Resolution of 3D solids curved

[hanslammerts]

Hi

What variable is controlling this resolution?

I'd also like to know if can be mofified after converting into mass element

See att.

Thanks upfront!

[David_W_Koch]

FACETDEV:  The smaller the number, the more facets.  The number represents the maximum perpendicular distance between the midpoint of a facet and the true curve.

FACETMAX:  Sets a maximum number of facets per curve; if the value of FACETDEV would dictate more facets for a curve, the FACETMAX value will be used.  Valid range is 100 to 10000.

[David_W_Koch]

For Mass Elements, if the Shape is one of the standard shapes, like cylinder, then if you change the value of FACETDEV, the facets will be recalculated and update.  If the Shape is set to Freeform, as it will be if you convert a 3D Solid Cylinder to a Mass Element Cylinder, then the number of facets is frozen at the FACETDEV/FACETMAX settings of the time of conversion and will not change if you change the values.

Also note that there is an eight-facet minimum (for a full circle).

[hanslammerts]

"frozen at the FACETDEV/FACETMAX settings of the time of conversion"

For a freeform object I tried that to change few times, but this value seem to have no influence.

In each case i get around 28 segments for a full circle.

[David_W_Koch · Accepted solution]

I stand corrected.  When converting from a 3D Solid to a Mass Element, the FACETDEV value is not taken into account.  The number of segments does appear to vary with the radius of the curve, but it is not necessarily the same as the FACETDEV and FACETMAX variable settings would produce if drawing a Mass Element directly.  Which means this Autodesk Knowledge Network article is also incorrect:

https://knowledge.autodesk.com/support/autocad-architecture/learn-explore/caas/CloudHelp/cloudhelp/2...   EDIT:  The article is correct.  It is not using the right click context menu to convert a 3D Solid to a Mass Element (MassElementConvert command), but is, instead, using the ConvertMEtoFFME command.  Used on its own, the ConvertMEtoFFME command has similar results to the MassElementConvert command (no relationship to FACETDEV), but when invoked by right clicking on a Mass Element tool of the same shape as the 3D Solid and choosing Apply Tool Properties to > 3D Solid, the FACETDEV setting will be respected.

I may have been using AutoCAD Architecture 2018 last night when I replied, but just checked in 2014, 2016 and 2018 now, and got similar results.

[David_W_Koch · Accepted solution]

And the reason why the Apply Tool Properties to > 3D Solid works with FacetDev is that the resulting Mass Element is not a Freeform shape, but a Cylinder shape, when converting a Cylinder to a Mass Element.  The result also responds to changes in FacetDev.

NOTE:  The above was only tested with Cylinders (3D Solid), converted to Mass Elements.  3D Solids that have been edited and are no longer a "pure" geometric form may behave differently, and result in a Freeform Mass Element.

[Victoria.Studley]

Hi @hanslammerts,

It looks like @David_W_Koch has provided a detailed explanation of how this works. Did his posts help clarify the functionality and point you in the right direction?

If so, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

[hanslammerts]

No it didn't, frankly it just took way to long to get something back on time.

I learned however that working with volume and mass objects i would not do that again.

[suraky]

Ya, it was a nice explanation ... but unfortunately it boils down to  "It works doing X  ... but your 3D Solid has to be a basic useless form, not the thing you've actually modelled".