Extract Curves from Raster Image

[scottyvalentine (Scott)]

Hi all,

I’m finally getting into teaching myself Grasshopper and one significant task I want to figure out is how to extract a curve from a Raster file. I see there are tools like Vectorize and I believe Rooster used to be available but now isn’t. These tools produce an outline of the pixels produced by line width.

Are there any GH Nodes that are able to approximate the centre of a raster line and draw a curve like the in-built sketch tool in Rhino? My goal is to be able to take hand-drawn contours and turn them into curves.

[tay.othman (tay.0)]

Vectorizing a raster image is a complex coding exercise. Some people in this forum created sort of tools to achieve this.

There is definitely no image trace component comes with GH right of the box. But you can make one if you are interested in getting into coding.

[scottyvalentine (Scott)]

@tay.alrawi

is definitely no image trace component comes with GH right of the box. But you can make one if

Thank you Tay,

If there’s nothing already existing I’ll put this on the to-do list once I’m comfortable with the existing tools I need to solve my problems. I could see it theoretically being possible, eg take the two traced edges and tween between them, however, I’m only halfway through the Rhino.Inside guide so I’ll finish that first.

Thank you for responding.

[scottyvalentine (Scott)]

I found some earlier discussions on this topic. Looks like I didn’t search hard enough earlier.

Turn Hand Sketch Lines/curves to Rhino vector lines/Curves

Thanks for your quick reply, clement. I have tried the Vectorize plug-in, it is quite nice, but seems it is doing the similar thing as Rooster did… It is also tracing the color boundary. I am curious if it can be set to trace the hand sketch as single lines, rather than double lines. Or maybe it is right to trace the color boundary for the first step, but need another magic to turn the boundary to be single lines/curves? [Step1 Vectorize] [Step 2]

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

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 gra…

Help needed with finding centre line through 2 curves

again, un even results with meancurve method [09]

[old_taz]

Some good raster image to vector outlines ideas here:

Create a “Paint by Numbers” script - Grasshopper - McNeel Forum