[Gwyddion-users] Grain analysis and evolution of pits

[Erika Callagon]

Hello,

I'm working on corrosion and have a series of VSI images showing the
formation of pits on steel sample. I've been exploring the Grain Analysis
menu, and saw that there are multiple grain parameters that can be
obtained. My question is: Is it possible to track the evolution of the
specific pits within the software? For my steel sample, new pits form on
the sample, and old pits may expand or disappear. I'm wondering if the
specific pits can be tracked in the time series of images. I'm thinking
that the x and y coordinates of the pits can be used for this analysis, but
my samples have a couple thousands of pits.

I hope I'm expressing the problem well. Any help would be greatly
appreciated. Thanks!

-Erika

[luis vazquez]

Hi Erika,

I guess a possible solution is to crop the image around the specific
pit you want to follow (without re-scaling, that is keeping the sampling
resolution) and then perform the analysis on this specific area.It is
time consuming but it is a way to do it.

Hope it helps.

luis

Post by Erika Callagon
Hello,
I'm working on corrosion and have a series of VSI images showing the
formation of pits on steel sample. I've been exploring the Grain
Analysis menu, and saw that there are multiple grain parameters that
can be obtained. My question is: Is it possible to track the evolution
of the specific pits within the software? For my steel sample, new
pits form on the sample, and old pits may expand or disappear. I'm
wondering if the specific pits can be tracked in the time series of
images. I'm thinking that the x and y coordinates of the pits can be
used for this analysis, but my samples have a couple thousands of pits.
I hope I'm expressing the problem well. Any help would be greatly
appreciated. Thanks!
-Erika
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[Erika Callagon]

Thank you for the suggestion, Luis. For one set of data, I have about 30
images, and I'd like to track a couple thousand of pits. I'm wondering if
there's a way to automatically track the pits (e.g., by indexing the pits
based on their locations) per image, and then know which pits are newly
formed, expanded, or disappeared in each of the images. Or, can this be
written as a module?

Thank you again.

-Erika

Post by luis vazquez
Hi Erika,
I guess a possible solution is to crop the image around the specific pit
you want to follow (without re-scaling, that is keeping the sampling
resolution) and then perform the analysis on this specific area.It is time
consuming but it is a way to do it.
Hope it helps.
luis
Hello,
I'm working on corrosion and have a series of VSI images showing the
formation of pits on steel sample. I've been exploring the Grain Analysis
menu, and saw that there are multiple grain parameters that can be
obtained. My question is: Is it possible to track the evolution of the
specific pits within the software? For my steel sample, new pits form on
the sample, and old pits may expand or disappear. I'm wondering if the
specific pits can be tracked in the time series of images. I'm thinking
that the x and y coordinates of the pits can be used for this analysis, but
my samples have a couple thousands of pits.
I hope I'm expressing the problem well. Any help would be greatly
appreciated. Thanks!
-Erika
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[David Nečas (Yeti)]

Post by Erika Callagon
Thank you for the suggestion, Luis. For one set of data, I have about 30
images, and I'd like to track a couple thousand of pits. I'm wondering if
there's a way to automatically track the pits (e.g., by indexing the pits
based on their locations) per image, and then know which pits are newly
formed, expanded, or disappeared in each of the images. Or, can this be
written as a module?

Depending on what the images look like there are ways to cross-identify
the pits once they are marked in individual images. If the drift is
small then simple methods using centre distances and areas of
intersections for consecutive images could work fine. But there is no
ready-to-use module for that. The fundamental missing piece in Gwyddion
is the cross-identification – which would output something like a table
specifying grain numbers in each image that represent the same feature.
Combined with raw grain property dumps (as from Grain Distributions raw
data) it gives all the necesssary information – but some scripting or
external processing will be required anyway. I might try to write the
identification part as a module that takes a stack of marked images and
dumps a table.

Regards,

Yeti


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