How to trace a line drawing image to be a “”real line“ vector drawing instead of a outline image?

iarch · April 11, 2020, 4:51pm

I found that rhino command “trace” is very powerful to trace a image to be a vector file, like this

but what I need is a “real line” vector drawing, that means the new drawing is shape by vector lines with same width not by outlines of former lines.
Do I make it clear? Another GH plugin I try the “Rooster” is same as the Rhino “trace” command.
rooster.gh (9.5 KB)
I thought maybe the image sampler is the right method but I don’t know how to write the scripts. Is there anyone who know how to do it? Thank you so much!

laurent_delrieu · April 11, 2020, 5:07pm

Hello
I am not sure I understand. You have an image and you want a vector plot of it. So yes Rooster is a good option. Rooster is based on Potrace
http://potrace.sourceforge.net
If you want to use Rooster use Crvs it is the geometry.

JimCarruthers · April 11, 2020, 5:28pm

He wants a vector drawing that rationalizes the ‘thick’ lines in the drawing to single vectors. That sound fairly impossible.

If you could get a version that’s ‘filled?’ Use Photoshop to fill-in the lines? Or reduce the resolution until the lines merge?? What is the point of this exercise?

iarch · April 11, 2020, 5:44pm

I think maybe it is possible because the Illustrator got this function but it is too rough and the most important thing is AI don’t get so many variable to adjust compare with GH. like this one.

so I guess maybe GH got this function too by using image sampler.
sorry for my poor English.

laurent_delrieu · April 11, 2020, 5:46pm

Image sample has not this function.
Can you post a link to the image? It more easy to help with a support!

iarch · April 11, 2020, 5:48pm

Thank you Laurent, you always provide so many useful resource, I like this kind of pages which are sharing the great amount of their researches!

iarch · April 11, 2020, 5:55pm

Yes, I forget to upload that original image?sorry

I draw it by hand copying from a old book of traditional ancient drawings as below to make the lines more clear at first step.

And next step is what I ask above.

iarch · April 11, 2020, 6:08pm

This pic from AI. And the line width is variable.This is what I mean “real line” vector image.

laurent_delrieu · April 11, 2020, 6:23pm

The only tool that I know to do what you want is Medial Axis. There was many discussion on this forum on this technique. I doubt it will work here. The tool you need is Rooster/Potrace with an option that I don’t know if it exists. You need something with curve with variable thickness.
We had a discussion of Potrace, so you could surely have more options.

It seems that there are some other tools

I tested a bit Vextractor that has some ability to extract median curve.
traditional graphic.3dm (614.3 KB)

iarch · April 12, 2020, 6:47am

I try all the 5 tools and I believe that AI still be the best one which could do the both “single line” and “outline” vectorize things. However Wintopo is a quick one and free. Please see the comparison of this two.

Thank you!

laurent_delrieu · April 12, 2020, 7:21am

Thanks for reporting. It is always useful for future questions like that.
I suppose that like many “reverse engineering” question form this forum, the best tool to do this type of job is not an automated one but someone skilled with a drawing tool.

JMR · March 31, 2021, 1:36am

What a great topic!

I would like to do exactly the same thing:
Convert JPG/BMP/vector (whichever, I can prep in the Photoshop beforehand) → and get just the curves or even just the curve outlines in Rhino. For some reason the rooster plugin doesn’t seem to work for me?

wim · April 3, 2021, 7:49pm

Hi -

You can try the Vectorize plug-in - it is available through the PackageManager.
-wim

ohmarinus · June 14, 2021, 10:40pm

Right click ‘image bitmap’ on the component and select a single bitmap file. This is how it works.

However, I’ve been playing around a lot with rooster and I do not think it actually works that well. Threshold seems to be broken for example, and it throws out a lot of almost similar curves. These curves are similar enough to be annoyingly overlapping, but they are too different to be effectively filtered out.

I wish it worked a little better. The RGB values that are split together with the curves have a great potential to be used, but the before mentioned issues make it very hard to use well really.

There is a lot of choice and sadly none of the plugins I’ve found so far seem to do the job I’m looking for.