[Insight-users] LBFGSBOptimizer: bounds for BSplineDeformableTransform?

[niedermayr at trium.de]

Hi Luis!

Thanks for your reply.

What puzzled me was that i thought there is one bound per parameter and
one parameter of the BSplineDeformableTransform is a vector. But as i
already posted to the list, i learned that one parameter of the
BSplineDeformableTransform actually is *one component* of a vector.

best regards,
Chris


> Hi Chris,
>
>
> The type of the Bounds in the LBFGSBOptimizer is an *Array*
> of doubles:
>
>
>    Line 70:   typedef Array<double>  BoundValueType;
>
>
> So,
> you have a bound value peer component of the array of
> parameters passed to the optimizer.
>
>
> In other words, if you are optimizing in a parameteric space
> of 215 dimensions, (e.g. a vector fo 215 components), then
> you pass also an array of bounds with 215 compoents, where
> each bound value correspond to one of the parameters in
> the vector.
>
>
> So if you have a BSplineDeformable transform with 215
> parameters, you must pass two bound arrays to the optimizer.
>
>      optimizer->SetLowerBound( minimumBounds );
>      optimizer->SetUpperBound( maximumBounds );
>
> where minimumBounds and maximumBounds are respectively two
> arrays of 215 components.
>
>
>
>    Regards,
>
>
>        Luis
>
>
>
> ----------------------------
> Christoph Niedermayr wrote:
>> Hi all!
>>
>> I'm confused about how to use the LBFGSBOptimizer with a
>> BSplineDeformableTransform...
>>
>> Facts:
>>  - LBFGSBOptimizer optimizes a set of variables within given bounds
>>  - A bound is a scalar of type double.
>>  - The parameters of the BSplineDeformableTransform are N-dim vectors.
>>
>> Question:
>>   What is the meaning of a scalar bound in respect to a vector-type
>>   variable? The length of the vector?
>>
>> tia,
>> Chris
>>
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>>
>>
>
>
>