Hi guys,
can someone help me please. How can I get the blue part glowing with the glare node?
The blue part (emission shader) is driven by an alpha texture.
Any help is very much appreciated
Thanks
Pete
Thanks. Thatâs pretty easy. But it only works if you have only one emissive material. If there ist a second one it will be be âglowedâ (is this a real word?) as well as the first material.
It may not be ideal but you could model the blue part and give it an emission shader. Then, assign it an object pass index to isolate it in the compositor and give it the glare node.
You can use the Object or Material ID to get a clean mask of one or multiple Objects. If you want only the emissive parts of the mask youâll have to multiply the ID Mask with the Emission pass in the Compositor. This way you can keep your model in one piece.
Thanks Cubezz, that sounds like a good idea. I will give that a try.
Actually I found a way: I put the emissive parts to another layer too, rendered this layer without the evironment an lighting (itâs quiet like âmasking the emission passâ) and then did the compositing on it. After that I multiplied the glow-layer with the original renderlayer. This worked quiet well because I rendered the glow-layer with one sample only
Now, thereâs one thing to be aware of when you are using effects like this: âobject-IDs donât know about effects.â Particularly effects, like blur or glow, that affect surrounding pixels. Object-IDs also know nothing of things like (anti-)aliasing. They are literally ânothing more and nothing lessâ than a pixel-by-pixel identification of which object was closest to the camera at that location.
Therefore, shoot a test-render to a MultiLayer OpenEXR file with all the goodies turned-on, including Object-ID. Then, say in a separate Blend-file, use that file as the input to a node in the compositor â verify that all of the expected data-channels are present â then use various Viewers to examine one or more of these data-channels. Set up simple experimental compositing setups. (All the data has been captured into the file ahead of time, so it wonât take any âtime.â) Test your assumptions of what the data will look like and how it can best be manipulated âin post.â Fifteen minutes of hands-on futzing-around will answer more questions than any forum-post ever could.
Note: I specify âMultiLayer OpenEXRâ because this file-format is specifically designed to capture multiple layers of high-resolution digital data, exactly as the renderer produced it. It was engineered â by Industrial Light & Magic with a little help from the Blender Foundation â for this purpose. âThe data, the whole data, and nothing but the data.â
I have a couple of cents to the discussion. Sometimes when you fiddle with results of âID Maskâ node as say alpha for some blending, itâs a good idea to use âDilate/erodeâ node to fix very rough masks.
The biggest point to be made is that you have to do all of the effects-processing âin post,â not in the renders.
An id-mask canât be âblurred.â Each pixel has one, and only one, object-ID associated with it. It isnât anti-aliased. Therefore, the pixel-value data that you associate with the object-ID must be a pixel thatâs getting its color information only from that one object, not from surrounding areas as would be the case with in-render blur. Itâs simply âthe nature of the data that you have at your disposal.â (It doesnât act like an optical mask âŚ) If youâre careful to observe this, there are many filters that you can use in post. But donât even try to match in-post whatâs already been done in-camera because itâll never look right.
Whats with the absolutes? It is wise to do things in post that are faster, more controllable or otherwise better to do in post. What is not, do in renders. What is an effect anyway? Why is lens bloom more of an effect than light bleed from GI?
It can. ID channel is not a mask. Once a specific mask is extracted from ID channel, one can blur blur it to his pleasure.