Mine surveyors explore sensor technologies

October 30th, 2017, Published in Articles: PositionIT

The Institute of Mine Surveyors of Southern Africa’s (IMMSA) North West branch met on 6 October 2017 at Aerial Kopter Solutions’ offices in Wonderboom, north of Pretoria. Besides branch matters, the meeting offered surveyors an opportunity to learn more about current above and below ground measurement technologies. Included on the list of technology presentations were thermal cameras, laser distance meters and unmanned aerial vehicles (UAVs).

The presentation from Yellotec’s Tjaart Broodryk on thermography was well-received. Broodryk, on invitation from sponsors Aerial Kopter Solutions, gave an overview of the different types of thermal cameras and their applications. He explained that temperature anomalies can be indicative of a problem or specific condition, making thermal imagery useful in applications such as identifying heat losses, overheated components indicating of machine health, or detecting defects on solar panels.

Vaughn Vorster, Johan Potgieter, Tjaart Broodryk and Wanda Zonda.

Vaughn Vorster, Johan Potgieter, Tjaart Broodryk and Wanda Zonda.

He also addressed misconceptions around thermal imaging technologies, starting with a breakdown of the three different types of thermal cameras on the market. These are:

  • Infrared or near-infrared (NIR) cameras
  • Thermal cameras
  • Infrared thermography

Infrared (or near infrared) cameras with their very short wavelength measurements are typically used in entry level security applications, Broodryk explained. They are not very sensitive, cannot be calibrated, and don’t allow manual focusing, nor do they provide temperature readings of objects. Then there are thermal cameras which are very sensitive and offer a longer range. While these are more high-end than infrared cameras and can produce digital video output and jpeg photos, they are automatic with fixed-focus lenses, and since they too are not calibrated, they cannot produce temperature measurements. For this reason, these sensors are typically used in monitoring applications, such as animal monitoring or security applications.

Finally, there is infrared thermography in which the cameras are calibrated and can therefore produce detailed temperature measurements of objects within the frame. These cameras allow manual focus for operators to shift the focus onto different elements. The cameras also offer automatic and manual modes which allow the user to set thermal contrast based on the application it’s used for or the type of inspection being conducted.

IMSSA North West branch committee members Sifiso Mdakane, Sybrandt Byleveldt, Ben Maseko and Coenie Pretorius.

IMSSA North West branch committee members Sifiso Mdakane, Sybrandt Byleveldt, Ben Maseko and Coenie Pretorius.

The ability to discriminate between a range of temperatures is important for many applications, and this is where the power of thermography lies. The lower the camera’s temperature range, the better the quality of the sensor. High-end sensors also offer better resolutions and sensitivities for deeper analyses of different elements within a scene, and sometimes even a number of different temperature ranges to choose between. Elements within a scene of the imagery from these cameras can be analysed in detail later.

Employing thermography comes with complexities. The calibration of the devices is very technical. Furthermore, the variables of the environment (including reflectivity and humidity) also need to be set to produce the correct temperature measurements.

Broodryk also explained that common UAV thermal payloads often come with limitations, such as only partial calibration, slow shutter speeds which produce poor quality and distorted images, and fixed-focus lenses.

Aciel Geomatics’ Wanda Zonda presented on underground measuring, and focussed on the Leica S910 Disto which removes the need for tape underground. The point-to-point laser distance measurer has a range of up to 300 m, and can be used for area, distance, angle and volume calculations among other things. It can also level itself electronically. The DFX files in which the measurements are stored according to a local reference system can also be imported and used in Winminop underground mine survey software, as Johan Potgieter explained.

Zonda also reminded participants of the company’s new business unit for detection equipment for underground utilities. AKS’s Vaughn Vorster delivered the final technology presentation, focusing on the company’s product and service offering, including the introduction of its new ROC application service as well as its implementation package – offered as a consultation service to clients.

During the branch meeting, branch chairman Sifiso Mdakane issued a call for technical paper presentations that would grow the organisation’s knowledge base and advance the discipline. In light of recent safety incidents at several mines he also stressed the need for surveyors to promote mine safety and to continue evaluating safety measures and procedures to ensure a safe work environment for all.

The next branch meeting has been scheduled for 2 February 2018.

Photos from the event can be viewed here.

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