STP import results in bad object (bug)

Rhino Rhino for Windows
,
1

I have this model:
2024-12-12_NotAsSTP.3dm (348.0 KB)

When I export it to STP

image
image364Ă—240 4.77 KB

2024-12-12_NotAsSTP.stp (268.7 KB)

and then OPEN the STP in Rhino, I get a bad object:

image
image991Ă—702 93.1 KB

When I OPEN the STP in V5, the geometry is fine, no bad objects.
In V7 there is the bad object as well.

Rhino 8 SR15 2024-12-10 (Rhino 8, 8.15.24345.18001, Git hash:master @ 73c926a1bdc2630d5d19ed4299fac5f03bf2455b)
License type: Commercial, build 2024-12-10
License details: Cloud Zoo

Windows 11 (10.0.26100 SR0.0) or greater (Physical RAM: 32GB)
.NET Framework 4.8.9290.0

Computer platform: DESKTOP

Standard graphics configuration.
Primary display and OpenGL: NVIDIA GeForce RTX 2070 (NVidia) Memory: 8GB, Driver date: 8-14-2024 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 560.94
> Accelerated graphics device with 4 adapter port(s)
- Windows Main Display attached to adapter port 0

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: 8-14-2024
Driver Version: 32.0.15.6094
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\RhinoNestRhino6\System\RhinoNest.rhp “RhinoNest” 4.6.18354.2

Rhino plugins that ship with Rhino
C:\Program Files\Rhino 8\Plug-ins\SolidTools.rhp “SolidTools”
C:\Program Files\Rhino 8\Plug-ins\Commands.rhp “Commands” 8.15.24345.18001
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” 8.15.24345.18001
C:\Program Files\Rhino 8\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 8.15.24345.18001
C:\Program Files\Rhino 8\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 8\Plug-ins\MeshCommands.rhp “MeshCommands” 8.15.24345.18001
C:\Program Files\Rhino 8\Plug-ins\export_STEP.rhp “STEP Export”
C:\Program Files\Rhino 8\Plug-ins\RhinoCycles.rhp “RhinoCycles” 8.15.24345.18001
C:\Program Files\Rhino 8\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 8.15.24345.18001
C:\Program Files\Rhino 8\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 8\Plug-ins\Displacement.rhp “Displacement”
C:\Program Files\Rhino 8\Plug-ins\SectionTools.rhp “SectionTools”

2

Hi @Charles,

I’ve logged the issue so a developer can investigate.

https://mcneel.myjetbrains.com/youtrack/issue/RH-85171

– Dale

3

Release target 9.x?
It’s about a bug, a regression from V5, and not about a new feature…?

4

Charles, I don’t think this is a bug. Please take a look at your input curves.

image
image2192Ă—1070 196 KB

There are at least two places where you have multiple control points on top of each other. Most of the +/- 90° corners have multiple control points. You can also see the result of this in the surface shading.

I extracted the bottom edge curve and ran FitCrv. I untrimmed and retrimmed the bottom surface and offset the trimmed surface. Now I know my rebuilt polysurface isn’t exactly like your object but the main thing is that there are no more coincident control points.

image
image1876Ă—1478 273 KB

My *.stp export import was succesful.

2024-12-12_NotAsSTP_mrtn.3dm (820.7 KB)

test.stp (227.3 KB)

5

Martin, thanks for your effort, I know the model has flaws.
I know how to handle them.

One simple solution is to Explode the original, ShrinkTrimmedSrf, and Join.
Good enough, and then there is no STP problem.

But I wanted to point out a STP import problem…
V5 imports fine.

6

Ok, you didn’t mention that in your OP.

:zipper_mouth_face: flawed object exported as *.stp imports as bad object…

7

Even if the geometry is not ideal:

When we SelBadObjects in the original 3dm file, there is none.
STP export should go ok.

One object gets bad when we import the STP in V8.

Other software doesn’t show this problem, and even Rhino V5 doesn’t show it.
From the same exported STP.

I assume there is something with the STP import in V7/8.
Just wanted to report.

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