Need docs for Save As Mesh > Refinement Settings

[graham.wideman]

The Save As Mesh dialog has Refinement Settings, specifically:

• Surface Deviation
• Normal Deviation
• Maximum Edge Length
• Aspect Ratio.

If there is a doc or help info on what these actually do, please point me to it. Nearest I could find were:

• https://help.autodesk.com/view/fusion360/ENU/?guid=MESH-TESSELLATE
• https://help.autodesk.com/view/fusion360/ENU/?guid=SLD-3D-PRINT

... neither of which actual pertain to this dialog specifically, nor explain what the impact of these settings might be.  This next link

• https://help.autodesk.com/view/fusion360/ENU/?guid=SIM-MESH-QUALITY

... at least explains "Aspect Ratio", stating that the ideal mesh aspect ratio is 1.0.  Meanwhile, in the Save As Mesh dialog, the Refinement Preset always sets Aspect Ratio to 21.50. Presumably these are not the same variable. (In any case, each triangle in the mesh can't have the same aspect ratio, because it has to adapt to the surface it's modelling. So a single number setting here is enigmatic to say the least.)

So, could we please see a doc explaining the Save As Mesh dialog settings?

Thanks.

[Drewpan]

Hi,

Unless there is something in the Self Paced Learning you might have to look in a few other places. Have you

searched the AutoDesk University tutorials? How about the Fusion YouTube Channel? Failing those, if the forum

cannot help you then you might have to pop your Google Goggles on.

Cheers

Andrew

[graham.wideman]

• Autodesk University search, selecting Fusion as the Product, and "Save As Mesh" as the search term came up with five unrelated or business-oriented videos that have basically no chance of containing the specific details, and I'm not going to watch 5 hours of video just to confirm that.
   
• Autodesk Fusion YT channel has many many videos, and a variety of searches for terms relating the Save as Mesh and subsidiary terms found nothing relevant to my question.

Now obviously google is a good suggestion, but as a normal person I have, of course, thought of that already, which is how I found the articles I already referenced.

This information should either be in

• the dialog's popup hints (it is not) or
• in the help for this dialog: closest thing is https://help.autodesk.com/view/fusion360/ENU/?guid=MESH-EXPORT-TOOLS  but no mention of the actual settings.
• the dialog's "i" information box, which leads to: https://help.autodesk.com/view/fusion360/ENU/?guid=SLD-3D-PRINT, where we find:

  • "Expand the Refinement Settings and select the level of Refinement. Optionally, adjust the individual settings:

    • Surface Deviation: Specify maximum distance between the surface of the original body and the surface of the mesh body.
    • Normal Deviation: Specify maximum angle between the normal vectors of each face on the mesh body.
    • Maximum Edge Length: Specify maximum length of any face edge on the mesh body.
    • Aspect Ratio: Specify ratio between the height and width of each face on the mesh body."

 Surface Deviation and Max Edge Length are fairly self-evident, and the description here is helpful. Normal Deviation becomes clearer with the explanation that "Normal" refers to the normal vectors. Though the implications of any particular angle are not discussed.

But the explanation of Aspect Ratio simply describes what that term normally means, and it can't apply to an STL mesh where the many triangles have different aspect ratios in order to conform to a surface, and the value set by the built-in presets is 21.5, which is so extreme that it's highly unlikely as an aspect ratio.

[graham.wideman]

I think I'm going to repost this as a more focused question about Aspect Ratio only.

https://forums.autodesk.com/t5/fusion-design-validate-document/meaning-of-aspect-ratio-in-the-save-a...

[jeff_strater]

I can help here.  It all has to do with the size and shape of the resulting triangles in the mesh

• Surface Deviation - maximum distance of the triangle from the actual surface it is representing
• Normal Deviation - maximum deviation of the surface normal of the triangle from any point on the part of the surface it represents
• Maximum Edge Length - the maximum length of any edge on any triangle in the mesh
• Aspect Ratio. - @HughesTooling explained this pretty well in the other thread - the ratio of sides of the triangle.  A way to avoid long, thin triangles

[graham.wideman]

Hi @jeff_strater .

I've now seen the reply in the other thread, and I think we're converging on the conclusion that the Aspect Ratio setting is misnamed and improperly described in the docs.

It is not (can cannot be) the aspect ratio applied to each triangle. Rather, it is probably the Maximum Aspect Ratio that the meshing algorithm is allowed to apply.  And as @HughesTooling described, the rationale would be that geometry of overly long skinny triangles can cause problems in subsequent processes.