Picus

[Dean Lofthouse]

try explaining to a Judge ......... well I hit the tree here and it made a boing noise and here a thud and here a boom noise and see how he understands!!!!!!

 

Well I fully understand what your on about Colin, I'm sure if someone gave the Judge a spliff, he'd see what you were saying too

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sorry Colin, just in one of the take the mick moods tonight

[Marcus B-T]

Have just posted some responses to Thermal imaging queries etc if this interests you.

 

Regrding comparing technolgies what things tell you are they any good etc.

 

The problem with comparing technologies is it is a bit like comparing knives, forks and spoons. They are all cutlery used to eat food but in different ways.

 

None of the technologies and I happily include thermal imaging in this tell you how decyed wood is. They measure properties of wood that are changed by many things including decay.

 

Thermal imaging looks at wood functionality, how well it performs a physiological function (heat transfer). This is altered by decay and other things as well.

 

Picus measures relative elastic modulus and density of wood which are altered by decay but also other things as well

 

Resistograph measurese relative mechanical resistance which is altered by decay but other things as well.

 

In short they are all tools and it is down to the application and use. This is ultimaetly down to training and experience. Because they are all technologies that measure something that is interpreted as decay not actually decay, then they are are prone to error and missinterpretation.

 

An interesting fact is that the more a technology is used the more accurate it becomes, this is how we got the accuracy of thermal imaging to +/- 2% very quickly. Its quick yo use so we could quickly build up experience and tune the product.

 

Enjoy

 

Marcus Bellett-Travers

[skyhuck]

Have just posted some responses to Thermal imaging queries etc if this interests you.

 

Regrding comparing technolgies what things tell you are they any good etc.

 

The problem with comparing technologies is it is a bit like comparing knives, forks and spoons. They are all cutlery used to eat food but in different ways.

 

None of the technologies and I happily include thermal imaging in this tell you how decyed wood is. They measure properties of wood that are changed by many things including decay.

 

Thermal imaging looks at wood functionality, how well it performs a physiological function (heat transfer). This is altered by decay and other things as well.

 

Picus measures relative elastic modulus and density of wood which are altered by decay but also other things as well

 

Resistograph measurese relative mechanical resistance which is altered by decay but other things as well.

 

In short they are all tools and it is down to the application and use. This is ultimaetly down to training and experience. Because they are all technologies that measure something that is interpreted as decay not actually decay, then they are are prone to error and missinterpretation.

 

An interesting fact is that the more a technology is used the more accurate it becomes, this is how we got the accuracy of thermal imaging to +/- 2% very quickly. Its quick yo use so we could quickly build up experience and tune the product.

 

Enjoy

 

Marcus Bellett-Travers

 

Most informative, thank you.

[ScottF]

Whats wrong with the pickey's tomograph: just bore in with a chainsaw, the bar held vertically. If it dissappears very quickly and the sawdust is brown mush: its rotten.

 

I do this sometimes when I am definately felling, it helps when thinking about hinge thicknesses etc.

 

All kidding aside, I'd say there's something to this. When you use a resistograph or similar you get an admittedly small volume of material out that you can interpret. Sometimes having this dust to examine helps support or amend your interpretation of what the device's primary output is telling you. No device is entirely objective- the user still has to make a judgement cased on the sum of the evidence, including, as CB pointed out earlier in this thread, thorough VTA.

[Marcus B-T]

When we use thermal imaging and we feel that the volume of dysfunctional tissue has reached a crital value we always do confirmations with an increment borer. This allows us to look at actual wood quality and can reveal some suprising things. For example we often find dried and cracked wood at the base of large trees without any signs of decay. If the tree is under a great deal of wind presure this is often quite extensive taking up about 50% of the internal volume close to the base of the tree. Also we now know that Phaeolus schwinitzii (think that's the right spelling) causes wood to dry infront of the area of infection and this can cause branches to be shed particularly in cedar. Of course we are helped by knowing just where to put the borer by the thermal images but I personally cannot understand why anyone would be lulled into felling a tree without an invasive inspection before hand.