Lab 7: Project Proposal - Volumetric Calculations Using Imagery Gathered with an Unmanned Aerial System Equipped with High Precision GPS vs Imagery that Uses GCPs derived from Survery Grade GPS Units

Introduction  

The project that will be briefly outlined in this post will discuss the research of to how to use tie points in conjunction with GCPs to create a geo-accurate imagery, from flights done at separate times over the same area.  Subsequently, with that geoaccurate product produced in the computer software, Pix4D, volumetric analyses will be conducted on multiple debris piles. These measurements will be conducted on imagery produced by 3 separate flights flown on the same day at varying heights and varying resolutions.   Once these geoaccurate products are produced, and volumetric of the various piles are made, maps will be made to show the variation between the flights that were conducted on that day, with a map being made for each unique height/resolution combination. There will be three in total. 

Study Area

The maps that will be created will display the results of research that involves unmanned aerial systems that are equipped with commercial grade, highly accurate real time kinematic (RTK) global positioning satellite (GPS) system, as well as a digital Sony A6000 camera.  When highly accuracy data is desired in most UAS operations, the common practice is to use Dual Frequency survey grade GPS units are used to place ground markers which are than used to create Ground Control Points (GCPs), which are than incorporated into the image processing in the Pix4D software to provide maximum accuracy. However, This method adds considerable cost and time to collecting data with a UAS.  For the sake of this research,  This UAS  imagery will be post-processed using Pix4D software to generate digital terrain models, which will then brought into ESRI software for further analysis.   The ultimate result will be a series of volumetric analyses, where results will be compared between imagery using the UAS High Precision GPS and imagery corrected with GCPs produced by Dual Frequency GPS units. 


The area where this study will be conducted at the Litchfield Mine, a sight that is operated by the Kreamer Brothers construction company.  This sight has a number of piles of varying material types.  The area which these piles are held is enclosed by forest, a retention pond, and a bike trail.  Figure 1 below provides a map of what this area looked like on October 15th of 2015.  The data that will be used to create the volumetrics for this research, however, was collected on March 13, 2016 between 11:00AM and 2:00PM.  The day was overcast with little wind,  which provided great flying and photographic conditions since there was little shadow as a result of low sun exposure.

figure 1: Litchfield Mine Study Area

Methods

The methods that will be used in this lab will be, in part, similar to that of previous labs.   This is because this research will incorporate multiple projects that will ultimately be cross analyzed to compare results, some in methodologies which we have used prior, and some that are brand new.  In essence, three approaches will be taken to provide the results which will ultimately be used to create volumetric comparisons.  Here are the approaches that will be taken:


1. Straight forward processing, relying only on the geolocation provided by the high quality GPS that is on bored of the platform.

2. Processing with Tie points/GCPS.  This approach will incorporate GCP's locations that were recorded at a previous time, while combining those points with tie points that were collected by matching up the locations of visible features that are present in both sets of data - objects that are visible in the data from march and also the data from October.

3. Process the imagery with only GCPs but no tie points to derived from objects that are consistent in both sets of imagery.


Ultimately, regardless of the set of methods used, the final product will be exported into ESRI software for volumetric analyses to be conducted.  Important things to compare as a result of this operation will not only be the sizes of the piles derived from each set of data, but also the amount of root mean squared error that is attributed to the calculations of each pile, relative to that of the same pile produced using another method.

Discussion

Will need to know more about the results to fully discuss the varying datasets and methods used in this research. 

Conclusion

This section will discuss the findings of the research and identify weather or not using high grade GPS and camera equipment on bored the UAS platform provides enough accuracy to eliminate the need to collect GCP points while collecting imagery.  The upfront coast of this technology would be more, but overtime would save money by reducing the labor cost of placing the GCP points and the material cost of cr