Field Methods

INTRODUCTION This report is a continuation of the previous post:  Pix4D: Processing UAS Data . In this report, however, data is processed using ground control points (GCPs) to greatly enhance accuracy. For collection methods, visit the previous UAS Platforms and GPS Units for Ground Control post. The purpose of GCPs will first be discussed followed by how they are used in Pix4D and the comparison of results between processing with and without. Finally conclusions are drawn on how GCPs relate to data quality based on processing results.  GCPs as defined by Pix4D, the current most popular UAS processing software, is a characteristic point whose coordinates are known and used to georeference a project and reduce the "noise." Here, the noise refers to the variance in elevation return producing less accurate results. GCPs purpose is to enhance the positioning and accuracy of processing aerial photography producing more accurate 3D models.   METHODS As with the...

INTRODUCTION Unmanned aerial surveillance photography is an efficient, affordable method in gathering data for small to medium-sized projects for a wide variety of uses. These platforms have a high-degree of customization with various attachments to achieve their goals. Besides controlling the flight and collecting data, the data processing can be an intensive process that involves careful attention to produce accurate results. Pix4D mapper is the most common software in UAS point cloud processing and is demonstrated in this report. Data was collected in the previous report UAS Platforms and GPS Units for Ground Control at the Litchfield mine located southwest of Eau Claire, WI.  METHODS Before processing UAS data in Pix4D, a basic understanding of the software and goal-specific requirements should be obtained. To produce a 3D model, the UAS collects overlapping images and calculates elevation based on these images. The distance of overlap should vary according to th...

INTRODUCTION This post is a continuation of the "Improvised Survey Techniques to Create a Digital Elevation Surface" report. The previous report included a method of sampling elevation points within a sandbox and recording the data to produce a digital elevation surface. For this report, the improvised survey data collected previously is normalized. As defined by ESRI, data normalization is the process of organizing, analyzing, and cleaning data to increase efficiency for data use and sharing. This included restructuring notes from the field journal into standardized columns of x,y, and z values for the sandbox grid to transfer into ArcMap. The elevation data was then modeled using various forms of interpolation. The systematic approach to surveying data points allowed a list of elevations to be made on a grid and left out all elevations between. Therefore, choosing the right interpolation method is important because it performs an estimate of elevations between each po...