[Insight-developers] Copying the state of the TimeVaryingVelocityFieldTransform

[Nicholas Tustison]

Hi Kent,

Thanks for tackling this.  I would opt for not saving the velocity field.
I suspect that when somebody gets to the stage of writing out the
transforms for storage, they're more concerned with the transformation
itself and not so much with how they arrived at the transformation
and the velocity field would fall under the latter category.

Nick  


On Nov 15, 2011, at 10:16 AM, Williams, Norman K wrote:

> I've been working on a patch to allow Transforms to be copied.  This
> addresses a gap in the API for transforms: If you read a transform file,
> you only have read-only access to the transforms.  You can manually copy
> parameters from the const Transform to a newly instantiated transform of
> the same type, but this raises two problems:
> 
> 1. Transform state does not exist solely in the Parameters &
> FixedParameters, for several types of Transform.  If you need to make a
> copy you need to know how the internal state has been augmented with 'out
> of band' parameters.
> 
> 2. To copy a CompositeTransform, it would need to copy all its constituent
> transforms.
> 
> Adding a Clone method gives us a way to copy transforms in a single
> method, and the transforms themselves are responsible for overriding Clone
> to make sure the entire state is transformed.
> 
> The TimeVaryingVelocityFieldTransform is the one case where I am not sure
> about how to copy the internal state. It is a subclass of
> DisplacementField, but it has an additional Image-like member, the
> TimeVaryingVelocityField. Plus it also has an interpolator member. Do
> these all need to be copied?
> --
> Kent Williams norman-k-williams at uiowa.edu
> 
> 
> 
> 
> 
> 
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