Thermal Imaging Camera's

[Amelanchier]

The external temperature or emissivity of the tree is directly related to the internal movement of heat.

 

We use observations of heat movement through the tree as a tool. Functional heat flow is directly related to healthy tissue within the tree.

 

The observations are of the current condition of the tree, regardless of whether dysfunction is historic or not. In this way it is possible to identify recently senesced or drought stressed trees. Unlike decay detection devices thermal imaging does not require the wood to become degraded in anyway before it can be identified.

 

Thermal imaging is used to identify the ability of the tree (wood) to hold water and transport it within functional tissues.

 

My point is that historically degraded or dysfunctional wood can affect the external temperature of the tree - but this effect cannot be distinguished from recent trauma. It will simply show a difference.

 

I know the theory and do not dispute the mechanics of TI - I simply maintain that the variables cannot be excluded in the field and interpretation of the images is too ambiguous to be consistently valuable.

[Amelanchier]

Oh come on it is the eye candy that makes all the difference…..

 

The visual image is very useful at providing an explanation for people who find it hard to understand the arboricultural jargon.

 

There is also a big issue with acceptance of one person’s unsupported opinion. A member of the public without a full understanding of trees will be naturally skeptical of the opinion of an arborist whose business is dependant on cutting trees down. In other words they expect a certain amount of bull ****.

 

Seeing is believing at the end of the day and a picture tells a thousand words…….

 

Indeed, but y'know sometimes the emporer really isn't wearing any clothes no matter how pretty everyone tell you they are.

[BootyArb]

Indeed, but y'know sometimes the emporer really isn't wearing any clothes no matter how pretty everyone tell you they are.

 

Well, how did you know...... that's just the way I like it Tony...... :wink:

[ScottF]

I'd personally like to see some strong, evidential and directly-related, peer-reviewed research in an unbiased and respectable scientific journal before putting my money down on a thermal imaging setup, or anything else along these lines, for that matter.

 

Let's see the evidence that it works, rather than some advertising blurb, eh?

[BatiArb]

I'd personally like to see some strong, evidential and directly-related, peer-reviewed research in an unbiased and respectable scientific journal before putting my money down on a thermal imaging setup, or anything else along these lines, for that matter.

 

Let's see the evidence that it works, rather than some advertising blurb, eh?

 

 

 

Scott,

 

More peer-reviewed research papers are in the process of consideration and review for publication at the moment. One has already been accepted by the AA Journal so will be out shortly….. However, these cover its practical and technical applicastion in arboriculture.

 

As for evidence that it works, well that already exists and its value as a tree assessment tool has been very effectively established and demonstrated by Giorgio Catena who is the Thermographer who developed the application for trees. Giorgio has published a number of peer-reviewed papers in different journals. This is unquestionable as far as I am concerned and no further demonstration is required from a scientific point of view.

 

The science behind it is out there in numerous papers in different journals and books, you just need to do some background reading. It dates back to work in the 1960’s that looked at heat movement through trees.

 

The scientific evidence is there for everyone to read and no more papers need be published to explain how it works and why……

 

I have spent a great deal of time over the last 5-10 years developing my own knowledge and understanding of the new insight this technology offers the arboricultural profession. This is what enables me to offer the explanations and responses presented here.

 

If you need more…. Then it is down to you…..

 

I will put in the effort to lead the horse to water…….. but then it is entirely up to you.

 

I will respond to informed questions about the technology to the best of my knowledge and experience in thermography, ecology and arboriculture, accumulated over 20 years of work in the industry.

 

I cannot do your CPD for you………

[arb culture]

Andrew,

 

I'm sitting on the fence on some of the thermal imaging stuff at the moment. As you say, thermography as a method of detecting defects has been peer reviewed time and again and seems to work well if used properly.

 

What hasn't been peer reviewed is the system promoted by Tree Projects Ltd. As I understand it this uses a very different method and incorporates a risk of failure protocol which also hasn't been peer reviewed.

 

I'd be very happy to be proved wrong though.

[ScottF]

 

What hasn't been peer reviewed is the system promoted by Tree Projects Ltd. As I understand it this uses a very different method and incorporates a risk of failure protocol which also hasn't been peer reviewed.

 

 

Quite.

 

From Dr Catena's recent posts on the UKTCI website, I'd suggest that he has gone to some lengths to distance himself from the work being carried out by the Trees Project. Despite his long-standing involvement in thermal imaging across a range of applications, he still describes the relationship between dysfunctional wood and corresponding thermography as being part of a "working hypothesis", rather than a marketable methodology.

 

As regards your comment about "doing my CPD for me", I'd love to know what you mean by that. I've looked into the literature and found nothing whatever to support your claims that this is a consistent, replicable and marketable process. Giorgio's appears careful to caveat his findings with phrases such as "The technique does not allow a truly quantitative assessment of the relative extent of decayed and sound wood, but it appears to be accurate enough to identify trees which merit either remedial action or more precise assessment"(from a 2009 journal publication), and has generally referred to the "potential" of the technology in print, rather than it being "proven".

 

For the record, I have 22 years experience in forestry and landscape, along with master's degrees in forestry and landscape architecture, so I do try to remain reasonably current.

[Andy Clark]

Andrew,

 

I'm sitting on the fence on some of the thermal imaging stuff at the moment. As you say, thermography as a method of detecting defects has been peer reviewed time and again and seems to work well if used properly.

 

What hasn't been peer reviewed is the system promoted by Tree Projects Ltd. As I understand it this uses a very different method and incorporates a risk of failure protocol which also hasn't been peer reviewed.

 

I'd be very happy to be proved wrong though.

 

 

I'd second that!

 

We already have VTA, QTRA, THREATS, Matheny and Clarke, Lonsdale, etc...... the list goes on.

 

Surely it is best to just keep TI as a standalone application, rather than diluting the whole "Tree Hazard Evaluation" realm even further?

 

Is it going to provide more cost effective and therefore viable? Doubtfull, in this financial climate. Although I can see that it would certainly depend on apportioned value of tree and/or target area.

 

 

But until such time as the Uk industry and people like the NTSG etc formulate and agree on a unified approach to THA, the only driving forces will be things like Chapman vs Barking and Dagenham, Poll vs Bartholomew, HSE SIM 01/2007/05 etc....... ie, paper trail mitigation, based on the cheapest possible available option.

 

I think it's fair to envisage that the cheaper methods of Tree Hazard Assessment would be exhausted first, and I'd bet a pound to a penny that most of them would have already stipulated the tree to be felled in the first instance.

 

Sorry Marcus/Andrew, but I really can't help but feel that you're trying to sell a non-product for which there is no market........

 

.... and because of that, "I'm Out".

[Marcus B-T]

There are a number of points here that are valid and should always be investigated fully before any product is launched.

 

Regarding the science behind how thermal imaging works and what it demonstartes this has been well established for around 40 years. The first publications on the relationships between surface temperature and the internal heat conduction and heat capacity were around the 1920's.

 

More recently I have submitted a number of publications on both the science of how it works and its application, as has Giorgio Catena. And there are lots of other more recent applications of thermal imaging in forestry. The university of Melbourne runs courses on its use with wood pests for example.

 

In terms of the overall system developed, it is not actualy a probability of failure system but what it can do is feed information into probability of failure methodologies for risk assessment but it can also feed into classification systems like Metheny and Clark or THREATS. With all tools there is a need for the data provided to be consistent woth the methodologies used to assess the trees.

 

VTA is essentially a methodology based on comparative statistics. You look at the tree and identify those variables, factors or attributes that are different form the population as a whole. Once these are identified there can be a need for further investigation, with thermal imaging the system uses the same methododlogy. The data from the thermal images is compared to what is considered normal for a tree population and is compared statistically. When it is proven that it is statistically significantly different from the rest of the population it is considered for further investigation, at this stage it is usually an invasive methodology. This separation of trees into classifications according to thier condition is just waht is achieved by THREATS and by VTA.

 

Comaprison with actual failures gives the benchmark for the relationship between the progression of the dysfunction detremined by the thermal image and the likelihood of failure. This can also be cross-referenced by comparisons between different populations such as sheltered woodland populations, exposed populations or urban populations. This can be achieved because you can sample so many trees. This has been submitted and accepted for publiction.

 

Incedently data from VTA should be treated in the same way. It should be collated and analysed to find out where the differences are and how individuals that fail are different from the rest of the population. If this isn't done then there is no scientific validity to any assumptions made about the hypothetical correlations between individual defects and the likelihhood to fail.

 

Also accepted for publication is the protocol that you can monitor changes in the thermal properties of wood to monitor recovery and decline. This can also be used to audit VTA methodologies. This allows in part quantification of the reduction in likelihood of failure brought about by an increased frequency of inspection. This cannot be done accurately by VTA alone but it means that ultimately you get an inspection regime that fits the required outcome rather than prophalactic inspection for the sake of it or restricted inspection because there is no justification for the increased expense. This is not to mention targeted inspection regimes and amny otherthings that can be introduced with TI

 

As for the idea that it is a tool that we don't need, as long as there are trees being needlessly removed we need a tool that will give us more information about the internal workings of trees. A great deal has been made about the non-invasive nature of thermal imaging, but it is also the kind of information given that is important. The conductivity and capacitance of wood are optimal when the wood fibre is intact and the cells are well hydrated. As water is removed and the fibres degraded, the thermal properties are reduced. This means that changes in the thermal reactivity of wood give us information about where cells are well hydrated and well organisd and intact. The thermal patterns tell how these are connected up the tree.

 

I have made good use of this information in terms of work carried out on veteran beech trees. By being able to see where the wood has near optimal properties, the trees have been pruned and the regrowth has been excelent. Just writing this up for publication at the moment. The best bit is that in many cases the trees could be 'left to their own devices' without any worry about them failing, many with K. deusta as a purely saprophytic growth, others with superficial growths of M. giganteous. Many with Ganoderma sp. This is quite important since I am convinced that many older beech trees go into a kind of transient veteran stage caused by drought from which they recover. The problem is that work is then carried out that accelerates the decline of the trees, where as if they had been left to recover then they would have done so and the only work would be the occasional removal of dead wood.

[Amelanchier]

Giorgio's appears careful to caveat his findings with phrases such as "The technique does not allow a truly quantitative assessment of the relative extent of decayed and sound wood, but it appears to be accurate enough to identify trees which merit either remedial action or more precise assessment"(from a 2009 journal publication), and has generally referred to the "potential" of the technology in print, rather than it being "proven".

 

 

I was looking along those lines earlier Scott. In the same paper (Arboric Jour Vol 30 No 4 March 2008) Dr Catena goes on to explicitly state [my emphasis in bold]:

 

p 260 "Numerous case studies have been cited to show that extensive zones of decay are represented by correspondingly extensive 'cool zones' on thermal images. This relationship has not been investigated precisely, but it has been broadly verified by 300 general comparisons... Nothing is yet known about the relationships between thermal images and the different kinds and stages of decay (Catena 2003)."

 

p 261 "...thermal images cannot provide such measurements [extent of decay] precisely. Also in certain cases, large cool zones have been found on stem bases that, once the tree was felled, showed only small volumes of decay above ground level."

 

p268 "the technique does not automatically distinguish between different kinds of alteration... ...with current knowledge, thermal images do not precisely measure the dimensions of features such as cavities."

 

 

 

Compare and contrast this with the following claims from the Thermoecology website [again my emphasis in bold]:

 

"Thermal imaging is a proactive tool that allows the observation of physiological function in trees and can inform judgements about the balance between healthy wood and the progress of decay."

 

"The extent of these changes compared with what might be considered optimal wood functionality can be detected and quantified."

 

It offers a very high degree of precision + - 2 %

 

Combined with a high degree of accuracy + - 0.1%

 

"... provide a visual interpretation of a tree’s physiological function and enable the identification of decay and dysfunction."

 

 

 

And this from the Trees Project Ltd site

 

"Thickness of healthy wood can be accurately calculated with our new comparative imaging technique."

 

"The method is not only used to determine the extent of decay but also the amount of healthy tissue present that will contribute to the continued survival of trees."

 

 

 

IMO the claims are not supported by the existing research , they overreach it. If there is some more in the pipeline - great but it is a bit much to simply tell us that its out there some where and we should go and find it!

 

Will it say "I'm not doing your CPD for you" in the references section of the new paper?

Edited January 11, 2010 by Amelanchier
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