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Weird Streaks

ZBrush Usage Questions
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#1

Hi. I’ve encountered this a couple of times, but haven’t been able to figure out what causes it. Whenever I’ve worked on things like hands and feet, I’ve always noticed these weird streaks/stripes after rendering with BPR. They only show if Shadows is enabled in the Render Properties. I’ve tried turning off some of the other settings that are enabled, but it doesn’t change anything.
The Subdivision levels are currently at 3 and it’s around 2-3 million points. I’ve tried smoothing the mesh down, but that hasn’t fixed it either. And I’ve tried changing the material from a Basic Material. It’s nothing major, but it doesn’t look very clean when doing beauty renders. :-\

hand_render_issue_1
hand_render_issue_2

#2

Hello @DustyShinigami,

This is probably the result of your render settings. When shadows are rendered it doesn’t only render a single shadow–it renders multiple overlapping shadows depending on how many rays are being rendered. Some settings will cause these shadows to separate more. The “streaks” are probably the result of overlapping shadow edges that aren’t being smoothly averaged or blended together.

The main settings to consider are the following (applies to BPR rendering only):

Render> BPR Shadow:

Rays: This controls the number of shadows to be rendered

Angle: This controls how hard edged or soft edged the shadows will be. Higher values result in softer edges shadows, but it does this by causing the shadows to separate more as they are rendered. A high angle value but a low Ray count may result in the edges of the individual shadows being more apparent, resulting in “streaks”. Generally, the higher the Angle value, the higher your Ray count needs to be in order to achieve the best looking results.

Blur: This can help blur the edges for low Ray counts, but there’s a limit to how much this can do. Ideally you want the highest Ray count that still delivers an acceptable render time, and then use a bit of Blur to help blend everything together.

Hope that helps! :slight_smile:

1 Like
#3

Thanks for the advice and explanation. I’ll have a play around with the settings and see if I can reduce it. :slight_smile:

#4

That’s done it. :smiley: I’m not sure how, but I’m guessing the settings were accidentally changed at some point.

Thanks again.

#5

Awesome! It’s possible that no settings were changed, but the relationship of the lighting to the mesh caused it. The farther the light has to travel from the shadow casting mesh to the shadow-receiving surface the more they may separate. Multiple light sources can also complicate the shadow scenario.

Best,

Spyn

#6

Okay. I haven’t set up any lighting since starting the project, but I did adjust the scale in Maya, which made it look smaller in ZBrush compared to how it was originally. I essentially adjusted the height to match that of a female in centimetres, so I’m guessing that could’ve been the cause…?