forum.alglib.net

hi


I am using alglib to get trilinear interpolation from ct datasets. I am using vb net.

basically I use xalglib.spline3dbuildtrilinearv to transfer a 512*512*512 datvolume into a spline. each voxel has a value between 0 and 4000.

to get precise values I use the spline3dcalc function about 278217728 times per patient. it takes about a minute.

I know it is hard to say, but do you think you I would profit from the professional version of alglib in terms of time saving?

thank you
sepp

Hello!

I think that switching to professional version will not help you.

Rough estimate of your task gives me about 600 CPU cycles per one spline3dcalc() call. With professional version you will loose about several hundreds of cycles in data transfer between managed and unmanaged threads of execution, so the net result will be either slight increase in performance - or slight decrease.

BTW, do you call spline3dcalc() for random (non-inform) locations? Or you want to get values on equidistant grid?

Hi Sergey

thank you for your fast response! sorry, my response is rather late.

I do two things:

1) 1 rotate the volume by about 20 degrees . to do that, I find three points that describe a plane and than I reconstruct 500 of these planes parallel to the first plane. for each of the pixels I use your spline3dcalc funtions.
(I could skip this step y modifying the step below with offset rotation data but this would be cumbersum to change the code)
I suppose from your question, there is a smarter way?


2) I segment a curved plane within this volume and do raycasts parallel to it to get the final picture. each ray cast uses for each pixel more than 100 times the spline3dcalc




thanks
sepp


by the way: I really like alglib, it really helped me to get much better images, great work!