Challenge 04: Raspberry. This month we are returning once again to basics. Basics however, does not mean easy. There's a lot more going on than initially meets the eye.
Just as last month, there will be a voting panel of industry experts in lookdevelopment - working at Pixar, ILM and Double Negative.
Last month's retroreflector was insanely difficult. People tried through both geometry and BSDF approaches, and I would like to thank all of you who cracked their brains over this challenge. For what it's worth, once again, we've heard some very positive things from top people in the industry. People are watching and it's a fantastic opportunity to show your skillset to them. As was noted in the candy challenge, the paper the raspberry is positioned on will have a big influence on the amount of bounce light, which in turn has a big influence in the way we see the microfibres on the bottom half. So for this challenge, feel free to adjust the backdrop shader to be more like the reference. Good luck everyone!
Reference imagery

.. Pardon me for the slight lens flare in the center of the image.
Getting started
The initial scene setup is very straightforward and only takes 5 minutes. It is important that we standardize scene conditions between contributors, so please make sure that you're not setting up the scene differently.
- Download and extract the .zip package.
- Open or load in the alembic, containing the scene geometry and camera.
- Assign a lambertian material to the floor geometry, assign the checker texture map [tex/checker_floor.tif] to the color slot.
- Repeat step 3 for the macbeth chart [tex/macbeth_chart.tif].
- Create an HDRI light and rotate it in these axis: [51.0, -20.0, 8.0].
The default lighting setup should look like the following.

Please make sure to post renders using this setup. It is allowed to post extra renders using your own light setup. Since the shared light setup is at the core of the challenge, this will be heavily moderated. You've been warned!
What is expected of you?
This month, only one render needs to be submitted. The focus of these challenges is on sharing shading knowledge. Explain the shading setup in as much detail as you can be bothered to do. Think of shaders.xyz as a sort of open source project. Please, also share your scene file if possible. This is not a requirement, but would be very nice. About creating extra geometry - just try to think if it would work in a shading pipeline. If you think it would be practical, go for it.
PLEASE NOTE:
Feel free to post WIPs in this thread.
To tag others in a post, use the "@" symbol.
That's all! The winner gets picked by the admin team on the 1st of July, 2017 and will receive an exclusive SHADERS.XYZ t-shirt (hype!). Don't forget to motivate others by voting for your favorite submission! Good luck everyone!
