how to assess gnd density distribution with respect to grain sizes and grain boundries using the MTEX

[huihu...@hotmail.com]

Hello Sir,

I have known to use MTEX to solve grain-averaged GND density per grain by the following commands: 

[~,~,eindex] = unique(ebsd.grainId); 
grain_averaged_gnd = accumarray(eindex,gnd,[],@nanmean); 

Now I have three questions, as follows:

Question 1: How to obtain grain size and corresponding grain-averaged GND density at the same time? The aforementioned commands could been only used to capture grain-averaged GND density.

Question 2: Could I plot a cloud map of grain-averaged GND density distribution,  just as the distribution map of GND density per pixel using the command"plot (ebsd, gnd)" ?

QUestion 3: I am trying to assess gnd density distribution with respect to grain boundaries, but I don't know how to extract those.  If it is postulated that  the Euclidean distance to the nearest grain boundary for each pixel point is determined by calculating the distances of a pixel point (x,y) with respect to points along all grain boundaries (xGB, yGB) and the minimum distance for each point is obtained. how to obtain the data set containing the minimum distance from grain boundary and gnd density?

Best regards!

Huihui

[Rüdiger Kilian]

Hi Huihui,

1) some measures for grain size are grains.equivalentRadius or grains.area which are in scanunits, grains.grainSize is in pixels.

2) plot(grains,grain_averaged_gnd)

3) grains.boundary.midPoint gives you the x,y coordinates of the middle of each grain boundary segment, then you can probably compute the shortest distance from each pixel (ebsd.x ebsd.y) the the boudnary. Using grains.boundary.grainId which gives the grain id for each boundary segment and ebsd.grainId which gives you the grain id for each ebsd pixel will come handy to compute the distance for each pixel within each grain.

Cheers,
Rüdiger
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From: mtex...@googlegroups.com <mtex...@googlegroups.com> on behalf of huihu...@hotmail.com <huihu...@hotmail.com>
Sent: Thursday, March 7, 2019 6:43:15 PM
To: MTEX
Subject: {MTEX} how to assess gnd density distribution with respect to grain sizes and grain boundries using the MTEX

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[huihu...@hotmail.com]

Dear Rüdiger,

  

   Thank you for your warm reply.

    1# I used this command "plot(grains,grain_averaged_gnd) "，but error happens as follows:

   Error using grain2d/plot (line 54)

   Number of grains must be the same as the number of data

   There exist 2193 grains. But when I use the command "[~,~,eindex] = unique(ebsd.grainId); 

   grain_averaged_gnd = accumarray(eindex,gnd,[],@nanmean); " to produce a dataset of grain_averaged_gnd, there are 39687 data. the former 2193 data have real numbers, and the remaining data are all NaN. Why ? 

   2# If  it is desirable to remove all boundary grains to attain a data set containing grain_averaged_gnd , corresponding grain diameter(size), and corresponding grain ID, how should I deal with? could you give me an example?

      

Thank you very much for the aforementioned  questions!!

    Best regards

    Huihui 

[Rüdiger Kilian]

Hi,
If I understand correctly, you remove grains whcih touch the boundary? Probably you need to do that first and recalculate grains afterwards again, also updating ebsd.grainId.

Cheers,
Rüdiger
________________________________________
From: mtex...@googlegroups.com <mtex...@googlegroups.com> on behalf of huihu...@hotmail.com <huihu...@hotmail.com>

Sent: Friday, March 8, 2019 7:16:36 PM
To: MTEX
Subject: Re: {MTEX} how to assess gnd density distribution with respect to grain sizes and grain boundries using the MTEX