[Insight-users] How long does it take do you think ?

[Luis Ibanez]

Hi Tony,

A well tunned registration process should take less than
500 iterations in a Gradient-Descent type of optimizer.


If it takes longer than 500 iterations,
then it means that:


    a) Your have a poor initialization, or
    b) The step length (or learning rate) are too small.


If you were registering images of sizes 512 x 512 x 200, that should
probably should take between 2 minutes and 20 minutes in a modern
computer.

If you are doing PointSet registration, and your point sets have around
25,000 points, then it should take about 20 minutes to register them
using ICP (in a modern computer).

You will find easier to monitor the registration process is you add
a visualization of the point sets using VTK, to the command observer
of the registration.


    Regards,


        Luis


-------------------
tony hakki wrote:
> you are generally right, but in this algorithm when optimizer finds the 
> best results it will be stoped by program not to wait  900 million 
> iterations . I didn't think that it would need 900 million iterations. I 
> thought at the beginning just assign 900 million any how it would not 
> need 900 million  iterations. It has been still runnning :((
> 
> ----- Original Message ----
> From: Robert Tamburo <rjtst21 at pitt.edu>
> To: tony hakki <tony2007vtk at yahoo.com>
> Cc: insight-users at itk.org
> Sent: Friday, March 30, 2007 4:39:08 PM
> Subject: Re: [Insight-users] How long does it take do you think ?
> 
> I've never used this algorithm but 900 million iterations seems like 
> insanity. Assume that each iteration takes either 1 millisecond (best 
> case scenario?) or 1 second (worst case scenario?) then calculate how 
> long 900 million iterations will take. You will probably want to rethink 
> the number of iterations you're using. You may also want to set up  a 
> convergence criteria to stop the registration. You may find that you 
> only need a handful iterations to achieve acceptable results.
> 
> On Mar 30, 2007, at 3:34 AM, tony hakki wrote:
> 
>> hello ;
>> I have tried to implement point set to image registration. My point 
>> set has 151 points(x,y,z),and the image 3D .raw image size is 
>> size = 329 527 181  and the resolution is res=  0.200068 0.200068 
>> 0.200068  .Is there anybody who is expert on registration  process to 
>> guess how long does  computer run  to finish registration process? my 
>> computer has 2.21 GHz processor, and 3 GB Ram . I assigned 
>> numberofiteration as 900.000.000 (900 million) and my computer has 
>> been runnning for 20 hours(yes ,20 hours:))),do you think this is normal?
>> Thanks
>> Tony
>>
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