Rhino 3D: Building a symmetrical free-form product (Part 3)
Posted in 3D Modeling by: adminThis is Part 3 of this Rhino 3D modeling tutorial.
Click here to go back to Part 1
Click here to go back to Part 2
In Part 2, we have already created one half of the model as shown below.
Now, we need to create the other half. We do this by using Mirror. Go to Transform >>> Mirror. Select the surface. Using Osnap End and F8 (Ortho) key, create the other half of the spectacle.
The 2 halves appear to have nicely blended, but they are not. This is because the edge where the 2 halves meet is currently only at Positional-level Continuity. At this continuity level, the 2 surfaces will not appear seamless. We need to ensure at least Tangent-level Continuity for that edge, otherwise for actual production and manufacturing, the part may show an unacceptable line where the 2 halves meet.
To resolve that, we can use Match Surface to modify the continuity to Tangency-level.
To do that, go to Surface Tools >>> Match Surface. When prompted, select the 2 adjacent edges of the 2 halves. From the Match Surface dialog box, select Tangency or Curvature (depending on your continuity requirement). Next select, Average Surfaces and Refine Match. The adjacent border of the surfaces should be tangent to each other now.
After this, one should evaluate the surface continuity. There are several ways to do this. The common way is to use the Environmental Map or Zebra to visually assess the smoothness and continuity. To evaluate visually using Environment map, select the surfaces, go to Analyze>>> Environmental Map. It is as illustrated below.
That is all for the tutorial. As mention earlier, this method of using Curve from 2 Views with Match surface can be applied for symmetrical modeling of products of other forms as well.
The same method can also be applied to Alias or Autodesk StudioTools. However, in the case of StudioTools, one can simply select Implied Tangent (for the adjacent border) when using Rail Surface and need not go through an additional surface matching process.
October 24th, 2008 at 3:10 am
[...] >>> Click here to go to Part 3 [...]
October 25th, 2008 at 3:42 pm
Hello gerald! I’m Zhenhao! remember me not!
Your student! batch 18!
Damn shocking to find your blog here!
hahaha
October 25th, 2008 at 3:48 pm
Hi Zhenhao,
Ha ha… Small world hor…
heh heh…
October 28th, 2008 at 5:55 pm
Hi there. Why not use Symmetry instead of Mirror+MatchSurface, which was the Rhino 3.0 way of doing things? – I like your tutorial anyway, but personaly I find the Symmetry WithHistoryEnabled much nicer, since you can actually change all the shapes, while actively seeing the result “live” (without deleting and starting over). That was the reason why McNeel introduced “Symmetry” anyway. Kind regards and respect. Tim Elkær
October 29th, 2008 at 12:54 am
Hi Tim,
Thanks so much for pointing out the new feature of version 4. Personally, I am quite new to Rhino version 4. For this tutorial, I am using the evaluation/trial version of Rhino 4.
At the workplace, I use Rhino 3 and at home, I am still using Rhino 1. LOL… Rhino is so good that version 1 still serve very well.
I guess, there are still quite a number of people using the older versions. So in a way, the tutorial was written for compatibility with the older versions of Rhino.
Regards and thanks.
Sim
February 6th, 2010 at 10:21 pm
Ok, here’s a work around:
If I loft the two generation curves, then dupedge, and use these as the rails (with handle curves closed on both ends) it works. Would love it if I knew why I had to do that extra step – which changed the curves anyway (without ‘do not simplify’ checked’; but the precision doesn’t matter at this point…
February 6th, 2010 at 10:28 pm
Mirror vs. Symmetry –
I was also surprised this tutorial led to ‘mirror’; but I can’t get Symmetry to work (which is what I was searching for when I found the tutorial)…
‘Symmetry’ only gives me options to ’select curve edge or surface edge’, and I don’t see ‘withhistoryenabled’; only ‘record history’ on the buttons below…there must be a way to select a whole group of objects? Without that and history, it’s not even as good as mirror…
February 7th, 2010 at 5:00 pm
I think, to use Symmetry (with editable surface), the ‘Record History’ must be enabled first before building the first half of the object.