[Insight-users] System Memory-Help Needed!!!

[Luis Ibanez]

Hi Cspl,

It seems that you are using MultiResolution, in that case
it is to expect that memory demands will go up because you
form image pyramids with both images to be registered.

What you can do in this case is to reduce the number of
pyramid level (although you are already in 3).

Another option is to do the following steps:

1) actually subsample the images,
2) perform a registration with the reduced resolution version,
3) save the final transform parameters
4) perform a single resolution registration using the
    previous transform paramters as initial values for the
    current registration.


The fact is that in the multi-resolution framework, every
level of the pyramid is registered independently of the
others, so the images in the other levels are not actually
required to be there. The current framework create the full
pyramid for simplicity, but you could imaging another strategy
in which the images for every level could be loaded in memory
only when needed.



Regards,


   Luis



-----------------
cspl wrote:
> Hi Luis,
>    Well i could perform 3d Registration after tunning the input 
> parameters...My actual data sets are 512x512x205 and 128x128x205. Since 
> this is a huge data set i started with one slice of each, 
> 2d-Registration, then with 35 slices, then 100 slices, then 150 slices, 
> then 175 slices and now 205 slices. The problem is for the original data 
> sets ie. 512x512x205 and 128x128x205 it is taking nearly 1300Mb of 
> systems memory. Why it is so...The total size of two data sets are 
> 109Mb.. Even it is not performing one iteration but the size of the 
> memory is going on increasing....At last it is giving "Abnormal Program 
> Termination" error message. What could be the problem? Is it because of 
> unsufficient memory or its ITK related error. My system has 512Mb RAM 
> and nearly 1000Mb virual memory...Mine is P3 processor....Even my 
> application is not getting control of the CPU...System Idle Process is 
> getting focus most of the times....What could be the reason....
>     I could get the Registered output for 175 slices each....But for 
> 205....it gives error....Even for 175 slices it takes more memory.....
>  
>    My parameters to the Registration are:-
>    No. of Iterations :- 150.
>    Translation Scale :- 100000.
>    No. Of Bins :- 50
>    Spatial Samples:- 1000
>    Max Step length:- 2.0
>    Min Step Length:- 0.01
>    No. of Levels:- 3
>   
>    Shrinking factors
>        CT images :- 16 16 8
>        PET Images:- 4  4  8
>  
>    What could be the problem??? Is it with the ITK or with system 
> memory??? Any estimate of system memory for these data sets???
>  
>    Please help in this regard.
>  
>    Thanks in advance.
>  
> -Regard,
>    Sateesh.