Jump to content
AutoDesSys Forums
Sign in to follow this  
jldaureil

Display resolution

Recommended Posts

I derive 3 versions faceted (3 resolutions) from a complex smooth object (initial modeling in solidworks)
(Import in formz gives solid smooth)

The main object is a circular dome.

I wanted to do that in Z8 to get a mesh without a triangle.
But I do not understand exactly how the mesh algorithm works

Here is a synoptic of the parameters used
Z6.7.3 = Max Normal deviation (point density and facets)

TESSEL1.thumb.jpg.d36908acfb4bf72f1316cc8400045432.jpg


When I open the file in Z8
The software creates as many faceting schemes as I have variants
perfect !
It converts the parameter Max Normal deviation to normal angle tolerance
Z6.7.3 = Max Normal deviation (point density and facets)
Z8 = Normal angle tolerance (Surface tolerance and Edge tolerance)

Under Z6 Max Normal deviation is perfectly predictable
for example 15 ° exactly produces a circle of 24 faces (logic 360/15 = 24)

By cons Z8 for Normal angle tolerance at 15 ° I get 36 segments
For 10 ° I have 54 segment instead of 36 under Z6

Do you know why ?

Thanks JL

File

Lien du téléchargement
https://we.tl/t-uEtul5a4bi

 

 

 

Share this post


Link to post
Share on other sites

hi JL,

there are 3 small holes in your hood (for the cables),

they make the faceting a bit complex.

work around : derive the contour and rotate it. so you have best control over the faceting.

vva

Share this post


Link to post
Share on other sites
Posted (edited)

good
This is the way I followed ..
I derived all the faces and then I started to rebuild progressively by rotating the "non-aligned" faces
BUT
for a reason that I do not understand happened to the face on the following image, firstly the derivative face do not produce facets (with 22.5° angle for max normal angle I get 48 segments than 24)  like the others and secondly when I want to rebuild it (nurbz degree 1 in V) facets ares in slight rotation.

TESSEL4.jpg.6c827f87f5f943fb770b66d12afde577.jpg
If I want to be clearer:
I use  two sources that are perfectly aligned (circles 24 segments at 22.5° for Max Normal Angle)
When I perform the tight loft the facets are lightly turned on the resulting nurbz
I still have 24 segments (the first segment perfectly at 90 °on the word grid) but each angle that I can verify by converting the object varies slightly (around 15 °but not exactly 15°) (always with 22.5° for Max normal angle in my exemple)

This curious phenomenon explains why while these geometries are very regular one obtains faces not aligned in direction V (longitude) and thus these series of triangles between the stitched surfaces ...

it's recurrent with parametric geometry in FZ but that's also why converted faceted objects are never as clean as if they were built directly faceted.

Finally, in Z8 if we convert without triangle on fringe  scheme, we obtain shifted grids (which will probably have to be triangulated)

I have the impression that I am confronted here with a fundamental limit of the facet creation algorithm.
(Which explains why   the scheme with triangle one fringe is selected by default)

Edited by jldaureil

Share this post


Link to post
Share on other sites

Hi

I've created a simple file to isolate that question

TESSEL5.thumb.jpg.1cc1c24265ce8a5a1b437b3621422e39.jpg

as you can see faceted objects converted from the smooth nubz loft presents irregularities (pink circles)

(to be compared to the clean faceted version constructed with c-mesh (under Z673))

I do not understand exactly why this occurs...

Ztech, can we have an technical explanation ?

TESSEL6.thumb.jpg.75d6986a238421bfe1c4d70ff9ccdd8a.jpg

TEST smooth.fmz

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×