Re: Long time in TriMeshOptimizer

[Roch M. C. <ro...@ro...>]

Hi Again,

I found the headers describing TriMeshOptimizer and think adding  
vertex normals (I already had face normals) might help, and hopefuly  
it will be faster for me to calculate it on the fly while building the  
mesh than have to have TriMeshOptimizer calculate it after.

Any other comments welcome.

Chers,

Roch Comeau

On 9-Oct-07, at 9:42 PM, Roch M. Comeau wrote:

> Hello,
>
> I recently made a small change in how I implemented a marching cubes  
> algorithm to generate a smoother "skin" segmentation from MR image  
> data (see attachments). The change did not alter the number of  
> triangles (about 200k) but did increase the smoothness quite a lot,  
> and more importantly for me, more accurate normals. The side-effect  
> I encountered was a dramatic increase in time to render the image  
> for the first time. When I submit the old skin for rendering for the  
> first time, there is an almost imperceptible pause before rendering  
> (about 1 second). When I submit the second one, I get a 60 second  
> delay before it appears. My program is unresponsive (spinning wheel)  
> until it completes so this is not desired. I ran it under Shark and  
> found that it spends its time in TriMeshOptimizer and mainly in  
> ArePointsSImilar and Q3FastVector3D_Dot within the optimizer.
>
> The old skin had a lot of polygons that were co-planar while the  
> smoother one has more variation in the orientations of the  
> triangles, if that helps. The 3dmf files are almost equal in size  
> (about 11MB) and once the skin has been rendered once, rotates in  
> real time. When I reload the image from file, it also displays  
> immediately the first time.
>
> Any thoughts? I really want this nice smooth skin, but a 60 second  
> pause (vs. 1 second) is a huge hit.
>
> Thanks,
>
> Roch Comeau
> Rogue Research INc.
>
> <New Skin.jpg><Old  
> Skin 
> .jpg 
> > 
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