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Re: [sdpd] Recent Congress and comiing ones about SDPD
Unfortunately texture is univoquely represented by an Orientation
Distribution Function, a 3D object that gives the orientation density for
each orientation of a sample as defined by (alpha,beta,gamma) triplets.
This is a quite large number of points (approx 10^6), say for a resolution
of 5° of the ODF, which increases with resolution.
The ODF in itself is refined through specific algorithms.
daniel
>So perhaps only two basic mathematical treatments are required (or even
>just one, if texture can also be described via a 2nd-rank tensor - if
>you'll forgive my ignorance of texture theory).
>
>Category (b) looks particularly interesting, since it suggests that
>multiple datasets produced via different physical properties, might be
>susceptible to the same mathematical treatment.
>
>Thus the format needed for a single (property-separable) dataset might
>be:
>
>1) 2Theta (or equivalent measure)
> Intemsity
> Property (e.g. anisotropic fwhm)
>
>or for a single dataset taken from a series of multiple datasets:
>
>2) 2Theta (or equivalent measure)
> Intemsity
> dataset property
> symbol
>
> where:
>
>a) "symbol" is a numerical or alphanumerical label which tracks the
>instances of a single line that changes its relative position due to
>anisotropic thermal expansion, variable composition, etc.
>
>b) "dataset property" defines the property (e.g. temperature) which
>characterises the dataset containing that line.
>
>Such a symbol might incorporate a dataset identifier, so that (e.g.) a
>line with symbol "20017" might mean the line with symbol 17, as it
>appears in dataset 2. In that case it might not be necessary to store
>the data as multiple datasets, since instances of the same line from
>different runs could then be identified within a single consolidated
>dataset.
>
>Perhaps an interest group should be formed to pursue these possibilities.
>
>Robin
>
>-----------------------------------
>
>To: sdpd...@yahoogroups.com
>From: Jon Wright <wright...@esrf.fr>
>Date: Tue, 30 Sep 2003 15:15:40 +0200
>Subject: Re: [sdpd] Recent Congress and comiing ones about SDPD
>Reply-to: sdpd...@yahoogroups.com
>
>
>>.... But those who might write the program may well not possess
>>suitable data - I certainly don't. So this would call for collaboration
>>between those with specialist software experience and those with access
>>to relevant datasets. If someone on the sdpd list with suitable
>>multi-environments test datasets were to make these available, that
>>might provide a starting point.
>
>Wouldn't this kind of thing will be easier to develop and debug with a
>series of theoretical datasets? That seems to be the way some people are
>going - it is just too hard to develop an algorithm and test it under
>controlled conditions using real data. If something was working with
>simulated data and is found to be robust with simulated experiment
>errors/problems, then might be the time to try it out on real problems.
>
>There's a chicken and egg problem that no one is going to want to spend
>a lot of time collecting data when there is no program to analyse it and
>no one wants to develop a program without a real problem to solve. In
>this case some theoretical datasets would start the ball rolling, at
>least they could be made to match whatever texture/expansion/peak
>broadening function is implemented. But maybe it's a dead end, maybe the
>indexing problem is already solved anyway ;-)
>
>Cheers,
>
>Jon
>
>
>
>
>
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