[c#] imageprocessing

Hi all! I am trying to do hough circle transform in c#. in face I want to input an image to grasshopper and took curves as a ressult. I know there is Aforge.Imaging namespace to image processing for c#.net, but i dont know if that is possible to use it in grasshopper too? may be a source code of hough transform in c# helps to. please consider I am new in c#! thnx!

Replies to This Discussion

Permalink Reply by peter fotiadis on September 6, 2016 at 12:09pm

I have no idea what AForge does but :

You want to sample ponts from some list based on another (RGB values) and then do something?

For instance use a concave hull algo on all except the black points (and thus get the "outline").

Or use some ball pivot algo (not Delauney) and get some "sketch" as mesh

Or select all that have RGB values within a given domain and then ... er ... hmm ... what?

Permalink Reply by David Rutten on September 6, 2016 at 12:24pm

Aforge is a non-standard assembly, so unless you have a copy of it you cannot use it. If you do have a copy of it then that assembly can either be referenced directly by the C# component or you can PInvoke it from code. However if you plan to distribute your script, then you must also be sure that you are allowed to distribute the AForge.dll

I'm not entirely sure how you're going to output curves from applying a hough transform to a bitmap though, you'll need to elaborate on that.

Permalink Reply by peter fotiadis on September 6, 2016 at 12:42pm

Anyway basic RGB "filtering" stuff "like" this is rather simple (and getting "outlines"/meshes as well, so if this is actually the requirement - and not curves - is entirely doable within GH)

Permalink Reply by peter fotiadis on September 7, 2016 at 1:38am

Used classified BPA and Concave hull C# : they indeed do some stuff but well ... image processing is a huge hot cake (and properly prepares the nightmare of tomorrow: Brave New World etc etc).

mesh with BPA:

Various Concave Hull solutions (depending on sensitivity):

For doing things using solely GH you'll probably need:

island detection,

polyline smoothing,

some sort of hard flat clustering,

fast BPA/Concave algos,

See attached: using a non even random point very simple C# that for huge amount of points is obviously faster than David's stuff (but this of course makes even distribution and thus is maybe better for the scope). C# does the "normalized" points job as well.

If you opt for using David's component on some rectangle you'll need to remap the x/y coordinates (0-1) for the Image sampler.

Attachments:

Colors_to_something_V2_public.gh, 224 KB

Permalink Reply by peter fotiadis on September 7, 2016 at 3:20am

And this makes(?) some(??) sense(???) more(????).

Attachments:

Colors_to_something_V2A_public.gh, 228 KB

Permalink Reply by ghazal on September 6, 2016 at 12:41pm

Hi David, ofcourse I am not going to crack Aforge, but I was thinking if I can import it to grasshopper c#. So I found that is not going to happen.
I think I can use another ways too. Like what peter mentioned... thank you ☺

Permalink Reply by ghazal on September 6, 2016 at 12:42pm

Peter I think I can use something like that to do what I want. I will try and send it here, thank you ☺

Permalink Reply by peter fotiadis on September 6, 2016 at 12:49pm

Well .. if you want huge amount of random points it's advisable to write a small C# that do these without the "even" distribution that David uses (thus taking some time more).

For fun I'll try some (internal) concave algos to see what happens - but if memory serves there's one around that is not classified (using a convex hull as a base guideline).

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