Crystal render is flat, without sparkle

[maja.divjakW2VMQ]

Hi there,

I am trying to render a crystal to which I have applied the Arnold diamond shader. In the attached image, you can see the render does not sparkle at all and instead appears flat, like it has a toon shader applied.

I have a skyDome light to which I have applied a HDRI image. The skyDome attributes are at default.

I've created a grey torus backdrop surrounding the crystal (which will be spinning rotating in space) and I've applied an Arnold standardSurface shader to it, coloured the base white, adjusted specular roughness to about 0.3 and specular weight to about 0.4 and under transmission > emission > advanced, turned on caustics. I've turned off primary visibility of the torus in the render.

I adjusted the camera aperture size under the Arnold rollout to 0

In the render settings window, I have camera samples set to 5 and increasing specular, SSS or transmission makes no difference to the render

Turning opaque on and off in the Arnold rollout on the crystalMeshShape also makes no difference to the render.

If anyone could please advise what I'm doing wrong and why the render appears so flat and unattractive, I would greatly appreciate it.

Thanks so much and best wishes,

Maja

[lee_griggs]

Have you tried bloom in the imager.lens_effect?

https://docs.arnoldrenderer.com/display/A5AFMUG/Bloom

Which HDR map are you using? Rendering diamonds requires a HDR map with a lot of contrast and detail to get interesting reflections and refractions. A photography studio HDR map would be ideal.

Also what do your ray_depth settings look like? You may need to increase the number of specular and transmission rays to get more bounces in the diamond.

https://docs.arnoldrenderer.com/display/A5AFMUG/Arnold+for+Maya+User+Guide

[maja.divjakW2VMQ]

Thanks Lee,

I'll give those a try and let you know how I go.

[maja.divjakW2VMQ]

Hi Lee,

Have tried your suggestions- using a more complex HDRI and adding bloom. These had most effect. The ray depth settings had little to no effect. I also played with the diamond shader itself, adding some blue to the specular colour and almost white to the transmission colour. I also turned off the torus, which was blocking a lot of the light from the skyDome. Not looking photo real, but way better than it was. See attached. If you have any further suggestions, they will be gratefully received.

Thanks so much and best wishes,

Maja

[lee_griggs]

Getting there. Did you try a photo studio HDR map? I found something like this one works well with diamonds.

[maja.divjakW2VMQ]

Hi Lee,

I actually bought a map specifically for rendering jewels, but they are yet to send it to me, so I've been using a landscape with trees, sunlight and a park bench. See attached. Are you able to share the map you posted above please.

Thanks so much and best wishes,

Maja

[lee_griggs]

Here, try some of these.

https://www.hdrihaven.com/hdris/?c=studio

[maja.divjakW2VMQ]

Thanks Lee,

I tried this one:

And the result is:

Almost there. Any further suggestions gratefully accepted.

Thanks so much for your help and best wishes,

Maja

[maja.divjakW2VMQ]

Sorry, result didn't upload:

[lee_griggs]

Are you using ACES color management? It doesn't look like the HDR map is set correctly to RAW?

https://docs.arnoldrenderer.com/display/A5AFMUG/ACES+Workflow

[maja.divjakW2VMQ]

Hi Lee,

No, I'm not using ACEScg. Going to try this for my next big project. My Colour Management prefs are set to scene-linear DCI-P3 with view transform set to sRGB Gamma, as per the attached image. In render settings, the colour space is set to Use Output Transform. The HDRI image is set to RAW. I've tried to read up on colour management, but it's complex and confusing. I'm not sure these settings are correct? If you could please advise, that would be great.

Thanks so much,

Maja

[lee_griggs]

Are you using Maya 2022? If so, the default ACES settings should be fine. Color management setup can be found here:

https://help.autodesk.com/view/MAYAUL/2022/ENU/?guid=GUID-A5A2B5C8-7992-41E3-8482-9DD86EC89717

[maja.divjakW2VMQ]

Hi Lee,No, using Maya 2020. I believe I have to define the colour prefs myself? Hope I've managed to do it correctly...