Vector blur only working on one mesh - help please!

Support Compositing and Post Processing
#1

I’m probably making a very stupid mistake here, but I’m trying to apply vector blur to a scene and it’s only blurring one of the meshes.
Here’s a WIP still:
http://www.martylog.com/comedycuts/lh02.png

And a WIP of the animated shot:
http://www.martylog.com/comedycuts/animtest2.mpg
The head is blurring, but not the body and can’t figure out what I’m doing wrong. I’ve used Vector Blur many times in the past without any trouble. I’m using the latest Windows build of Blender (2.47).
Everything is on the same layer and I’m using the default vector blur settings, I have Vec selected, every layer turned on, I’ve got Do Composite selected… I’m all out of ideas. Any suggestions as to what else I could troubleshoot?

#2

I’m not shure about this, but in frame 414 it looks like the left hand is blurring as well.
Perhaps its just a matter of speed. Did you try, raising the BlurFac in the Node. just as a test.
But otoh, might need new glasses, if there is no blur. :slight_smile:

Pat

Edit: Nice Lighting BTW!

#3

Uploading a .blend file would be much more helpful than the description you provided.

It’s hard to tell from your low res/low quality videowhat is actually going on but I suspect that it’s one of two things… 1). an improperly set alpha channel, or, 2). another Z-Depth effect is interfering with or “clipping” the alpha trails (the previous and next frame samples) which because the pixels in these samples do not contain any depth buffer information and are therefore disregarded. This can hapen if you use vector blur in your node setup B4 piping the result into a Zcombine node. You can also see this happen when you try to Zcombine any combination of render layers in which one or more of the render layers contains a z-transparent material. In the latter case you will not be able to see any objects from another render layer which reside behind the z-trans material because z depth effects within the nodes compositor are basically boolean operations performed on the individual pixels within an image set placing one pixel in front of another. Transparent pixels in the foreground become “true” meaning that they get “turned on” (set visible) while pixels behind them in the image set become “false” and are turned off (set invisible) thereby asigning any semi transparent pixels to be fullly opaque. So, with depth buffer effects, any depth-buffer-less image data (alpha channel effects such as halo materials and halo spot lamps, non mesh objects, or any 2D image data generated within or imported to the composite nodes) gets tossed aside like a sack of dirty laundry.

Vector blur looks like it’s working over the entire character to me. You can see how flat the shading falls in your boy’s hands when they’re moving quickly (you have to enlarge it to see it). Do you have a defocus node upstream from the vector blur node or a set alpha node with the render layer’s original alpha channel plugged in down stream from vector blur? The reason you see the blur in his face and hair is because those are areas of high contrast. If you pin a texture to his hand you’ll likely see the texture blur too.

#4

Thanks for the tips, Rambobaby, but the compositing is nowhere near as complicated as that. I’m worried I’ve switched some setting accidentally as I’m very much a ‘press-buttons-till-it-works’ Blender user…
The next shot in the sequence illustrates the problem a bit better perhaps:
http://www.martylog.com/comedycuts/lh03.png
The body is spinning around its central axis in this shot but notice how the head mesh is blurred and the body mesh isn’t?
Here’s a rendered mpg: http://www.martylog.com/comedycuts/animtest3.mpg
And here’s the .blend file (version 2.47) for anyone who wouldn’t mind having a peer under the bonnet: http://www.martylog.com/comedycuts/shot03.rar
Any ideas?

#5

Hi,
After playing with your file, it seems you found a bug.
Vector Blur doesn’t appear on meshbased movements with Autosmooth “on”.
After setting Autosmooth " Off" on the Body the vectot blur showed up nicely.
As workaround I would try to use the EdgesplitModifier instead of Autosmooth.
On objectbased Movements this doesn’t happen.
I made a Quick Setup in a New File and it looks as if this is reproducable.

Pat

Edit: I just gave it another try and sadly the EdgesplitModifier produces the same result(noBlur).
And strangley enough after building a new rig and parenting the Autosmooth didn’t give problems.
So this might not be a bug, perhaps something is screwed up only in your rig?
BTW I realised you didn’t apply transforms to your objects and your rig before parenting - this usually would be a good thing todo, because sometimes this could give unwanted results.

Anyway, setting Autosmooth “off” will bring back your VecBlur, but you have a fully smoothed Body then.
Hopefully somebody finds a real solution.

#6

The problem is that vector blur works only as long as vertex counts remain the same across frames. Both Autosmooth and EdgeSplit have the potential to change the vert count (they double the verts along hard edges at render time). You will certainly have to turn off Autosmooth. However, you can keep EdgeSplit – just make sure that it comes before any deformation modifiers in your stack. Then you’ll get blur on everything. GL!

#7

Thanks for the advice - that did the trick! Am looking forward to sharing the finished sequence on here. :slight_smile: