“Critically evaluate the strengths and weaknesses of ONE survey technology as a source of primary data for GIS”

“Critically evaluate the strengths and weaknesses of ONE survey technology as a source of primary data for GIS”
Your essay should include observations and examples drawn from the academic literature illustrating
the use and application of the chosen technology. Please note that I do NOT want a survey of ALL
survey technologies: select one of: Total Station, Structure from Motion. Terrestrial (ground based)
laser scanning, Airborne laser scanning. There are some references and materials supplied on the
GY7711 backboard page as well as from the introductory lecture.
2000 words maximum (not including references – which I want to see - or appendices). Deadline
May 28 2020.
CW2 Data Processing of Survey Data (60%)
This component of the module will involve some data processing and requires no more access to
software other than Rstudio. If you do have access to ArcGIS then you can use this. Other alternatives
(such as QGIS or similar) can also be used.
Because we were unable to collect data during the survey, you will make use of some of the
data/photos collected during a previous year’s field class, and kindly contributed by previous students.
1. Total Station Survey Data
In the module intro lecture (see GY7711 blackboard site) we introduced the total station. However,
the ‘show and tell’ session for this was cancelled. So, to review some of the fundamentals of this
piece of equipment, you might like to look at some on-line Bing/YouTube video resources for
operation for very similar devices. There are many of these on YouTube, often of very variable quality,
but a good overview on setting up a very similar piece of equipment (for a Nikon case, but we have a
Leica) is provided by:
https://youtu.be/cMJ7AfcdJSA
This does not cover gathering data via a prism mounted on a pole. More detailed information (albeit
in an Archaeological context) can be found at (though don’t worry about the traversing component):
https://youtu.be/B6vZHqz_Gs4
The survey task for the total station during the field week would have been focused on the surveying
of two mounds (ca. 10-20m in length) which are located on the south side of Victoria Park near the
pond. You will find that a sketch map of the locations is available here (survey > Total Station >
Victoria Park Mounds).
A set of high accuracy benchmarks (survey > Total Station > survey station locations) were employed
to fix the location of the total station, and to then allow the total station to be used to take
measurements of elevation points across the two mounds This is known as the process of resection or
surveying by resection, and is one of the ways we can use a total station for surveying. The general
approach would be to plan a route (perhaps as a series of transect slices) across each mound to be
surveyed in order to collect a sufficient number of points to represent the features.
In the GY7711 blackboard total station folder you will find a folder (oldphotos) comprising some
photos taken by last year’s students of the survey site and the equipment in use. The was using a Leica
total station TS-06. Some specific details of operation can also be found on the Blackboard site.
Once the data have been collected by the total station, the usual approach is to export the data
coordinate triplets (XYZ) to a text file. The following YouTube video displays some very similar steps
for exporting these data in a simple XYZ text file (only illustrative here), and in this case getting these
data into ArcMap (more useful):
https://youtu.be/EhCgk_32hDA
I have helped you by downloading and processing the raw XYZ data points which are in the Blackboard
folder (olddata) in Excel file format derived from several different student groups across the two
mounds from a past field course. These data are in an XYZ format with a CRS that is British National
Grid.
The main processing task is to read-in these point data and interpolate them to form continuous
surfaces, and perspective visualisations of both mounds. This is relatively straightforward in ArcMap.
A document on Blackboard (Survey > Total Station > Data Processing Guides) may be of help.
If you do not have access to ArcMap, then it is possible to get the data into RStudio and
plotted/visualised accordingly. There are many examples of how to do this on YouTube, and you might
like to look at what is available, e.g., https://www.youtube.com/watch?v=b-3KLVM7ank perhaps in
conjunction with some of the web links supplied as part of the interpolation lecture for GY7707.
Different results are generated by different interpolation processes, so you should explore different
methods of interpolation. This is relatively straightforward to do with ArcMap, QGIS etc and similar
can be done with RStudio. Feel free to make use of whatever processing route you can access/feel
happy with.
I am not interested in the (for example) exact R code you use here. However (and this is important):
whatever you do, and in particular if you do make use of a YouTube (or other) processing route or
series of steps obtained from elsewhere/on the internet to transform XYZ data to an interpolated
surface, then please summarise what you did, and cite the source(s) you used. I do not want to guess
either of these – in other words simply giving me the resulting figures/diagrams will be insufficient.
2. Ordnance Survey and Laser Scan Data
Another document on Blackboard (Survey > Ordnance Survey > Digital Data Access) indicates the
series of steps for obtaining Ordnance Survey Data downloaded via Edina. In this case, I am only
interested in the topographic/terrain data (DEM) corresponding to the area of Victoria Park. Had we
surveyed more widely then the other OS and OSM data would have been useful A third set of data
available on blackboard is the laser scanned data derived from airborne survey which has been
supplied courtesy of Airbus(note the copyright and credit statement on Blackboard) and can be found
at (Survey > Total Station > Lidar data). All data can be read into a variety of software that you might
have access to, to produce maps and visualisations in a similar fashion to (1) above. Again, please tell
me how you produced these: figures/diagrams on their own will not be sufficient.
3. The Writing/Evaluation Task
(1) Write up the steps in normal scientific report style of the processing of the above data sets, and
include appropriate illustrative graphics which indicate both the initial points and any subsequent
interpolations/visualisations. You may use include illustrative photos etc from the blackboard site, but
please cite the source(s). This is particularly important when displaying maps etc of secondary data
(data collected from anther source) such as from Ordnance Survey and Airbus.
(2) Compare and contrast the data products above. Discuss the influence of different interpolation
methods on the construction of continuous surface plots.
(3) Both scale and accuracy are very different for each of these three data sets: how do these issues
impact on the representation of the mounds with each data set/source? What do you understand in
relation to data set ‘fitness for use’ in a GIS context, and can you say anything about the ‘fitness for
use’ of each of the data sets/sources used here, which might impact on GIS applications using that
data? You might like to review the paper by Fisher and Tate (2006) to get an idea on the causes and
consequences of error in models of topography.

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