Rhino 7 - weird shadow artifacts cast by mysterious "ghost" geometry

Hi - I continue to get unexpected shadows on simple model surfaces (rendered viewport, Rhino 7, scene lighting, sun setup for Honolulu) that seem to be cast by mysterious “ghost” (nonexistent) geometry. In the following case I’m getting partial shadows within darkened areas already in shadow, however there is no reason these shadows should occur. If anyone knows how to fix this I’d appreciate it. Note in the image attached that there is no other geometry in the scene, just simple floor plate and wall solids. Making me crazy… Thanks

hi @mwinkelstein pls run _SystemInfo in Rhino, and post back the results.

Sure - here it is. Thanks!

Rhino 7 SR32 2023-8-9 (Rhino 7, 7.32.23221.10241, Git hash:master @ 3d9c816c4cd57561d12d8f53246bce304f314ba2)
License type: Commercial, build 2023-08-09
License details: Stand-Alone

Windows 11 (10.0.22621 SR0.0) or greater (Physical RAM: 32Gb)

Computer platform: LAPTOP - Plugged in [100% battery remaining]

Standard graphics configuration.
Primary display: DisplayLink USB Device (DisplayLink) Memory: 0MB, Driver date: 8-11-2021 (M-D-Y).
> External USB display device with 2 adapter port(s)
- Secondary monitor attached to adapter port #0
- Windows Main Display attached to adapter port #1
Primary OpenGL: NVIDIA GeForce RTX 3070 Ti Laptop GPU (NVidia) Memory: 8GB, Driver date: 10-19-2022 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 517.66
> Integrated accelerated graphics device with 4 adapter port(s)
- Video pass-through to primary display device

Secondary graphics devices.
DisplayLink USB Device (DisplayLink) Memory: 0MB, Driver date: 8-11-2021 (M-D-Y).
> External USB display device with 0 adapter port(s)
- There are no monitors attached to this device. Laptop lid is probably closed
Intel(R) Iris(R) Xe Graphics (Intel) Memory: 1GB, Driver date: 10-26-2022 (M-D-Y).
> Integrated graphics device with 4 adapter port(s)
- There are no monitors attached to this device. Laptop lid is probably closed

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Graphics level being used: OpenGL 4.6 (primary GPU’s maximum)

Anti-alias mode: 8x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High

Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 10-19-2022
Driver Version:
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 8 GB

Rhino plugins that do not ship with Rhino
C:\Program Files\Common Files\McNeel\Rhinoceros\7.0\Plug-ins\Lumion LiveSync for Rhino (839d6175-32d1-4ffe-a0a4-b7fb43cf0ff5)\2021.3.25.899\Lumion\Rhino 7.0\LumionPlugin.rhp “Lumion LiveSync for Rhino”
C:\ProgramData\McNeel\Rhinoceros\7.0\Plug-ins\Datasmith Rhino Exporter (d1fdc795-b334-4933-b680-088119cdc6bb)\DatasmithRhino7.rhp “Datasmith Exporter”

Rhino plugins that ship with Rhino
C:\Program Files\Rhino 7\Plug-ins\Commands.rhp “Commands” 7.32.23221.10241
C:\Program Files\Rhino 7\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 7\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 7.32.23221.10241
C:\Program Files\Rhino 7\Plug-ins\RhinoRender.rhp “Legacy Rhino Render”
C:\Program Files\Rhino 7\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 7.32.23221.10241
C:\Program Files\Rhino 7\Plug-ins\rdk_ui.rhp “Renderer Development Kit UI”
C:\Program Files\Rhino 7\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 7\Plug-ins\RhinoCycles.rhp “RhinoCycles” 7.32.23221.10241
C:\Program Files\Rhino 7\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 7.32.23221.10241
C:\Program Files\Rhino 7\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 7\Plug-ins\Displacement.rhp “Displacement”

Here’s another example from a different model - both incorrect artifact shadows in shadowed areas and also shadows that detach from corners that cast them (a problem I’ve had for years).

Can you post the scene as well? Then I might be able to tweak settings to improve.
In any case, this seems a classic issue with shadow mapping. The larger the scene is, the worse it gets.

Thanks - I’ve tried just about every possible shadow setting (clipping planes, etc.) and find I have this problem with the large model but also the relatively small and simple one posted above. I did, oddly, find I could tweak the Arctic viewport setting to show colors and read similarly to Rendered, and the problem went away. With all settings similar between Arctic and Rendered (lighting, scene, etc.) I found I had to increase the sun intensity to 4x compared to 1x for Rendered, but ended up with a pretty clean result. No idea what is inherently different about Arctic when set to the same settings as Rendered… but the result is far better. Please see following Artic view - no weird shadow artifacts. It seems like there is something with Rendered viewport that is the issue.