[BUG R8] AM62 “Delete Mapping” creates UVmapping artifacts-NOT Rhino9WIP

Rendering
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Bug: “Delete Mapping” creates UV mapping artifacts always using this file (Rhino 8) – Not reproducible in Rhino 9 WIP

AM62

Version (affected)
Rhino 8 SR28 — 8.28.26041.11001 (2026-02-10)

Version (not affected)
Rhino 9 WIP — working correctly — 9.0.26055.12305 (2026-02-24)

File attached (in the next reply)
AM62 UV mapping-mesh artifacts1.3dm

Summary

In Rhino 8, pressing the Delete Mapping button in the Texture Mapping panel always generates unexpected UV artifacts using the enclosed file.

After deleting the mapping, reopening the UV Editor shows diagonal yellow UV edges/lines, artifacts that should not exist.

The issue does not occur in Rhino 9 WIP 9.0.26055.12305 (2026-02-24) when copying and pasting the same 3d geometry or loading the file.

This report isolates the issue in a simple mesh case, but the behavior frequently appears in larger production models and becomes difficult to clean up.

As a workaround, a manual cleanup is needed inside the UV editor, and pressing the [ok] button several times for each individual surface.

Steps to Reproduce

  1. Load file: AM62 UV mapping-mesh artifacts1.3dm

  2. Open UV Editor

  3. Close the UV Editor.

  4. In the Texture Mapping tab, press [Delete Mapping].

    image
    image592×214 28.6 KB

  5. Reopen the UV Editor.

Actual Result

image
image1564×1287 187 KB

  • Unexpected yellow UV edges/lines appear.

  • UV mapping mesh is corrupted or partially retained.

  • The mapping is not cleanly reset.

Expected Result

  • A complet clean up of the UV mapping mesh state.

  • No leftover UV mesh artifacts.

  • Behavior consistent with Rhino 9 WIP (which works correctly).

Workaround

  1. Open UV Editor.

  2. Select all UV mapping meshes manually.

  3. Delete them.

  4. Press OK several times: if you have 100 surfaces, you will click the OK button 100 times.

  5. Close UV Editor.

  6. Press [Delete Mapping] one more time.

After this sequence, the mapping resets correctly.

Environment

Rhino 8 SR28 (8.28.26041.11001)
Windows 11 (10.0.26200)
.NET 8.0.14

GPU: NVIDIA GeForce RTX 5090 — Driver 591.74 (12-30-2025)
OpenGL 4.6
64GB RAM

Additional plugin installed:

  • SubstanceImporter 2.0.7

(All other plugins are default Rhino 8 components.)

Notes

  • The bug appears to be related to UV mapping mesh cleanup after Delete Mapping.

  • It seems Rhino 8 does not fully clear the internal UV mesh data.

  • Rhino 9 WIP appears to handle this correctly in this case, but not in all cases.

System Information

Rhino 8 SR28 2026-2-10 (Rhino 8, 8.28.26041.11001, Git hash:master @ b7874a05a6982d0419fcc4f6009b510b48a09cb3)
License type: Commercial, build 2026-02-10
License details: Cloud Zoo

Windows 11 (10.0.26200 SR0.0) or greater (Physical RAM: 64GB)
.NET 8.0.14

Computer platform: DESKTOP

Standard graphics configuration.
Primary display and OpenGL: NVIDIA GeForce RTX 5090 (NVidia) Memory: 32GB, Driver date: 12-30-2025 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 591.74

Accelerated graphics device with 4 adapter port(s)

  • Secondary monitor attached to adapter port 0
  • Windows Main Display attached to adapter port 1

Secondary graphics devices.
Intel(R) UHD Graphics 770 (Intel) Memory: 2GB, Driver date: 10-18-2024 (M-D-Y).

Integrated graphics device with 4 adapter port(s)

  • There are no monitors attached to this device!

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
GPU Tessellation is: 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: 12-30-2025
Driver Version: 32.0.15.9174
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 32607 MB

Rhino plugins that do not ship with Rhino
C:\Users\a_mat\AppData\Roaming\McNeel\Rhinoceros\packages\8.0\SubstanceImporter\2.0.7\Substance.Win.rhp “SubstanceImporter” 2.0.7.0

Rhino plugins that ship with Rhino
C:\Program Files\Rhino 8\Plug-ins\Commands.rhp “Commands” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\WebBrowser.rhp “WebBrowser”
C:\Program Files\Rhino 8\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 8\Plug-ins\RhinoScript.rhp “RhinoScript”
C:\Program Files\Rhino 8\Plug-ins\IdleProcessor.rhp “IdleProcessor”
C:\Program Files\Rhino 8\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 8\Plug-ins\MeshCommands.rhp “MeshCommands” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\RhinoCycles.rhp “RhinoCycles” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 8.28.26041.11001
C:\Program Files\Rhino 8\Plug-ins\Displacement.rhp “Displacement”
C:\Program Files\Rhino 8\Plug-ins\SectionTools.rhp “SectionTools”

2

Enclosed file

AM61UVmappingFlippedSurfaces1.3dm (14.6 MB)