Processing UAS Data in Pix4D

Processing UAS data in Pix4D

The Pix4D software is a Drone Mapping Software for professional drone based mapping purely from images that are taken with an aerial mapping platform. It is possible to use the Pix4D software to create cutting edge results that include but are not limited to Thermal mapping and 3D mapping. It is a useful software that is used in a variety of industries including emergency response, agriculture, mining and real estate. It is a easy to use program that almost anyone can pick up and enjoy.

How to use Pix4D:

Before starting a project it is important to have a image acquisition plan. This is an important step to create keypoints. Key points are a characteristic point found in an image. When 2 key points on 2 different images are found to be the same they are called matched key points, each match Key point will produce a 3D point. The more points captured the more accurately 3D points will be computed. So a high overlap of images is required, at the very least 75% frontal overlap and 60% side overlap is needed. If the user is flying over a homogeneous area such as sand/snow or a uniform field like agriculture lands it is important to increase the overlap to the images by at least 85% frontal overlap and 70% side overlap. Flying higher will also improve the results as well as having accurate image geolocation available.  An available tool for use is rapid check, rapid check is used to verify the proper ares and coverage of a data collection. The Pix4D software is also able to process multiple flights. The pilot does need to make sure that each plan captures the images with enough overlap and that there is enough overlap between the 2 image acquisition plans under the same weather conditions. It is also important that the flight height should not be too different between the flights since this can change the spatial resolution.

In order to produce oblique images the type of data that we need to take is the GSD or Ground sampling distance. It is advised to create Ground Control Points (GCP) if no GCP are used than the scale and orientation constraints can be used. If neither GCPs or constraints are used the final result will have no scale, orientation and no absolute position information. This will make it impossible to use for measurements, overlay and comparison. Finally when the process runs through the Pix4D system we will get a quality report which will report the information computed during the process. This will give us information regarding how many points were acquired the amount of overlay obtained and a summary of the project which can have the AGD, and the amount of area covered.

Methods: 

To use the software we will have to import images that were captured with a UAV device. this could be a multi bladed copter or a fixed winged UAV. After the initail mission is completed and it is time to import the data into Pix4D w must use the Project selection tool. this will import all the data into the program to utilize for later. 

After we select the image properties and where the output file will be located it is time to run the Pix4D program. The Pix4D program to find areas where overlaying occurs and will draw points data and create a area that can be used for three dimensional analysis. 

When the initial process is completed we can then complete a point cloud mesh and create a DSM orthomosaic with indexing. this process takes a long time to complete so it is best to set the program to run and then grab dinner or complete other required work. After the completion of the Point cloud and Mesh with the DSM and Orthomosaic index we then have a completed area that can be used for a variety of other useful applications such as three dimensional maps.

 What is left after the indexing is a summary of what has been completed this holds a varity of information such as the total amount of points collected. The completed GSD and the total area that is covered. what is also completed in the program is a wire mesh of the area selected. 

Conclusion:

The pix4d program is a intense program that can be useful to the geographer who is using the UAV for mapping purposes. by using overlaying pictures it is possible to create a three dimensional map that can be later used for a variety of applications including areas that are quite large. the amount of accuracy that can be utilized is also impressive considering that the amount of time to fly a UAV to the selected area and take the amount of pictures required only needs a small amount of time in relation to how it would be to do the same thing manually. Pix4D is an impressive tool that can be utilized to great extent in areas such as surveying, evacuation data and medical and emergency services.