I imported one of my models into Powermill and noticed that several of the surfaces were not facing upwards. How does one reverse the surfaces?

I don't know anything about Powermill, but it sounds like your normals are backwards. Most 3D programs have a feature that lest you flip them.

Select the surface in MoI and enter the non-UI command: "Flip"

Hi bigseb - surely if Powermill is sensitive to needing surface normals pointing in a particular way it must have some tool in there for flipping them.

For doing it in MoI the Flip command that Mike mentioned has some more details here:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#flip

Also if you make your object into a fully joined solid instead of just an open surface it will then automatically get the surface normals pointing to the outside of the solid volume.

- Michael

Powermill can reverse them but it looks shoddy when the model is opened up. I can't give models like that to clients.

I worked on Rhino for years and that had the function to flip surfaces, you could also set the backfaces to have a specific colour so it would be immediately recognizable. I was hoping MoI could do that too.

Also, sometimes I don't need to make a joined solid, I only pass on surfaces. There's no way of telling what's what...

Hi bigseb - MoI does not have a backface display command yet, but that is something that I do want to add in the future.

There is a function to flip surfaces in MoI though, some info on that here:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#flip

I don't understand about the part about flipping them in Powermill giving shoddy results - doesn't flipping it in Powermill produce a flipped surface the same as if you were to flip it in MoI? Could you maybe describe why flipping it in Powermill is different than flipping it in MoI or Rhino?

- Michael

Its not that it doesn't work, it just looks bad if I give a client a model where some surfaces are the right way up and some are reversed. The model works fine either way but it looks untidy.

The upper right corner has a properties area. When you select an object, it will display some info about the object.. "Solid, Surface, joined surface, curve, closed curve, etc...."

Hi bigseb,

> Its not that it doesn't work, it just looks bad if I give
> a client a model where some surfaces are the right
> way up and some are reversed.

I see - but how was it that you noticed in Powermill that some surfaces were reversed in the first place, does it show some kind of indicator or coloring of the object side in there? If so then you could use it to do the direction tuning.

Another thing that will help a lot is if you join any surfaces that are just sitting next to each other together so that they are connected by a shared edge instead of just being totally separate surfaces just happening to sit adjacent to one another.

When they're actually joined the whole joined thing will have a common positive surface normal side which still may need to be flipped but you'll only have to flip a big piece instead of a whole lot of little separate pieces.

So it's a good idea to join surfaces together even if you don't necessarily have all the pieces to make a fully closed solid from them.

If you can all the pieces in place to make a fully closed solid that will be best though because you won't have to worry about different possible orientations at all if you have made a solid.

- Michael

Michael,

>I see - but how was it that you noticed in Powermill that some surfaces were reversed in the first place, does it show some kind of indicator or coloring of the object side in there? If so then you could use it to do the direction tuning.<

They show up in a different colour. You can flip then in Powermill, easily done, but It should be done beforehand. Just for the sake of customer satisfaction :)

Customer are fickle, they like that sort of attention to detail...

Hi bigseb, sorry I'm still not quite getting it...

If you can both see and flip them in Powermill, can't you then do the flipping in Powermill and save the finished and flipped result back out from Powermill and then send that version with the surfaces oriented as you prefer to your customers?

Why is that method not working to solve your problem right now?

- Michael

It does work, Michael, its also an extra step. I could shave quite a bit of time by doing it all in one software. And time is money, after all.

Hi bigseb,

> It does work, Michael, its also an extra step. I could
> shave quite a bit of time by doing it all in one software.
> And time is money, after all.

At the moment if the flipped result is important to you, you'll need to do that extra step and that will allow you to get the result that you need right now.

In the future I do expect to add in a "show direction" mechanism that will show backfaces in a different color and let you solve this directly in MoI, but it is not in there currently.

- Michael