Tuesday, January 21, 2014

Solid Angle Arnold AOVs & Object IDs

So after yesterday I was left with a taste for more figuring out what this render engine is actually capable of outputting as I really want to get some animated batches in Nuke for editing. I am intentionally not following any start to finish tutorials since I want to figure out what can go wrong and what other hidden things are tucked away in corners I wouldn't check otherwise. I feel I'd circumvent problems that could help me understand why certain renders look better than others.

I rebuilt the shaders for the Red Skull model to have a light subsurface scatter. This turned out to clamp the brightness of the rim shader but really - that's okay since they were a little bit too present in the render I had made previously. I also created a ObjectID input for the shaders since I want to be able to edit the values of the background and foreground individually. It's really quite simple to do this since Solid Angle provides AiUtility nodes that already have the attribute in a drop down menu. All you have to do is turn on ObjectID in the AOVs tab for your render settings and drag the AiUtility node to it's corresponding input of the rim shader shader engine. Image below.

Small shader with ObjectID.

After that I spent a few hours figuring out how to render a batch set to a single EXR file but couldn't find the option. Turns out it isn't in the render settings for the Arnold renderer but is presented when you select the driver running your custom AOVs. A simple check box under the header 'Advanced Output' called 'Merge AOVs' turns it on and off. I wish this setting was in the render settings. Would have saved some time.

Merge AOVs.

While writing this blog post I've been rendering a 2k image with around 18 different AOVs which I will now have the pleasure to edit in Nuke. For tomorrow I'm planning to create a small animation in the same scene to see how to use sequences in Nuke with this many channels. Hopefully my trusty laptop will run all of this; otherwise I will have to turn to the renderfarm at my college. I'm not sure if I have enough HDD space to render this many channels (even if I don't need this many) for a few second animation. The .exr output I have right now is already 720MB... I might have enough space for one second. Below is a picture of ObjectID working in Nuke.

ObjectID working

Kind regards,

ps. If I get a good result I'll post it together with tomorrow's update... in case I'll make such an update... No promises!

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