Created by Brenton Crawford.

Currently, there are 4 main types of core photography systems available for mining companies to purchase or self-build.

The aim of this blog is to make an assessment of those photography setups based on our experience at Datarock in processing millions of metres of core photography to extract quantitative information. 

Criteria for this review

Light consistency – the ability to repeatedly illuminate the images with the same amount of light  

Light quality – how even and diffused the light is to reduce reflections

Mobility – the ability for the system to be transported both in the coreshed and between sites

Maintenance – how much effort is required to maintain the system to a high standard.

 

What won’t we be discussing

Costs/pricing – Costs for any photographic systems like the ones reviewed here are extremely competitive and low cost compared to nearly any other data collection device. Cameras themselves often make up 50 – 90% of the total costs of these types of systems and in our opinion cost should not be a major factor when choosing a traditional core photography system like those discussed here.

Cameras – Commonly used DSLR cameras are compatible with each of these systems, we will do a more detailed review in another blog.

Setup – The way the image is prepared, calibration and the curation of the core itself are discussed in the blog below:

https://datarock.com.au/blog/how-to-take-an-analytics-ready-core-photograph/

Core scanning or scanline cameras –  We will review these core scanners/imagers in a later blog.

 

Type 1 – Basic camera frames

 

Description

Beyond somebody using a smartphone or handheld device to photograph their core (which we do not recommend), a camera frame with a DSLR camera attached is about as simple as it gets. Basic camera frame systems are most commonly self-built by sites although some frames can be purchased. These systems do not have inbuilt lighting using whatever light is available either in the coreshed or outside in the sun. The frames can either be mobile and are able to be lifted and taken to the core, or they may be fixed on roller racks or fitted with wheels to roll along the core racks.

 

 

Figure 1 – 3D rendering of a basic frame camera setup showing its position above the core and the light source being represented by fluorescent coreshed lighting.

 

Benefits

• Mobile and low cost. 
• No external power required.
• Camera is reasonably well-centred above the box at a fixed focal length.

Challenges

• Inconsistent illumination due to the lack of a consistent light source; when you analyse the imagery from these systems you can commonly see regular or cyclic variation in the lighting as the sun moves or the core moves through the coreshed.
• Depending on the position and type of lighting in the coreshed, the undiffused light from fluorescent lighting can cause significant reflections down the centre of the core.
• The frame itself can cast shadows, particularly when used in outdoor environments.
• Camera settings are usually set to automatic due to the fluctuating lighting conditions, meaning there is even less consistency in the colour/texture information being collected.

Opinions

In 2024, using camera systems that do not either diffuse light or have consistent inbuilt lighting would typically be a no-no. In exploration projects that are highly mobile, it would be preferential to use a system like this over a handheld device.

 

 Rating

 

Type 2 – Camera frames with lighting

 

Description

The next step up in terms of complexity is a camera frame combined with standardised lighting such as LED light panels. These systems are commonly self-built or purchased from mining suppliers. LED light panels are inexpensive and readily available. 

Figure 2 – 3D rendering of a camera frame with inbuilt lighting represented by LED light panels

Benefits

• Moderately mobile, especially if lights are on battery power.
• More consistent lighting than Type 1, driven by the light panels. Light is not entirely consistent due to environmental light not being blocked out. These types of systems can be paired with a block out shroud to eliminate external light (see type 4).
• The camera is reasonably well-centred above the box at a fixed focal length.
• Camera settings can be optimally set and generally left fixed due to the consistent lighting.

Challenges

• In some scenarios, environmental light from the coreshed can cause some inconsistencies in illumination (less significant due to the onboard lighting).
• There are many types of lights that can be used, but not all lights will provide optimal results. The placement and diffusion of the lights (explained later) will determine the overall quality of the image; if done poorly these can cause significant reflections.
• If lights run off mains power, the system is difficult to move and would likely be fixed in position.

Opinions

Having onboard lights is a big step up from the basic frame cameras, but care needs to be taken to ensure the right lights are used and configured in the appropriate way (low and to the sides, not directly above, high CRI – see final section).

Rating

 

Type 3 – Light diffusing systems

 

Description

These systems can be bought and are occasionally built by draping a light diffusing material (such as nylon) over the system to ensure that any light that enters the image has been diffused. Light diffusion scatters the light and results in softened light that has no strong point sources and is therefore less likely to cause reflections. 

Figure 3 – 3D rendering of a camera frame with light diffusing shroud on a roller rack

 

Benefits

• Mobile, lightweight, commonly on wheels (often fixed on roller racks).
• Light diffusion minimises reflections by reducing point sources of light.
• Camera is well centred above the box at a fixed focal length.
• If the camera is located in a consistently illuminated part of the coreshed the camera settings can be optimally set and generally left fixed due to the diffused lighting, but light variability. needs to be monitored (if located near variable external lighting then this will be an issue similar to type 1 systems).

Challenges

• No onboard lighting means that there can be inconsistency in illumination; this can be addressed with the addition of lights which are readily available and simple to install.
• The light diffusing material needs to be kept clean and replaced regularly to maintain consistency.

Opinions

This setup has great potential when used with appropriate lighting. Photographic systems similar to this with consistent lighting attached have produced some of the best quality traditional core photos we have seen.

Rating

(with consistent lighting attached)

or

 

if using coreshed lighting

 

Type 4 – Systems with consistent lighting and light blocking shroud

 

Description

These types of systems are typically purchased and contain the benefits of consistent lighting and also removing any external light sources. These systems create the most consistent lighting, but can also suffer from reflections due to the relatively confined space where light can be placed and diffused.

Figure 4 – 3D rendering of a camera system with inbuilt lighting and a light blocking shroud. Note front flaps of the shroud are removed for the purposes of this illustration.

 

Benefits

• Consistent lighting with the same illumination for each image (as long as the doors are closed).
• Camera is reasonably well centred above the box at a fixed focal length.
• Camera settings can be optimally set and generally left fixed due to the consistent lighting.

Challenges

• Typically need to be fixed in place due to their size and power cabling.
• Lights are commonly not diffused and mounted high above the core resulting in significant amounts of reflection.
• Bright reflective interiors of the shrouds can be prone to getting dirty so need to be regularly cleared and eventually replaced.

Opinions

A very good choice of camera system provided the lighting is configured correctly to reduce reflections. This type of system has some of the best colour consistency due to very consistent and controlled illumination. Critical to keep the doors closed and the interior clean to maintain this consistency.

 

Rating

 

Getting the light right!

Here, we have reviewed the main variations of how core photography is currently being done in the industry. It should be clear that one of the key concerns when choosing a camera system is the quality and consistency of lighting. 

Your camera system should provide you with a consistent and repeatable digital dataset that collects and represents the colours and textures within your geology as truthfully as possible.

Light is more important than the camera because it is source of what is being measured by the camera.

If we use seismic data collection as an analogy, the light is the seismic source (like an explosion or vibroseis truck) and the camera is a geophone that will measure the seismic waves. If you do not get the source right, then no matter how good the camera, you will not be maximising the quality of the data.

Like any other sensor that is used to measure the geological material, it is important your choice of core photography system is made with the same rigour as you do when choosing a laboratory or a geophysical sensor.

 

A light recipe for success

 

The typical recipe for high-quality and consistent lighting in a photographic system is to use lights that are mounted off to the sides and not directly above the core. LED light panels are a popular choice to use; they can be quite large and have tunable CRI values and intensity/brightness.

The lights should ideally then be diffused either by passing them through a light diffusing nylon or what is commonly referred to as a softbox. 

The result should be diffused light that is hitting the core at a relatively low angle (figure 5). To stop external light from above causing reflections and changing the amount of illuminations, we also recommend to put black out shroud over the top of the system – especially above the core tray.

Figure 5 – Schematic diagram showing the configuration of lighting to produce low angle diffused light that commonly produces high quality low reflection core photos. The black out shroud would sit around this system (see Type 4).

Conclusion

The reward for getting your core photography system set up in an optimal way, is imagery that provides significantly more visual information for geoscientists and engineers to visually look at, as well as a quantitative datasets that contains valuable information that can be extracted with Machine Learning.

The link below contains several blogs that show off what can be extracted from core photography with Machine Learning.

https://datarock.com.au/explore/

As part of Datarock’s trial services we can review your core photography practices and provide an assessment of what can be extracted from your current core photography as well as give advice on how to improve and maximise the quality of your core imagery.