Pix4D

Introduction

Over the course of the semester, the class has learned many useful techniques and strategies to help survey data in the field. Much of these techniques were learned using either specific survey equipment or more traditional methods. In this final assignment, the goal was to show how the use of UAS and software for UAS can be used to complete most of the tasks that we completed over the semester in a much shorter time. In this assignment, Pix4D was the software used to explore a UAS mission flown by Dr. Hupy over the Litchfield Mine. 

Methods

All of the data that was used in this project was provided to us by Dr. Hupy. The first step in this project was to create a new folder and paste the necessary data in it. Next, Pix4D was opened and a new project was created. Inside the new project, control points were placed to create a processing area for when an image was going to be processed from the mission. The project that was run, creates an orthomosaic and a digital surface model of the specified processing area. Once the project starts to run, it is a waiting game. The software has to process all of the images taken by the UAS during its mission and then mesh them all together to complete a full image. Once this is done, there are many different tools that you can run with the finished product. For example, you will see in the results, a calculation for the volume of one of the sand piles in the mine, the distance of a line, and the area of a specific zone on the mine. These are just some of the ways that Pix4D can be used along with a UAS to survey land. 

Results

To start off, Figure 1 shows the mission that was run by the UAS. Each red dot signifies an image being captured. Starting from the top right and snaking to the bottom left. The red box with a grey fill represents the processing area that was chosen. 

Figure 1. Shows the mission that was run and the processing area that was chosen.

Next is the results of the orthomosaic and the digital surface model. You can see that both the images are in the shape of the previously defined processing area. Figure 2 shows the orthomosaic on the left and the digital surface model on the right. 

Figure 2. Orthomosaic and digital surface model from the project.

Next, when going over the results of the process, Pix4D gives a report to notify you on how the process went. One of the helpful tools provided is Figure 3. It shows how much overlap in images there was in the processing area. The more overlap of images, the more accurate that area will be. It is ideal, in this case, to have as much green as possible. 

Figure 3. Shows the overlap report from the image processing. 

As stated earlier, there are tools that can be run once the processing has been finished. One  of the tools that was run was the length tool. Figure 4 shows the length tool run. The upper right side of the screen shot is where the results are shown. The line segment that is measured is located towards the bottom left of the image.

Figure 4. shows the length tool being used. 

Figure 5 shows another tool that was used in this project. That tool is the area tool. This tool allows you to create a polygon and measure the area within that space. The green area shown in Figure 5 represents the area that was measured. The results are posted in the top right of the image similar to the previous figure.

Figure 5. shows the area tool being used. 

Figure 6 shows the last tool that was used in this project. The volume tool. This tool, as you can imagine, can measure the volume of an object in the digital surface model. To show how this works, one of the sand piles was used. In Figure 6 you can see the mound is highlighted, and the results are posted in the top left of the image. 

Figure 6. shows the sand mound that had its volume measured. 

Conclusion

Over the course of the semester we learned many ways to survey data out in the field. From the total station survey to the ArcCollector survey, I feel that I learned a lot about the different ways of going out to collect data. This UAS and Pix4D assignment was the perfect assignment to end on for this course. It was an excellent way of bringing everything together to show the class that UAS can be one of the most useful and versatile pieces of surveying equipment that we can access. The power that they have to create mosaic images and digital surface models has changed the game. I wish that we would have been able to work with the UAS more through out this class so that we could get an even better feel for its potential.