The Make2D option seems to be leaving out some lines.
Very simple example:
As shown in the example, a line that is present in the model is incomplete. This one line is of course easy to fix and does not cost a lot of time, but some other more complex models are missing a lot more lines.
Cheers
Peter
Make2D has done this since Rhino1.
What I do is alwasy make 2D WITH hidden lines and then check if any of the lines that are should be visible are on the make2D hidden layer. And sometimes it just doesn’t manage to calculate the silhouette. But id say that 90% of the missing lines are on the make2D hidden layer.
Well the problem with that would be that the objects are so complex internally that it would be a lot of work to find out what lines you need. At least the way you explained it sounds as if I would get all the lines from the object in 2d.
Nah, the hidden lines are on a different layer, so you just turn it off, locate where the missing info is, turn it on and selects the curves and moves them to the correct layer and deletes the rest. Quick and easy.
Just try it.
I’ll give it a shot later today, I’m working on some renders at the moment. The make 2D takes around 1.5 hours without hidden lines at least.
Hi Peter,
To speed up the Make2D time you can
To set tolerance:
HTH
-Willem
Thanks for the tip Willem, Holo,
I’ll be continuing on this later today i’ll post my findings!
I’ve tried using hidden geometry too, but this just costs too much rendertime.
But in the first place, it would seem this is a bug rather we are working around rather then something that is intended.
Hi Peter.
The hidden linebug is absolutely a bug. So is the faulty contour that happens every now and then.
But the tolerance is not a flaw. Calculating at higher precision just takes more time.
I would agree if you think it is a flaw in the command that it doesn’t have tolerance built in, but it is not a bug.
Regarding hidden lines calculation, it should not take any longer at all, as Rhino has to calculate all the lines and filer out what is visible anyway. I have not tested this, as logically it should not make a difference. Have you tested that?
Yes that is what I meant, the missing lines is the bug part 
The tolerance vs time is logical. I’ll be doing some more 2d conversions soon so i’ll notice soon enough in what proportion the tolerance will lower make2d time
This actually worked for me, I set absolute tolerance to 0.00001 and all of my lines got drawn. What a relief since I was getting ready to redraw all the lines. Thank you.
Hero!! 
It’s an absolute joke that the issue exists since Rhino 1 and here I am in Rhino 7 missing 10% of lines
The algorithm can only be improved when specific files are provided. That’s a necessary condition but not necessarily sufficient.
-wim
It is missing lines everywhere basically, i a not very happy about this… fairly simple geometry, just pipe on arcblend curves
Hi -
i know but this issue seems to date a decade back. i doubt that you havent got many failing examples already. i can send you this one but via email.
here you have the file with railing. make 2d is a total mess.
have a look pleasemake2dissues.3dm (1.2 MB)
i am approaching deadlines on a project and i cannot rely on make2d. i am bit stressed out…
I see lots of issues with Make2D too.
Here is a simple example on a mesh:
See how it treats the quad differently from the triangulated mesh, leaving lots of gaps and holes.
The scene silhouette is also a messy thing with holes in it.
The mesh is made from quadremeshing an extrusion and then adding “noice” to the vertice locations.
MESH make2D.3dm (375.5 KB)
Here you can see that the make2D visible lines doesn correspond well with the polygons that actually are visible: (Some creases are hidden, but make2D still chooses to show them)
How Terrible is it that after 8 years this is still a problem… and according to a post from around that time this problem already stems from Rhino 1…
(I’ve switched jobs a long time ago so I don’t have acces to the files, but it was not really an exception. It happened with almost every file)
