image to gcode

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13 Nov 2010 12:58 #5287 by eslavko
image to gcode was created by eslavko
Hello...

I just 'discover' that AXIS has built in image-to-gcode. And it's works.
But the output is so slow (full rastering) and simple image are slow to do.
So is there some chances to skip some unnecesary moves? Ie the whole line with Z over 0 can be skiped and similar?

so to carve simple image below should take few minutes instead near two hour?
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14 Nov 2010 14:56 #5299 by andypugh
Replied by andypugh on topic Re:image to gcode
That image would probably be a lot better converted to a vector format and then run through something like a DXF to G-Code converter.
I think that Inkscape should be able to vectorise the artwork.

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14 Nov 2010 18:55 #5302 by danand
Replied by danand on topic Re:image to gcode
Hiya,

I'm trying to do something similar BUT - I can't find where to set the scaling. My gif file
is a 150 DPI file but I find no whereto set/define - any ideas? Or did you just run your picture and hoped for the best?


Cheers

Dan

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15 Nov 2010 00:51 #5305 by KenC
Replied by KenC on topic Re:image to gcode
you can only scale the traced vector but not raster.

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15 Nov 2010 08:50 #5308 by eslavko
Replied by eslavko on topic Re:image to gcode
Hello.

The raster to vector (inkscape) works but result is not what I want.

The problem is that in this way for each line I got two vectors (left and right side) but I want thick line to be thicker (deeper with V cutter) and not just two outline's.
The image-to-gcode works better in this in mind (not perfect but...)
Is there any way to overcome that? (I use inkscape 1/2 hours total)

Thanks.

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15 Nov 2010 08:51 #5309 by eslavko
Replied by eslavko on topic Re:image to gcode
KenC wrote:

you can only scale the traced vector but not raster.


funny that. I just click on the corner handle and drag. The bitmap is scaled....

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15 Nov 2010 09:05 #5310 by KenC
Replied by KenC on topic Re:image to gcode
If you meant that, then the pix grain also "scaled" up to a coarser grain at the same time.

When I want the lines to be thicker, I just offset the vector loops in another cad program. so that the cam software can care them deeper wider with angled or bull nose bits..

Cleaning up the traced file is the ultimate PITA, but once done, the carving time will cut down to less the 10 minuse with this pix on a 600 x 600 (or approximately 2x2ft)

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15 Nov 2010 10:29 #5311 by andypugh
Replied by andypugh on topic Re:image to gcode
eslavko wrote:

The problem is that in this way for each line I got two vectors (left and right side) but I want thick line to be thicker (deeper with V cutter) and not just two outline's.


This was discussed in the context of carving text on IRC. Not that any conclusion was reached.
You would need a preprocessor that moved a variable-diameter circle so that it is always tangent to two lines.
There are commercial packaged that I think do this. There is one I see advertised around the place (seems to be Window only, but I guess might run under Wine) that allows you to download a demo: www.vectric.com/WebSite/Vectric/vcp/vcp_index.htm
I know nothing about it other than that it exists.

The image-to-gcode works better in this in mind (not perfect but...)
Is there any way to overcome that? (I use inkscape 1/2 hours total).


You might get results closer to what you want by blurring the original bitmap image to increase the range of get values and the width.

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15 Nov 2010 13:40 #5323 by eslavko
Replied by eslavko on topic Re:image to gcode
The Vectric is out of $$$ for my projects. It's to rare.

Maybe the solution is to make program to do the job.
I can spent few hour's to write it. But not exactly shure how to do the job.
On lines and V bit the problem is easy - just dig enought to get needed width. But what if line is wider than router?!?

....

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15 Nov 2010 14:25 #5324 by andypugh
Replied by andypugh on topic Re:image to gcode
I guess that the algorithm is simple in concept but tricky in practice.

The path is the centre of a circle that is tangent to the line being followed. The Z-height is chosen such that the circle touches another line (and all touched portions of that other line are deleted from the list) or the max depth for the cutter/material is reached. Alternatively, I suppose that you could default to minimum depth for such lines.

Choosing which side of any given line is the "inside" and which is the "outside" will be a fun puzzle.

The "list" I mentioned earlier might want to be prepared by breaking the curve down into short straight lines, then there are (I think) fairly efficient algorithms for finding lines that touch circles.

You might, for example, take the start point of a segment and walk the list looking for the line segment which has the shortest perpendicular distance to that point. The midpoint of that perpendicular line is a point on the cutter path, and the length of the line is the cutting circle diameter (which sets the z height). You then solve again for the other end of the segment, and add the path between those two points to the cutter path along with the two Z heights.

I think you might also split the "found" lines at the perpendicular points and delete the intermediate segments. But that needs a fair bit of thinking about.

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