“Critically evaluate the strengths and weaknesses of [ONE survey technology - specify which here] as a source of primary data for GIS

GY7711

FIELD DATA CAPTURE

Coursework Assessment CW1 and CW2

CW1 Essay (40%)

“Critically evaluate the strengths and weaknesses of [ONE survey technology - specify which here]

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.

2000 words maximum, including survey plans/images etc (not including references or appendices)

submitted via Turnitin, in the usual way. Deadline June 1 2020.

Reference

Fisher, P.F. and Tate, N.J., 2006. Causes and consequences of error in digital elevation models.

Progress in physical Geography, 30(4), pp.467-489.