[Insight-developers] Is this right? -- beefed up GetOutput() doc

[Miller, James V (Research)]

Mark,

Your description is on the mark except the following...

    * (This pipelining method is preferred where feasible since it
    * permits more efficient use of memory and other resources.)
 
It turns out all the three examples in your description use the same
amount of memory and resources (within the size of the meta data in an
image which is pretty darn small).

Perhaps this would be a good place to discuss how someone can request
a particular portion of an image be updated.

   image = someFilter->GetOutput();
   image->SetRequestedRegion( someRegion );
   image->Update();



> -----Original Message-----
> From: Mark Foskey [mailto:mark_foskey@unc.edu]
> Sent: Tuesday, February 11, 2003 11:26 AM
> To: insight-developers@public.kitware.com
> Subject: [Insight-developers] Is this right? -- beefed up GetOutput()
> doc
> 
> 
> I needed to access some image information partway through a pipeline, 
> and it took me a while to settle on the proper way to do that.  I 
> thought it would help clarify things if the GetOutput() documentation 
> were more detailed.  I wrote up the following, but since the 
> dashboard 
> won't catch any factual errors, I thought I'd post this 
> before checking 
> it in.  (The fact that I feel the need to seek confirmation 
> argues that 
> the documentation would be useful.)
> 
> The User's Guide was helpful in this, but I thought this information 
> ought to be available from the doxygen docs as well.
> 
>    /** Get the output data of this process object.  The output of this
>     * function is not valid until an appropriate Update() method has
>     * been called, either explicitly or implicitly.  Both the filter
>     * itself and the image object have Update() methods, and both
>     * methods update the image data.  Here are three ways to use
>     * GetOutput() and make sure the image data is valid.  In these
>     * examples, \a image is a pointer to some Image object, and the
>     * particular ProcessObjects involved are filters.
>     *
>     * \code
>     *   anotherFilter->SetInput( someFilter->GetOutput() );
>     *   anotherFilter->Update();
>     * \endcode
>     * (This pipelining method is preferred where feasible since it
>     * permits more efficient use of memory and other resources.)
>     *
>     * \code
>     *   image = someFilter->GetOutput();
>     *   image->Update();
>     * \endcode
>     *
>     * \code
>     *   someFilter->Update();
>     *   image = someFilter->GetOutput();
>     * \endcode
>     * (In the above example, the two lines of code can be in
>     * either order.)
>     *
>     * Note that Update() is not called automatically except within a
>     * pipeline as in the first example.
>     */
> 
> 
> -- 
> Mark Foskey    (919) 843-5436  Computer-Aided Diagnosis and 
> Display Lab
> mark_foskey@unc.edu            Department of Radiology, CB 7515, UNC
> http://www.cs.unc.edu/~foskey  Chapel Hill, NC  27599-7515
> 
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