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View Full Version : DPont Image Filter questions... using photoreal motion blur and masks...



lardbros
03-17-2014, 03:55 AM
Hey there peeps,
Kind of have an urgent query...

I'll try to explain this as best I can, but I'm struggling a bit as my knowledge of DP's image and pixel filter tools is pretty weak I'm afraid. I've read through the lightwiki on it, and it's helped... but it doesn't cover masking objects as far as I can tell.


Soooo...

I have a scene with a bucket, with particles of sand falling into it... the rest is just black (as I'm comping this onto a 3dsmax render).

I want:
1. The bucket reflection pass, including the particles reflection.
2. A shadow pass of the particles in the bucket.
3. A particle pass on its own

I've got DP Image filter to output a shadow pass, by inverting the shadows and got that going into it's own buffer. I also have a reflection pass of the bucket looking fine.

BUT... the particles pass I have set up, is causing issues.
I am using photoreal motion blur, and where I've told the particles pass to be masked out (within DP image filter), the masking is 'cutting' it out in a really ugly way where they are infront of the bucket (basically aliased and not motion blurred).

It only occurs where the particles are in-front of the bucket.

Is there a proper way to deal with this?? Should I be using the pixel filter one instead and performing some clever jiggery pokery to deal witht he photoreal motion blur?


Thanks VERY much for any help!! :D

Tim

gerardstrada
03-17-2014, 08:56 PM
I'd try with Pixel Filter Node Editor instead.

According to LightWiki tutorial about Pixel Filter Node Editor:

"We can process an image at the pixel level in post-processing or while the render takes place. By depending on our camera settings, this Node Editor can affect the renderer after or before sub-frame operations, that is to say, after or before antialiasing, motion blur, depth of field, etc. have been added to the final image."



Gerardo

lardbros
03-18-2014, 07:22 AM
Sorry Gerardo... I did read through the whole thing, and tried the Pixel Filter, but maybe I'd done something wrong?

It's actually much more straight-forward than I'd initially thought. Thanks very much for your guide in the LightWiki, it has helped me a lot! This is the way I'll do all of my render passes in future... it's remarkably powerful!

gerardstrada
03-18-2014, 06:56 PM
Couldn't really say, Tim. but if DP Mask Object is plugged into GlobalBuffer in Pixel Filter node editor and if samples comes as mBlur passes, the mask takes into account the Motion Blur before subframe operations. But if the passes are set up as AA samples, then motion blur is not taken into account in the mask.

Glad you find DP FNEs useful for multipass rendering. Would like to have the time to complete the article with the Composition, PostFX and Color Grading parts.



Gerardo

lardbros
03-19-2014, 07:26 AM
I just don't think I scutinised my render closely enough... not sure why. :D

Was trying to rush and get the work out I guess.


Thanks again Gerardo! :D

One bit I didn't understand in the wiki article, was the adding of two PFNE's... what is the reason for this, in simple terms? :D

gerardstrada
03-19-2014, 03:45 PM
That's in case you want to add filters to the whole image buffer before sub-frame operations.

i.e.: do you remember X-Dof? it has 2 pixel filter instances. One for gathering data, the other for applying the filter at each AA pass by interacting properly with 3D Motion Blur. We can do the same thing with DP DOF and two PFNE instances and get better DOF quality for each AA/MotionBlur pass, instead of applying the post-DOF once at image level as IFNE. Obviously applying these filter per each AA pass will increment render times.

Sorry if this was not explained in the article, but it's part of the incoming compositing/FX section.



Gerardo