Hi Danny,

> I think Rado is saying that the silhouette command doesn't
> work quiet well on this model and hidden lines are being
> generated

Yes, that's what I was trying to describe - silhouette currently will generate all "potential" silhouettes, which for curved surfaces means tracing a curve where the surface normal is perpendicular to the view, and for a joined creased edge (when "Include edges" is enabled) it means an edge that has a surface normal on one side pointing towards the eyepoint and the other surface normal on the other side of the edge points away from the eyepoint.

Later on I want to have some additional methods that will take these potential silhouettes and figure out which pieces of them are hidden and which pieces are visible.

Right now that hidden-line processing is not done, so you get all potential silhouettes generated, including ones that would be hidden.

I can't see anything actually going wrong with the silhouette generation in the model you posted (given the way Silhouette currently works with "potential silhouette" generation as described above), can you maybe point out one particular silhouette line that you think is an error?

- Michael

I see Michael, when you describe how silhouette is working and is missing hidden line 'removal' then it all makes sense.

Cheers

Yeah...

It works better for some cuts than others. This weird off-axis cut for example doesn't give the result you would expect. Reading Michael's description of how the command works, I see now why that's the case.

"Later on I want to have some additional methods that will take these potential silhouettes and figure out which pieces of them are hidden and which pieces are visible."

This would be amazing. Does Rhino currently have something like this? I have access to it at school...

The attached image shows the cut on the right that was performed with the silhouette command (the one on the left is the one I traced and how it should look from this perspective view).

Hi Rado,

> This would be amazing. Does Rhino currently have something like this?

Yes, Rhino has a command called Make2D which will generate a hidden-line drawing of your model. It puts the output as 2D curves that are flat in the Top view.

Rhino also has a silhouette command, but it seems to duplicate every creased edge of a solid no matter if it is a potential silhouette or not.

I may be able to tune up MoI's silhouette generator for edges on solids a bit more by also trying to figure out if an edge is a convex edge of the solid or not, and only allowing it as a potential silhouette if it is.

- Michael

Cool. I'll have to try it at school tomorrow. Thanks for the help!

Other problem with the silhouette command is that you cant make it work with multiple objects, i mean MoI doesnt know if an object is behind other object, it just makes one silhouette for each one.

Hi Ed, yeah right now Silhouette can just give you the sort of "raw materials" of various potential curves to use, particularly on curved surfaces where there may not already be an edge in the model along the silhouette line. But then you need to manually process them to delete and trim out pieces that you want to remove.

- Michael