When I try to loose project the blue lines onto the grey mesh, most of them fail to project. When I try to project only single one, this is the error:
Select surfaces, polysurfaces, SubDs and meshes to project onto. Press Enter when done ( Loose=Yes DeleteInput=Yes OutputLayer=Input Direction=CPlaneZ )
Projecting… Press Esc to cancel The projection missed the selected objects.
Windows 10 (10.0.19045 SR0.0) or greater (Physical RAM: 48GB)
.NET 8.0.14
Computer platform: DESKTOP
Standard graphics configuration.
Primary display and OpenGL: Radeon RX Vega (AMD) Memory: 8GB, Driver date: 7-1-2025 (M-D-Y). OpenGL Ver: 4.6.0 Compatibility Profile Context 25.8.1.250617
> Accelerated graphics device with 7 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: 8x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High
Vendor Name: ATI Technologies Inc.
Render version: 4.6
Shading Language: 4.60
Driver Date: 7-1-2025
Driver Version: 31.0.21923.11000
Maximum Texture size: 16384 x 16384
Z-Buffer depth: 24 bits
Maximum Viewport size: 16384 x 16384
Total Video Memory: 8119 MB
Rhino plugins that do not ship with Rhino
C:\ProgramData\McNeel\Rhinoceros\8.0\Plug-ins\Datasmith Rhino Exporter (d1fdc795-b334-4933-b680-088119cdc6bb)\DatasmithRhino8.rhp “Datasmith Exporter” 5.5.4.0
Projecting onto polygonal surfaces is unreliable (and generally bad practice).
This is due to tolerance issues at edges and corners. It’s better to create a clean surface that deviates only slightly from your mesh and use that as the projection base. Polygons might also contain errors, so it’s useful to simplify the shape. On the construction side, you also “modify” the surface before putting anything onto it. Polygons are for reference, not for modelling.
Why would there be a difference between projecting in an orthogonal versus perpsective view when Direction=CPlaneZ assuming the the Cplane is the same? I assume the view direction is not or at least should not be involved with Projection unless Direction=View.
The problem is caused by the combination of Loose=Yes and the mesh as the target.
With the mesh as the target Project with Loose=No works as expected in both the perspective and top viewports. However with Loose=Yes the results are the same as @omichalek shows above.
I used ToNURBS to convert the mesh to an open polysurface with 20678 surfaces. (Note, the use of ToNURBS in this way is NOT recommended as a normal part of workflow.) With the polysurface as the target Project with both Loose=Yes and Loose=No works as expected.
This should be submitted for the developers to look at.
You might submit a bug report the next time you run into Project in a perspective viewport with other than Direction=View not working correctly while working correctly in the top viewport. I don’t recall ever encountering such a problem.
On the other hand if the Direction option is set to View I would expect different results.
