2d-tracing of an image

I was trying to figure out how to trace an image directly by grasshopper.

It is really time consuming if I manually trace a complicated image using the bitmap method.

If possible can anyone post the grasshopper file for tracing image.It doesn't need to be very accurate.

There had been a discussion on it before but it did not give me the output as I saw.There might be some error in the file I created.

Could anyone post the working grasshopper file for it?

Thanks in advance..

Attachments:

edge_detects.gh, 225 KB

Replies to This Discussion

Permalink Reply by Olivier TURLIER on February 8, 2016 at 1:53pm

Hi Shubham,

Your image looks as a perfect candidate for potrace ...(raster to vector soft)

Sorry, I'm of no help at all for grasshopper ...

Cheers

Permalink Reply by Laurent DELRIEU on February 8, 2016 at 3:17pm

I think you could use Daniel González Abalde tool :

http://www.grasshopper3d.com/photo/rasterize-images-in-black-and-wh...

with a res of 0.5:

Permalink Reply by Shubham on February 9, 2016 at 12:51am

Coluld you please attach the grasshopper file you used for it.
Thankyou for your prompt reply.

Permalink Reply by Laurent DELRIEU on February 9, 2016 at 1:47am

It will be useless now
First You have to upload Peacock plugin, on food4rhino I think
Put vectorize component on your canvas
The path of your image on a panel and change res and str if needed
That s all!

Permalink Reply by Laurent DELRIEU on February 20, 2016 at 2:28pm

potrace seems good, whitout changing the image just copying in bmp and using potrace

with these line command

potrace 1.bmp -o u1.svg -s -u 1
potrace 1.bmp -o u10.svg -s -u 10

potrace 1.bmp -o u10.dxf -b dxf -u 10

DXF in rhino

Attachments:

u1.svg, 61 KB
u10.dxf, 847 KB
u10.svg, 79 KB

Permalink Reply by Nik Willmore on February 20, 2016 at 2:40pm

What's potrace? Good results indeed.

I see: http://potrace.sourceforge.net/

They are using a sort of look-a-head strategy with smarts, not smoothing:

http://potrace.sourceforge.net/potrace.pdf

Permalink Reply by Shubham on February 23, 2016 at 8:54am

Thank you for the reply.

I wanted to ask how to get potrace working for rhino.

I downloaded the 64-bit zip file from sourcefourge and extracted it in rhino plugins but it says unknown command .

Please help.

Thank you in advance.

Permalink Reply by Laurent DELRIEU on February 23, 2016 at 2:01pm

Potrace is not a plugin for Rhino it is an executable with command lines. So here are the steps I used :

Unzip potrace zip
Put it somewhere on your disk, me I named a folder "c:\potrace" it is more easy to call program when they have a short folder name
put your image in format BMP on this folder
make a file with an extension ".bat".
Open this file with atext editor (notepad++ for me, but notepad is enough).
Copy in this file the line "potrace yourfile.bmp -o yourfile.dxf -b dxf -u 10 " whithout quotes
Save the file
Double click on file.bat so it is executed (it execute the line command)
Open "yourfile.dxf" with Rhino

Nik method is more simple you have to specify files (potrace.exe and yourfile.bmp) but you need GHPython (http://www.food4rhino.com/project/ghpython)

Hope it helps

Permalink Reply by Shubham on February 23, 2016 at 10:34pm

Thanks a lot.
It worked perfectly.

Wanted to ask if I could use GHPython as a plugin for inbuilt rhino iron python.

Would it be easier or its better to use normal python environment?

Again a thank you for all the help.

Permalink Reply by Nik Willmore on February 24, 2016 at 8:23am

I prefer working on the Grasshopper canvas since I can prototype solutions and post-process output before having to hard code it with Rhinocommon help file frustrations, and I enjoy the Grasshopper preview that I can often turn meshing off for when things are going slow debugging and tweaking.

No, I wouldn't somehow link native Rhino Python editing system to Grasshopper Python, both which access IronPython, but would have to "port" the Grasshopper version to Rhino itself, and then you lose the free Grasshopper preview so would have to add code to push the created geometry stored in Python lists into Rhino, like a baking step in Grasshopper. Fairly straightforward boilerplate technique.

I'm barely familiar with the native Rhino Python system though and am not sure how to store or initiate Python as commands, nor how to share a script and associated command name assignments with others. I mean how do scripts install and *stay* installed unless you re-save your various unit template Rhino files, since a script isn't a plug-in? Is there a separate scripts directory and scripts menu or something?

Educate me if you want help on this.

Permalink Reply by Nik Willmore on February 20, 2016 at 1:43pm

There's a way to have grand control over the result using Photoshop. Change to grayscale, then up the resolution way up and Gaussian blur to very effectively smooth any pixelation. Then use the Wand (not contiguous) to select the black and make a work path from selection in the Paths palette and the secret is to use the Alt key to bring up the Tolerance setting in order to set it small.

Original after using the Levels command white eyedropper and clicking on gray to make the watermark crap white too:

Upping the resolution by 3X:

Gaussian blurring a whopping six pixels:

Using Curves to tweak the result, beefing up details, then use Threshold to see result. Now create a Work Path from the selection, crucially using the Alt key to also bring up the Tolerance setting for the work path, using 0.5 pixels to make it not be crude:

Now you can export the path to Illustrator that Rhino can open:

The point of all this is that it gives you full control over the result. In haste I've lost some detail, but I'm also able to create smooth tracings even from pixelated artwork. You can see I'm already pulling a lot more detail than Laurent's example:

Even though the image is pixelated, the nature of these type of bezier curve artwork means the information of the original is still there as long as you average the pixel outline using blur.

Permalink Reply by Nik Willmore on February 20, 2016 at 2:01pm

Being a bit more careful with my initial Curves tweaking, along with Threshold use, here are the overly complex 0.5 pixel Tolerance Photoshop selection work paths, and a much simpler one with 1.0 Tolerance setting, turned into shaded surfaces using PlanarSrf in Rhino: