|
Where DART discusses sub-projects

Thermal Imaging Experiment at the RAC

Monday, March 19th, 2012 by

Background

Permalink for this paragraph 0 DART have proposed a thermal imaging experiment at the RAC in Cirencester. This was originally instigated after viewing the diurnal temperature variations from the embedded probes and wondering what the impact of the vegetation canopy would be on any sensor. This was given life with follow up conversations with John and Rosie Wells.

Permalink for this paragraph 0 For reference we have included the temperature profiles of Cherry Copse and Quarry Field from the April-May 2012 readings from both 10 and 20cm depth probes.

Proposed Consortium

  • Permalink for this paragraph 0
  • British Geological Survey (BGS): Kay Smith
  • DART: Anthony Beck, Doreen Boyd, Tony Cohn, David Stott and Teresa Honore (Leeds and Nottingham Universities)
  • NERC Airborne Research and Survey Facility (ARSF): Gary Llewellyn
  • Royal Agricultural College (RAC): Tony Norris (Farm Manager), Tom Overbury (Lecturer), John Conway (Principal Lecturer) and Nicola Cannon (Lecturer)
  • University of Hull: Graham Ferrier (and UCL colleagues)
  • West Lothian Archaeology Group (Kite and thermal remote sensing): Rosie and John Wells
Associated work
  • Permalink for this paragraph 1
  • Emerald Crop Science: Simon Fox (soils, crop and precision agriculture)
  • DART: Rob Fry and Chris Gaffney (Bradford University: 24 hour ERT readings)

Experiment Overview

Permalink for this paragraph 0 The aim of the experiment will be threefold:

  • Permalink for this paragraph 0
  • to determine the temperature variations throughout a diurnal cycle to understand the impact on temperature dynamics on archaeological detection.
  • to determine the impact of the crop canopy on the detection of archaeological features.
  • to compare the imaging measurements with the results from in-situ subsurface and ambient temperature sensors.

Permalink for this paragraph 1 Thermal imaging measurements will be taken at two sites at the Royal Agricultural College (Cherry Copse and Quarry Field). A low cost thermal imaging camera and a quantitative thermal imaging camera will be set up on a cherry picker to take vertical measurements over an archaeological feature and its immediate surroundings whilst the field is under crop. Concurrent thermal images will be collected at a minimum of 5 minute intervals over a 24 hour period (really?). The area of the field of view will have the crop removed (strimmed) and the measurements re-taken without the crop-canopy so that the impact of any thermal canopy effect can be determined. The imaging data will be compared against the data from both sub-surface thermal probes (buried between c. 10cm and c. 1m and an ambient temperate probe from a weather station (data points collected at c. 1 per hour). In addition, if working, a thermal imaging flight using the NERC ARSF ATM scanner (at 600m flying height – 1m resolution at nadir and 2m resolution at edge) – daily/project configuration to be determined

Dates and Timeline

Permalink for this paragraph 1 We would hope to undertake the experiment the 18th and 22nd June 2012 (all please confirm) with the following activities

  • Permalink for this paragraph 0
  • Day1 erect scaffolding, strim/prep area in field2 (quarry field), erect tents/gazebo etc. check over equipment etc.
  • Day2 take measurements with canopy in field1 (Cherry copse)
  • Day3 take measurements with canopy in field2, remove crop c. 5x5m field1
  • Day4 take measurements without canopy in field1, remove crop c. 5x5m field2 (possible NERC flight)
  • Day5 take measurements without canopy in field2 (possible flight from Bob Bewley)
The earlier we start taking measurements the earlier we are finished. We are looking at c. 24 hours measurements for each site. It would be good to start measuring early evening on Monday so we can be away on the friday.
Throughout the week there are likely to be other meetings including: Simon Fox, the RAC team (in particular to discuss wrapping up the trial, hand-over of equipment, future collaborations etc.).

Logistics

Quarry field issues (John Conway/Nicola Cannon)

Permalink for this paragraph 0 There are issues concerning damage and the impact this has on the crop trials already established in Quarry Fields. To minimise this in quarry fields we would propose to place the scaffold tower within the geophysics grid and include 2.5m pre-strimmed and 2.5m under crop. This will reduce the amount of strimmed crop to a 5 x2.5m area. We would prefer this strategy as we are close to the subsurface temperature probes.
If this unacceptable then we can re-position the experiment. We are constrained by the requirement to keep any area over ‘known’ archaeology. We can follow the intersecting ditches North West or East North East of the area of current installation.

Permalink for this paragraph 0 After conversations with Nicole Cannon, John Conway, Tom Overbury and Tony Norris we have decided to position the thermal experiment outside the trial area following the ditch to the East North East.

Imaging Equipment

  • Permalink for this paragraph 0
  • Low-cost thermal imaging camera (provided by West Lothian Archaeology Group)
  • Quantitative thermal imaging camera (provided by Graham Ferrier (via UCL)
  • FTIR (provided by Graham Ferrier)
  • ASD (provided by DART)
  • LOTS of spare batteries and battery chargers

Mounting hardware

Permalink for this paragraph 1 Each instrument will have different mounting requirements- but the two thermal cameras may be operable using standard ¼” tripod mounts. Tony Norris will provide further equipment if we are short.

  • Permalink for this paragraph 0
  • Jubilee clips
  • cable ties
  • tripod heads
  • ¼”, ?” & ?” whitworth bolts
  • clamps
  • other bolts
  • sockets
  • drill
  • hammer
  • duct tape
  • screwdrivers
  • knife because a degree of improvisation will probably be necessary
  • Rope and box (for raising equipment to the scaffold tower)

Other sensors

Data transfer

Survey equipment

Power

  • Permalink for this paragraph 0
  • Portable generator (Hired through RAC)
  • Fuel can (supplied by RAC)
  • UPS/De-spiker
  • Extension leads
  • Connectors for equipment
  • Ensure waterproof sealing

Support structure (All hired through RAC and including erection and dismantling)

Permalink for this paragraph 0 Two temporary scaffolding towers will be erected. One in each field

Permalink for this paragraph 0 Scaffolding to 7m platform height (with additional safety rail)
Scaffolding platform
Mounting hardware (get a few extra scaffold clamps & bars in case we need to cantiliever anything out)
Ladders
Scaffold poles and clamps to create cantilever for the equipment for the equipment

Permalink for this paragraph 0 Scaffolding will be erected and dismantled by the hire company. Final details will be discussed on site.

Required height

Permalink for this paragraph 0 The height of the scaffolding tower is dependant on the Field Of View (FOV) of the instruments and the size of area we need to cover. This should take in the ditch itself and some of the surrounding area. A minimum size of 5m has been discussed (1m for the feature and 2m either side).

Permalink for this paragraph 0 FOV measurement for 5m ground width: Height = 2.5/tan(FOV/2)*
for a 10m ground width the height is doubled
*note spreadsheets tend to use radians rather than degrees

Permalink for this paragraph 0 The heights for the instruments covering 5m ground width are:
Low-cost thermal imaging camera, 36 degree FOV: 7.7m
Quantitative thermal imaging camera,

Permalink for this paragraph 0 The FOV of the FTIR instrument is so narrow that this will require multiple on / off feature readings.

Data Collection

Permalink for this paragraph 1 We intend to put the instruments on a boom over the scaffolding tower. This may cause problems:

Re-establish Field of view

Permalink for this paragraph 0 It is likely that the mount will need to be retracted and re-established. This will mean that the boom will need to be set at a fixed distance and rotation. We can use gaffer tape as guides, however, we will never get it perfect (especially if we unmount the sensors). To ensure that we can get a comparative fix on the same IFOV after ever remount operation a calibration reding is taken which includes two candles in glass jars placed over known points.

Strimming equipment (supplied by RAC)

PPE (supplied by individuals)

Living (approved by RAC)

  • Permalink for this paragraph 0
  • Water canteen
  • Cooking thing
  • Gazebo (dry area)
  • Tent
  • Local toilet facilities (on the farm – we are OK to use)
  • Handwashing equipment (provided by DART)
  • First aid kit (provided by DART)

Accommodation

Permalink for this paragraph 0 Who is staying and needs accommodation (3 rooms booked at the Travel Lodge) . Please put your names on the left. I assume:

Risk assessment

Permalink for this paragraph 0 Ant and Teresa (Leeds University) are on the case with this. A working draft can be found here.

Issues to Consider

  • Permalink for this paragraph 2
  • Wind Shear as a factor
  • The time between strimming and measurement (1 day) may not be enough for the temperature profiles to settle. If we split the imaging space between the pre-strimmed geo-physics area and the area with crop then we should have resolved this problem.

References:

Permalink for this paragraph 0 Smith, K. (unknown) Review of Thermal Remote Sensing in Earth Science: Science Drivers and Applications http://dl.dropbox.com/u/393477/SharedReferences/NERC_ARSF_TIR_Review_Earth_Science_KSmith.pdf

Permalink for this paragraph 0  

Permalink for this paragraph 0  

Permalink for this paragraph 0  

Tags: , , ,

This entry is filed under RAC, Thermal Imaging. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.