Hunstanton RTK survey

Hunstanton RTK survey

1. Aims

   • The aim of this task was to survey the Lincoln Square Park. The park is situated in Hunstanton, Norfolk. The reason for surveying the park was to locate every object in the park in case of a modification or renewing of the park was to take place. By knowing where all trees and manmade object is located, a cost estimate and scope for the renewal job would be easier to make.

2. Methodology

   • The RTK GPS Leica 900 was used for the surveying. No base station was used during the survey. Instead of using a base station, the SmartNet functionality was used, which allowed for more accurate measurements compared to using only the GPS signals. Every group member used the equipment in turn. Every object was assigned a class that described what type of object that was registered. Objects such as signs, trees, bushes and lampposts were recorded as single points. Objects such as benches and concrete slabs, that had a two-dimensional extent were registered with multiple points, one point on each corner. The objects were later digitised to make polygons in the post-processing.

3. Issues encountered

   • Line features
     • Because of lack of knowledge about the equipment used, all the points were recorded as lines instead of simple points. Towards the end of the survey we learned that the Leica GPS could record all different entity types, polygons, points and lines. Had we used these entity types throughout the survey, we would have saved much time spent on post-processing the data.
   • Output format
     • The data gathered throughout the survey was exported from the Leica GPS in a CSV format. The CSV format is simply a tabular file containing a set of rows and columns. The file does not say anything about the relationship between the points in the file, therefore, this format does not allow for an export of polygons or polylines. The lack of support for other entities than points means that much manual digitising needs to be done. There are probably other formats available formats available in the Leica GPS, that would allow for export of polygons and lines, however, due to lack of knowledge about the equipment, this was not done.
   • Classes
     • During the survey, classes were created for the objects we recorded, such as “Bench”, “Trash bin”, “Bush”. However, none of these classes were transferred to the exported CSV file in the end of the survey. The reason for this failed export is unknown. The CSV file therefore only consisted of point ID’s and coordinates. This resulted much manual entering of data into the table. Thanks to our efforts of writing down all the information associated with each point ID manually in a notebook as a backup, we still had all the data we needed.
   • Accuracy
     • Bad reception in areas near the trees and the buildings, resulted in poor accuracy for many of the points. Some of the bench and concrete features were unrecognisable and had to be modified a great bit in the post-processing in ArcMap. - The accuracy of the registered points in the dataset varied from 1 cm to 4m.