Pix4D Processing Software

Introduction

Pix4D is an imagery processing software that is able to process data collected from various UAS systems. It is currently the best processing software for constructing point clouds. The program is able to process the data so it can be used in Geospatial programs like ArcMap. The program is easy to use and their online manual is easy to use. The processing part is time consuming but the speed can be adjusted dependent on the output quality required.

Preliminary Questions?

Look at Step 1 (before starting a project). What is the overlap needed for Pix4D to process imagery?

The recommended overlap is 75% frontal overlap (flying direction) and 60% side overlap (between flying tracks).

What if the user is flying over sand/snow, or uniform fields?

                Sand/Snow require a higher overlap of 85% frontal and 70% side overlaps. They also require the exposure to be set to get as much contrast as possible. Uniform fields require same overlap and that the UAS is flown at a higher altitude.

What is Rapid Check?

                It is an option for quickly processing data but in turn lose quality. It is a quick way to check data while in the field.

Can Pix4D process multiple flights? What does the pilot need to maintain if so?

                The program can process many flights if the flights were maintain at the same altitude.

Can Pix4D process oblique images? What type of data do you need if so?

                Yes as long the images have angles recorded for the data.

Are GCPs necessary for Pix4D? When are they highly recommended?

                You do not need to place GCPs but the lack of GCPs will create less accurate data. It is highly recommended to use GCPs to reduce the amount of possible vertical and horizontal inaccuracies.

What is the quality report?

                The quality report gives a summary of all the data processed. It will allow you to verify the accuracy of the data before you start to use it. It shows you how the data was processed and parameters to the data. It also can show you areas where the data needs to be fixed or recollected.

Methods

For this lab we were giving two sets of separate flight logs. We were then instructed to process this data in Pix4D. You first open up PIX4D and create a new project.

It is important to name the project accurately. Include the date, site, platform, sensor, and altitude. Then add all the image flies from one of the flight logs. We will do the second flight log separately. Here you can look at the data points and edit the camera settings so they are correct for your camera.

Then select process data with 3D maps.

 Then click ok. You will now do the initial processing. Make sure to uncheck point cloud and DSM options. This will slow down the whole process if not unchecked.

You can edit the processing options to choose speed and quality of the output data. Once the initial processing is completed it will give you a quality report.

The quality report is very useful because it will tell you the accuracy of the data and whether you should proceed to steps 2 and 3 of processing. Once steps 2 and 3 are completed you can turn of cameras and turn triangles on to view the map created from the processed data.

There are some areas where the overlap is poor. These are areas at the edge of the map where the UAS made fewer passes. The middle of the map the UAS goes back and forth creating plenty of overlap.

Video Animation of the Data
https://www.youtube.com/watch?v=4-CIyOPjLMs&feature=youtu.be

Conclusion

Litchfield Map 1

Figure 1 Litchfield Flight 1

Figure 2 Litchfield Flight 2

Conclusion
Figures 1 and 2 show the DSM data collected from the Phantom 3 processed with Pix4D. There is some distortion in the corners where there was lack of overlap.
Overall the program is easy to use. The data processing is time consuming but as long as the pilot collected good data, the processing yields great results. The data can then be imported to ArcMap to further be analyzed as in figures 1 and 2.