Utter Noob Q: Convert hand drawn curve to efficient one

Hi Guys!

I normally work in 3DS Max (please don’t throw produce at me) but I’ve been asked to figure out a way to convert hand draw curves in Rhino into a more efficient curve with the least number of points. I’ve done my best to figure it out but the learning curve is a bit steep lol

In the image below you can see what I drew out in Rhino and the number of points it produced on the left. On the right is what I produced in Max as an example of what I’m hoping can be done in an automated fashion, or in as few steps as possible. I tried the Rebuild tool but it requires a lot of points to get close to the intended shape, but there is still enough deviation that it’s not viable, at least what I was able to produce. It’s entirely possible that such a tool doesn’t exist or it will be more steps than desired, but my boss asked me to look into just to be sure. Any help would be greatly appreciated!

Hello - if the optimized curves are arcs or series of arcs, (your image looks like it might be…) then there are probably enough options in the Arc command (like Arc > Start >End >Point on arc) and the ArcBlend command to help. If not, then it’s harder… are the curves 2d? Can you post a few examples?


Hi Pascal, thanks for the reply!

I believe they are. If by arc you mean the line segment between two points then yes they are. The attached image shows the control handles/points that give it the shape it has. Apart from the end points, the points near the bottom represent the tangents it would need to create and the point connecting the two larger arcs was placed because there would have been too much deviation in that area so it was added to accomplish the right amount of fidelity.

As for additional examples, do you want to see more “optimized” examples? They are in 3d btw. In Rhino I’m drawing on the surface of some CAD data.

I tried to use the Arc command but it was creating a new curve and Arc Blend connected the end points together. I’m looking for something similar to Rebuild, but that gives me a result that is more in line with the “optimized” version. It could also be that I’m not sure how to do what you are suggesting lol

Hello - I was hoping you’d post a 3dm file with one or more typical curves that you need to noodle with- that way I can have a try and maybe come up with a reasonable workflow.


Oh sorry about that! Here is the file I’ve been testing with. It doesn’t contain the data I was drawing on because I can’t share that, hopefully that won’t be an issue.

Here are a few - does that do any good?

TT_curves_etc.3dm (356.8 KB)
@bacree - V5 format now.


Is it possible to save that as Rhino 5? I don’t have version 6 :confused:

Thanks for putting this together! The blend between two Arcs looks like it might have a few more points than needed but the others look good and seem to represent the shapes as efficiently as I would need. Are these still in the vein of having to define start/stop for each arc or set of arcs I want to optimize?

I guess another question would be, is there a more direct path to get those without having to “trace” lines on a surface using the Polyline tool?

…on second thought, this is moot because the essence of what I need to determine is still how to get from an inefficient/low resolution line to a smooth curve.