[BUG R9] AM63 Unwrap does not split polysurface along seams,remain welded

Rendering
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1

image
image1570×977 354 KB

AM63 2026-02-27T03:00:00Z

Product / Version

  • Rhino 9 SR0 (Rhino WIP) — 9.0.26055.12305 (2026-02-24)

  • Git hash: master @ 9ee31a3c2831f65aa872a3f62dc11054381a7f68

Platform

  • Windows 11 (10.0.26200 SR0.0)

  • .NET 9.0.1

  • OpenGL display mode (Standard graphics configuration)

File

  • AM63 UV mapping cant divide it 2 (attached)

AM63 UV mapping cant divide it 2.3dm (17.6 MB)

Summary

Always, when unwrapping this enclosed polysurface using custom Unwrap and selecting all the seams, the UV mapping mesh does not split along the seams. In the UV Editor, the faces remain attached/welded as if the seams were ignored.

Steps to Reproduce

  1. Open the file: “AM63 UV mapping cant divide it 2” in Rhino 8 or 9

  2. Select the polysurface.

  3. (Optional) Run Delete UV mapping (not required, but tested).

  4. Run Unwrap and choose a custom unwrap.

    image
    image537×108 7.69 KB

  5. Select all the seams:

    • Drag-select seams (top-left → bottom-right), or

    • Select seams one by one.

  6. Open the UV Editor.

Actual Result

  • The UV mapping mesh islands are not divided along the selected seams.

  • As shown in the initial screenshot, surfaces remain stuck together (attached/welded) despite seam selection.

Expected Result

  • Seams should cut/split the polysurface into separate UV mapping mesh islands.

  • Each surface/face should have its own corresponding UV surface island defined by the seam boundaries.

System Info (as reported)

Rhino 9 SR0 2026-2-17 (Rhino WIP, 9.0.26055.12305)
License: Commercial (Cloud Zoo), expires 2026-04-10

Hardware / Graphics

  • NVIDIA GeForce RTX 5090, 32 GB, Driver 591.74 (12-30-2025)
    OpenGL 4.6.0 NVIDIA

  • Intel UHD Graphics 770 (no monitors attached)

OpenGL Settings

  • Safe mode Off, Hardware acceleration On, GPU tessellation On

  • AA 4x, Max texture 32768², Z-buffer 24-bit, VRAM ~32607 MB

Notes / What I tried

  • Same behavior in Rhino 8, whether seams are selected by drag-selection or manually one-by-one.

  • The “Delete UV mapping” step does not seem to change the outcome (the issue persists).

  • No workaround possible, ExtractSrf → Unwrap per face → Rejoin is not possible because Rejoining loses the UV mapping.

  • ExtractSrf → Unwrap per face is not possible because a solid or a polysurface is needed.

Workaround

  • Extract the rendering mesh ! _ExtractRenderMesh and unwrap it in Rhino or outside. You will have a mesh instead of a polysurface.

System Information…

Rhino 9 SR0 2026-2-24 (Rhino WIP, 9.0.26055.12305, Git hash:master @ 9ee31a3c2831f65aa872a3f62dc11054381a7f68)
License type: Commercial, build 2026-02-24
License details: Cloud Zoo
Expires on: 2026-04-10

Windows 11 (10.0.26200 SR0.0) or greater (Physical RAM: 64GB)
.NET 9.0.1

Computer platform: DESKTOP

Standard graphics configuration using OpenGL
Primary display: NVIDIA GeForce RTX 5090 (NVidia) Memory: 32GB, Driver date: 12-30-2025 (M-D-Y). OpenGL(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: 4x
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

OpenBLAS: OpenBLAS 0.3.30 DYNAMIC_ARCH NO_AFFINITY Haswell MAX_THREADS=64.

Rhino plugins that do not ship with Rhino

Rhino plugins that ship with Rhino
C:\Program Files\Rhino 9 WIP\Plug-ins\Commands.rhp “Commands” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 9 WIP\Plug-ins\UpdatesAndStatistics\UpdatesAndStatistics.rhp “UpdatesAndStatistics” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 9 WIP\Plug-ins\MeshCommands.rhp “MeshCommands” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoCycles.rhp “RhinoCycles” 9.0.26055.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 9 WIP\Plug-ins\Displacement.rhp “Displacement”
C:\Program Files\Rhino 9 WIP\Plug-ins\SectionTools.rhp “SectionTools”