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I currently am trying to blur 7 different objects (1 particle system and a bunch of pictures on planes). I gave each of the objects an ID Mask which leads to their own blur node. However, I'm not sure how to combine these blur nodes. Using a mix node alone seems to make the image "glow" more than blur.

enter image description here

I'm able to use this method to blur one object at a time, allowing me to animate the images at different times, but it doesn't seem to scale just by using a mix node (in all of its configurations). I have no idea if this even scaleable.

Thanks in advance :)

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Instead of using multiple identical Blur nodes and combining the result you should combine the outputs from the ID Mask nodes and use that as te input to a single Blur. You can easily combine them using Math nodes set to Maximum, chaining one to the other until you have combined all ID masks and finally into the single Blur. Since there is only one Blur this should also be considerably more efficient to render.

compositor nodes

To allow the blurring of each object index to be controlled individually you can add some additional maths nodes to multiply each by a variable value (shown in Cyan) as follows :

compositor nodes 2

This can produce the following result :

result

You can keyframe the Value inputs to vary the blur for each ID - with 0.0 for no blur, up to 1.0 for full blur.

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  • $\begingroup$ I'd also add that the math nodes need to have "clamped" checked. $\endgroup$ – Cos Dim Feb 18 '18 at 14:07
  • $\begingroup$ @CosDim good point - certainly needed if using ‘add’ or an operator that could result in values outside the required range - although in this case the Maximum used with the output of ID Mask cannot produce a value outside of range anyway. $\endgroup$ – Rich Sedman Feb 18 '18 at 16:19
  • $\begingroup$ Would I still be able to animate each blur separately with this method? $\endgroup$ – Preposterous Pixel Feb 18 '18 at 19:01
  • $\begingroup$ @PreposterousPixel - not as it stands - you'll need some additional maths nodes for that. See the edit. $\endgroup$ – Rich Sedman Feb 18 '18 at 19:53
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    $\begingroup$ Thanks so much! You literally just saved my promposal :D $\endgroup$ – Preposterous Pixel Feb 18 '18 at 20:26

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