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Re: [IMP-dev] Grid class




On Feb 6, 2008, at 11:49 PM, Friedrich Foerster wrote:

Daniel Russel wrote:
The differences from the grid used in EMBed are:
- The voxel index is actually a triple if ints. This makes computing
a point in a voxel fast without the large tables used in EMBed. I
think this is the right choice speed wise, but we can always test
(and it is trivial to change).

The reason we had it as single array in EMBed is for consistency with
external programs like fttw, EMAN.
I think that we should keep it like that.

It still has that. Just the index type is different. It also makes it
easier to iterate over the whole thing.

just to add the reason for storing voxels in a 1d array rather than 3d: in image processing, all computations are typically done in loops, i.e.
neighboring voxels are accessed in succession. therefore, it should be
faster in that case, and every program i know of (at least in the em
community) handles it this way.

Its ok. The data is still stored in 1d, the voxel index is used only for iterating - and you can still just loop over the 1d array.