can use to place the point precisely in space. X is longitude, this makes sense as the X-axis on a graph goes in the same direction as longitude lines, Y is the latitude and again follows the same reasoning. Z is the vertical distance.

Ellipsoid vs Ortho

There are two different types of height measurements within aviation. These come about due to the fact that the Earth is not a perfect sphere and there are different ways to measure the height of the aircraft. If you ask a pilot what are the two measurements they would say mean sea level (MSL) and above ground level (AGL) this corresponds to the ellipsoid and ortho measurements, but it is important to get them right as flipping them might cause an accident or poor data collection as a result. Ellipsoid height is the difference between the actual earth surface and the ellipsoid thus its AGL, while ortho is the height compared to average sea level (MSL). Figure 1 shows an image of how ellipsoid and ortho heights are taken.

Figure 1: Ellipsoid vs Ortho

Conclusion

Datums are very important when it comes to gathering data. When you have to gather location points and determine the altitude it is important that you use the right measurement. By using ArcGIS to process your data you can see if there are any issues with the data. In completion of this lab it was obvious that it is important to take down the data and in the right way, as if we didnt have the proper GCPs within the lab all the data would have been trashed.

Measure Ground Control

 Introduction

Measure ground control is an application that is meant for the future UAS company to be able to manage data collection, its fleet, and safety for all flights. Its base software is built on Airmap, an airspace service that digitally tracks important flight information. This allows the app to do critical functions to ensure that the flight is done right and safely. Personally, I feel that this software is a great start for any UAS company that has to gather data and does so with a team mentality.

Roles

There are many roles within the app and they all do different things. This makes it so that people only get the information that they need and not a whole lot of "fluff" that could cause them to get distracted. The first role is an Admin, they are responsible for adding roles and flight plans. Next is the pilot, they can view flight plans and collect data. The data analyst's job is to take the data gathered within the app that the pilot gathered and process the data accordingly. Finally, there is the drone program manager role, They can see al the missions and control when what mission is executed. All of these roles work together to form all of the stages necessary to do GIS work.

Flights

When managing flights the app has a few different options. The pilot in the field can access their assigned missions and can start and stop missions. They can also see other pilot's missions so they can be aware of other flight ops that might be happening in the area. The flights have a few different options as well. There are grid flights, useful for gathering data of a wide area and there are waypoint flights, useful if you are going to fly a pipeline or phone line for inspection. The app can manage the camera settings or if required you can tell it to use manual settings that the pilot will program in during the flight.

Safety

 Airmap updates with weather and TFRs and because Measure is built on this it also has those features. Finally one of the last but most important things that this app includes is LAANC authorization. This is Low altitude authorization and notification capability, this notifies other aircraft and ATC that there are drone ops taking place within an area so that manned aircraft can be routed around if required. This clearance can also be requested within the app and by giving your name, flight plan, aircraft, and duration of the flight, along with your 107 number. This means that the flights that the UAS organization is conducting are done safely and within the law.

Conclusion

Measure ground control is a great application that provides a skeleton structure for any up and coming UAS company to have a place to start and a way to manage its employees. It also ensures that the right data is gathered and in the safest way possible.