I'm going to be purchasing a license of Rhino v5 along with the T-Splines plug-in, for a customer who regularly requests flowing and/or organic shapes. So I've been doing some playing around with Rhino. One other benefit with Rhino is the fact that it can open and save files in the SolidWorks format, which our CAD/Tooling department uses. I have a MoI file (exported as a STEP file) that I was sending to a CAD operator and I thought that I'd also send a SolidWorks file, to see how it worked for them. When I opened the MoI .3dm file in Rhino, I didn't get what I expected. What appeared to be nice clean CAD data in MoI looked like a very complex (mesh-looking in some areas) file. I've seen some posts on the forum about issues of opening Rhino created files in MoI, but I've opened a fair number of Rhino files in MoI and they seem to have been seamless. What I had in Rhino is what I got in MoI. But, in this case anyway, what I had in MoI isn't what I got when it was opened in Rhino. Is this to be expected or is there a particular method to cleanly opening MoI files in Rhino?

The attached images of a space themed kids mold is an example of what I'm seeing.







Thank-you,

In Rhino you can turn off and on the display of ISO lines, which cleans up the appearance of your objects. Even though you cannot see the iso lines at times does not mean that they are not there.

Ref the attached image from the Rhino training file set.











Just select the object and go to the Properties tab and check the 'Show surface isocurve'. This will make the "extra" complexity appear. I prefer to work with that off most of the time as I am dealing with non-organic surfacing. Is that what you are referring too?

If so, you can also turn on the points of a surface in MoI and where ever you see a line of points that you can edit along a surface is where you would see the ISO curves in Rhino when you have the box checked. Both Moi and Rhino have the same geometry in the files but Rhino shows it differently depending on the selection that you choose to use. In both though, if you show points you should see points to edit in the same spots. I think Rhino shows you the iso lines so if you are sculpting a surface model you can plan ahead better if you are going to need to modify surfaces. I generally do not use them as I am more of a sweep, loft, cut, union solid modeler by trade.

Yes, it was showing the "Surface Isocurves". Once turned off, it looks like the MoI file. It looks like I've got a fair amount of "stuff" to learn, going from MoI to Rhino.

Ah....

You'd think that with Rhino's new release, they would have found a way to anti-alias their curves and iso-curves...
The stair-stepped jagged curves are soooo 1990's!

;-)

Hi Michael, it sounds like you've got it all figured out, that it's just a display issue that you can configure in Rhino. Basically Rhino was originally designed to work with a wireframe display and when you're only drawing wires and no shading at all you need some way to try and see surface shapes and that's why it shows isocurves like that by default. They are just basically curves drawn at some regular intervals along the U and V directions of the surfaces.

There are some various remnants of that original wireframe display orientation still in Rhino, some of which are pretty annoying like the wireframe of selected solid objects showing up on top of everything.

MoI was designed from the ground up to use a shaded display instead.

- Michael

Hi Mike,

> You'd think that with Rhino's new release, they would have found a way to anti-alias
> their curves and iso-curves...

They can do it but unlike MoI they are dependent on the OpenGL video driver to do it for them, and if you have one of the lower cost "gaming" type cards rather than the expensive "workstation" one it may not be available.

One of the nice things about how MoI's graphics engine works is that it does the anti-aliasing itself directly and just sends textured polygon data over to the card for it to display rather than relying on the video driver to do the anti-aliasing instead. That makes MoI's anti-aliased curve display work on any card including "low end" gaming cards.

Often times the low end game-oriented cards actually have the exact same hardware as the "high end workstation" cards, and it's just the drivers for the low end ones have various stuff turned off in them. The more that a program relies on the drivers to do stuff for them, it tends to make that stuff only work on the expensive workstation cards, which can run something like $1000 more in cost than the same "gaming" hardware.

- Michael

"some of which are pretty annoying like the wireframe of selected solid objects showing up on top of everything."

I noticed that. I was hoping I could find a way to turn that off, but it sounds like I'm stuck with it. There are a few things that might come in handy with having a license of Rhino, but my plan is that for the most part, it will only get fired up when there is a need for T-Splines.

I have even more appreciation for MoI, with its clean interface and ease of use, now that I've begun to dabble in Rhino. It's severe information and menu overload. It almost makes me a little queasy.

"You'd think that with Rhino's new release, they would have found a way to anti-alias their curves and iso-curves...
The stair-stepped jagged curves are soooo 1990's!"

There are settings for that in the options. I just left everything default. I can crank it up if I want to later.

Michael,

I figured that with the Open-GL/Direct-X difference... I'm so enamored by the pure-looking lines in MoI even watching the tutorials for Rhino gives me a headache.

And gaming cards are advancing at such a pace that it may become preferable to use more of the 'gaming' end for 3D design applications.

Having the ability to use MoI on older systems has been great for me with my old PC's. I'm even able to use MoI on my tiny XP netbook when sitting on the couch in the living room. My kids are able to watch me try simple objects. Even though it's video is extremely limited, MoI's anti-aliased curves makes even working on a 600-pixel a pleasant experience.

The video drivers for OpenGL in Windows just generally tend to be a lot more problematic than Direct3D drivers. That's actually the main reason why I went with Direct3D for MoI in the first place.

Rhino has become more and more unfriendly to low end systems as time has gone on, there are several video cards that their support staff just flat out says not to use with Rhino: http://wiki.mcneel.com/rhino/videocards

Direct3D drivers can sometimes have bugs in them as well, but because almost all games use Direct3D, those drivers just get a lot more testing and improvement effort put into them so usually the number of driver bugs is way way less with Direct3D.

Then there's also the problem that video card manufacturers seem to intentionally degrade their drivers for their "low end" cards and try to require people doing CAD work with OpenGL to purchase the $1000+ "workstation" type cards instead.

- Michael