lab_2

Data collection with Multi-rotor UAS Mission

Introduction:

Flying the UAS is always fun and fascinating. However, flying with no purpose is not a good idea to be data analyst. Using applicable UAS software to run the mission is very effective and convenient. According to this lab, I would like to introduce you how to manipulate and adjusting the "Phantom 4 Pro" and its applicable software, in this case, we are going to use "DJI Ground Station  Pro". 

Phantom 4 Pro is one of the multi-rotor UAS. The advantages of multi-rotors over the other types of UAS would be wide rang of the movement. Is is able to move vertically and horizontally. It can be also hovering in the fixed position therefore, user can safely land it. And it needs relatively small area to be landed. Further more, it contains high resolution of RGB camera.

Study Area:

The area we ran the mission, was Gun shelter in Myrick Park, La Crosse Wisconsin. The mission area contains general four different classifications; Grassland, Tree, concrete and water. The general discretion in the area would be different height of trees. Different height of trees may cause the difficulties of flying UAS because of possibility of the crash. There might be possible obstacles such as weather conditions. Because of weather was nice, it wouldn't bother the mission. 

                                          Figure 1. Google satellite image of Study Area.

                                          Figure 2. Image of Study Area from Phantom 4 Pro.

Data collection & Methodology:

Before we are getting in to the mission, we need to download the DJI GSP(Ground Station Pro) app in our I pad and adjust the parameters for the mission. 

                                      

                                                    Figure 3. DJI GSP(Ground Station Pro) app

You need to keep it mind that this app is available and applicable to only Apple product(I-PAD). 

Before we begin, let's interpret the symbol icons at the top of the mission screen.

                          A        B           C       D     E     F                   G                   H                                                                I

                                          J                     
                                            Figure 4. Symbol icons on top of the screen.

A: Home screen

B: Quad-copter Connection, in this case, Phantom 4 Pro.

C: Flight Mode (GPS, Sport and Atti)

D: Satellite Signal (Red:Poor, Yellow: Moderate White: Good)

E: Remote Signal Strength (Red:Poor, Yellow: Moderate White: Good)
F: Camera Connected
G: Aircraft Battery Life
H: Mobile device Battery Life (I-PAD)
I : Take off (Start Mission)

J : Battery Remain estimator

                                                   Figure 5. GSP step 1.

This would be the image that you will the first before you start to set the setting for the mission. The image at the right is showing where your remote control is located at. To begin the mission, you just click the "New" button with plane symbol. 

   

                                                Figure 6. GSP step 2.

It will ask you how would you design the mission. There are several mission type you can try such as photoMap, Virtual Fence, 3D Map Area, 3D Map POI and WayPoint Route. In this case, we use 3D Map Area mission for the lab. 

                                           
                                                 Figure 7. GSP step 3.

This image indicates how would you design the mission whether by tapping which you will design by yourself or let the UAS design for you.

                                    

                                          Figure 8. GSP, making parameters

Because we are doing tapping tool, now you need to put your parameters that how you want to fly your mission. The parameters need to be reasonable and applicable to use. Look around and see what would be the obstacle to your mission flight and where would be the best place to stat flying.  

                                      Figure 9. Parameters of Mission

     

Figure 8. is the setting that you can make parameters for the mission. It has basic and advance types that you can adjust. In this particular mission, we sat the Flight altitude at 70m because, we are assuming that the height of trees around us would be less than 70m and 70m is not too high to get good resolution of image. Therefore, we can prevent the crash. Flight speed was 5.0m/s which is not too fast and slow. Because we had a limited amount of operation time, we made the length as 1416m and 8min 58sec for estimated time. This was our first mission and we didn't want to spend too much time to generate the data image, we got 97 photos which is much less than other research purposed missions. Our front and side overlap were 80% and 73% which are reasonable parameters. More overlaps you do, you will get high accuracy of 3D image you will generate later. However, it will take too much time to proceed. The capture mode was "Hover & Capture". It will stop and take a picture at each point. Therefore, it won't give you blurred image file. 

Result & Discussion:

After we have done with our flight mission, we were able to acquire total 97 photo images. Each photo is saved as JPEG file which is compressed file than TIFF file. Therefore, conversion would be inevitable. The image resolution is 5470x3648 = 19.9Mp and radiometric resolution is 24bit which means 2^24=16777216 numbers of gray-scale does exist. I can say it is decent resolution. The size of the area we have discover, was 3.59HA (35.9Km^2) which was reasonable size of short time data collecting.

Conclusion:

Multi-rotor Phantom 4 Pro is very well being used by many people today. People use this for hobby or research purpose. Therefore it is very approachable and convenient to use. DJI GSP app is one of the useful app that we can easily download and take off the flight mission. According to the lab, we have learn how to manipulate the Phantom 4 Pro and set the parameters for the flight. From now on, we should have been learned what factors might increase or decrease the our quality of mission. We should also know how these considered factors would influence our outcome. 
With all images we have taken, we are going to use Pix4D mapper software to make a 3D map.
Our expectation on next lab would be stitching all images together and make a tie points therefore, we are able to use point cloud and our 3D map will be shown on our hand.

    Figure 10. Happy image cut while we fly the Phantom 4 Pro test mission.