Category: Thermal

15 Feb 2020
Llaca Glacier

Mapping Glaciers From Edinburgh To Peru

Sky Tech was approached by Ph.D student Rosie Bisset from Edinburgh University School of Geosciences last year to assist with a custom build drone. After a year of bad press for drones and the climate emergency frequently in the news we were motivated to help with a drone mapping project.

Peru glacier retreat - Two study sites marked shown.
Peru glacier retreat – Two study sites marked shown (Rosie Bisset).

Rosie’s glaciology project was to map an area of the Llaca and Shallop glaciers in Peru. Previous studies had shown large reduction in glacier area in the Cordillera Blanca from 1987 to 2010. These glaciers are an important source of water for the area and research had already shown a reduction of fresh water during the dry season.

One part of the study was to examine surface debris depth and how it affected melt rate. A camera drone needed to be flown in a grid pattern to build a 3D model of the surface. A FLIR thermal camera on the drone would also be used to measure surface temperature differences. In particular to draw links between the thickness of the surface debris and elevation changes, surface movement and water pooling.

Custom Build Drones

This was a challenging custom drone project as the equipment needed to be ready and tested in a few weeks. Sky Tech also needed to provide sufficient training for Rosie and her assistant to fly the drone on the glacier. It had to be a simple to use and quick to deploy. There was some hiking to do to the glacier so the drone needed easy to transport in a backpack. The operating conditions for the drone at high altitude (4600m) and in subzero temperatures were also challenging. Finally a sound methodology to operate the drone and collect thermal data to create a 3D model also had to be addressed.

FLIR VUE PRO
Losing weight by decasing the geotagger and trimming wiring.

The students already had access to a DJI Phantom 4 drone so we chose to modify that given there was insufficient time to build a custom drone on this occasion. We had our concerns it would be able to fly at an altitude of 4600m as it was close to the manufacturers recommended limit. Effectively propellers would need to spin faster in thinner air to create lift, depleting the battery faster. To our advantage we had the fact the air was cold making it denser and easier to create lift. A second thermal camera also had to be attached at additional weight. And finally a requirement to fly for enough time to cover a substantial sized grid that was marked out for study below.

Drone Mapping Training

We started off providing some training on different mapping packages such as Drone Deploy and Pix4D. In the meantime we got started designing a payload package for the FLIR VUE 640 Pro R thermal camera that would be light. We had to speculate if the drone could handle the thin air at higher altitudes (not easy to test in UK airspace) and have a backup plan. We worked on a set procedure for operation in the expected environment, up most was always personal safety on the glacier.

Sky Techs monster Frank.
The creation of Frankenstien (Frank) made from parts of three Phantom 4 drones.

Disaster Strikes

A few days before the trip there was a training mishap where one of the test drones fell out of the sky and crashed. We suspect this was from a manufacturers fault allowing the battery to fall out. The drone was destroyed. In some respects we were lucky as the much more expensive FLIR thermal camera wasn’t attached at the time. (At time of writing DJI have not yet offered a replacement to the students).

Not all was lost, calling around local suppliers we found local store Kooltoyz had a spare frame that had been returned and was missing a camera. This gave an opportunity to make the drone lighter without the stock video camera always being attached. Given all the modifications the new drone was ready – nick named Frank (for Frankenstein).

Local Trials

Longniddry Drone Testing - Thermal gradient as tide receeds
Longniddry Drone Testing – Thermal gradient as tide receeds shown right.

At Longniddry beach we performed some trials at low tide as the surface texture here was a mixture of sand and rocks similar to the surface of a glacier. We also provided advice on use and transit of the equipment and batteries on airlines – not an easy trip and kit has been know to be confiscated.

Frank Mapping Glaciers
Frank mapping glaciers in Peru and Iceland (Rosie Bisset).

Rosie and her assistant left for their month in Peru and we got news back the trip was a success. So much so Frank earned a second trip to Iceland. The required data had been collected. Frank had made it back from his trip half way across the globe. This was fantastic news that the study was a success. Secondly for Sky Tech that our customisations and training worked perfectly for the students to complete their task. Analysis of the data continues at Edinburgh University Geospatial Department. What a fantastic opportunity for us to work with others on a custom drone project. It was rewarding to see others gain confidence with this drone technology.

10 Jan 2020
Roof Inspection By Drone

Roof Inspection And Survey

Conducting roof inspections with drones is providing advantages in terms of speed, coverage, cost savings and more over traditional methods.

What Is a Roof Survey?

A roof survey is where a professional surveyor makes an assessment of the condition of a roof. The condition of tiles, chimney pots, flashing, guttering etc are noted from the ground mostly by visual inspection on the ground or using binoculars. During property transactions roof surveys are carried out and for landlords it is a legal requirement to do so routinely.

A roof inspection provides images alone in a methodological manner which can then be passed to a professional surveyor or repair company. Which really depends on the outcome if it is for an property transaction, warranty or insurance claim or general repair.

A written roof inspection report will highlight the severity and wear or damage that requires immediate action. A detailed roof inspection report is beneficial to property owners to pass to insurers and roof repair companies. It allows accurate cost estimates to be made for repairs and transparency to the client what has to be rectified. Something as simple as finding a slipped tile or blocked gutter could save a lot of money in further interior damage after heavy rain.

A roof survey may take place as part of a wider building survey. It may be neccessary for an professional surveyor to access the internal roof space to assess structural integrity, insulation and membrane material. At the very highest level a roof surveyor would assess a roof by hand using a cherry picker, ladder or scaffolding prising at different elements such as mortar, mastics, tiles and guttering. But this level of attention is very unusual and also considerably more expensive.

This is where conducting a roof inspection using a drone provides considerable advantages. A roof in bad condition could be dangerous to access with risk to the assessor and those below should anything be dislodged.

For the rest of this article we predominantly discuss external roof inspections with no contact to the roof.

Roof inspection utilising a camera drone.

Roof Inspection Using Drones

Advantages
  • Fast to deploy
  • Extensive and concise coverage
  • Access to any style and height of roof
  • Images show exact position of issues
  • Historical record of condition
  • No contact with dangerous buildings
Disadvantages
  • Drone must keep safe distance from public
  • Noise and privacy concerns
  • Visual assesment only, can’t pull or tap
  • Can’t fix simple faults at same time

Drone roof inspections give a reduction in cost, risk, and time to report delivery. On large and difficult to access roofs, drone imagery provides more extensive and concise coverage. Digital imagery can then be uploaded and processed in the cloud for further analysis and compilation of a final report. Sky Tech can advise on the most cost effective solution for your needs.

Example of online digital reporting from roof inspection.

Digital Reporting Tools

Once the roof inspection is completed images and video from the survey are uploaded to the cloud for processing. Digital survey images can be examined remotely by a professional surveyor and the extent of visual faults tagged by severity either manually or with an AI assistant. Images are also on hand as proof to insurers that repairs are necessary.

Is is also possible to create 3D models for special cases such as recording historic buildings. See some excelent examples here.

This is an excellent visualisation tool for virtual and augmented reality either for professional use by say architects or for public displays in exhibits.

3D models also allow the measurement of distance, area and volume when done correctly.

Example of tagged inspection report

Our Inspection Methodology

Our drone roof survey provides a detailed and extensive coverage of different roof aspects and elements as follows:

  • Overview from above building
  • Each roof aspect orthogonal to the slope
  • Ridges, hips, valleys and parapets
  • Chimneys, dormers, bell towers
  • Gutters, downpipes, vest pipes, vents
  • Gable ends mainsonary and pointing
  • Roof antenna, satellite dishes and cabling

How the inspection images are assessed are up to you. Either self assess, ask us for assistance or allocate your own roof survey professional to assess the imagery. The type of fault would can be reported in terms of severity, as well as other minor notes such as wear, moss growth, birds nests. Read more about our roof inspection service here.

References