Bitmap to Vectors?

Bill Arnold

1974
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Thomasville, GA
Several software options I've been working with provide bitmap tracing to create vectors needed for CNC toolpaths. However, the results so far are, at best, not quite where I want to be. I've even tried a couple of online graphic conversion sites and still no love! The issue is that the conversion process doesn't produce a clean, single line vector; it has width that gets interpreted as two lines when creating toolpaths. When trying to cut a fairly detailed graphic, the extra lines destroy facial features, etc. Does anyone have a suggestion or three?

I was having a similar issue with fonts but Dan Noren clued me into the solution: single line fonts. Yep, it was that simple!!!

Thanks in advance for your help!!!
 
Ryan, I used Inkscape quite a bit when I first set up my CNC machine. It's good for a lot of things, but yields double or broken lines on a bitmap trace - much like I see in other software.

I've traced drawings in SketchUp but they were nowhere near the detail in some of the graphics I'm trying to use now.

The bottom line might be that I have to re-think some of what I'm trying to accomplish.
 
Vectric Cut 2D desktop or any Vectric software about that would make that problem "go-away"

You get total control on vectors.

I've been evaluating Cut 2D and VCarve Desktop and get similar results. They do marginally better than freebie products but they still read and plot both sides of the bitmap lines.
 
Ryan, I used Inkscape quite a bit when I first set up my CNC machine. It's good for a lot of things, but yields double or broken lines on a bitmap trace - much like I see in other software.

Hmm, I see what you mean looking closely at the generated paths. This seems like it should be solveable... somehow... maybe..
 
Hmm, I see what you mean looking closely at the generated paths. This seems like it should be solveable... somehow... maybe..

The first time I used Inkscape to trace a bitmap, I thought it looked good and saved it as an SVG. Then, I loaded the SVG into MakerCAM, created toolpaths and thought I had screwed up something. Repeated and got the same. Then, I drilled in real close and found that what looked like solid lines were combinations of double lines and broken lines. I gave up on that combo after hearing about F-Engrave and trying it.

F-Engrave handles a bitmap trace well enough I can use it - up to a point. If it's something I want for an etching, it's fine - mostly. It's a very situational thing.

One of the images I've been working with is attached below. When trying a bitmap trace, the eyes and the stripes across the front of his shirt start running together because of the double trace.

Campfire800.jpg
 
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Tried the picture you posted in Corel. When converted to vector it has mostly the double lines.

Thanks for checking it, Pete.

It might be asking too much of any software to process a drawing like that with so many lines so close together. It's impossible to do a v-carve cut with the double lines; an etch looks better. The worst part is the eyes since there are so many lines around them.
 
Cut 2D --- V-Carve Pro --- Aspire are all exactly the same in that respect. One is not better than the other.

Yes when you do a bitmap trace there will be a double line.

Lots of people, pro and hobby alike will not do the bit map trace, but rather manually trace the image and adjust the vectors. That gives the best quality trace.

To date - I have not heard of any bitmap trace that does it any other way.
 
That's exactly what I did with the car cribbage boards, loaded the drawing to sketchup, then redrew them line by line.


That's what I've done with drawings similar to your cars. SketchUp makes it pretty easy to do, but the drawings I'm trying to use have a ton of tiny lines and I don't have that much patience.

One thing I tried a few minutes ago was to take the original of the drawing I posted and enlarged it by a factor of about five. That presented a lot more detail to VCarve and it made a smoother trace, still with double lines but somewhat smoother and closer together. I'll do an etch with a 30° bit tomorrow and see what happens.
 
Vectric Cut 2D desktop or any Vectric software about that would make that problem "go-away"

You get total control on vectors.

Cut 2D --- V-Carve Pro --- Aspire are all exactly the same in that respect. One is not better than the other.

Yes when you do a bitmap trace there will be a double line.

Lots of people, pro and hobby alike will not do the bit map trace, but rather manually trace the image and adjust the vectors. That gives the best quality trace.

To date - I have not heard of any bitmap trace that does it any other way.

OK...
 
indian.jpg

Bill,

Is this what you are trying to do?

I did not do any vector editing at all. The area around the eyes could use some editing, as you said, but that would be pretty easy.


After I did the trace, I created a toolpath and then previewed the toolpath.
 
Leo, I worked with the eyes a little this morning and can improve them with some editing - still learning.

On the "Trace Bitmap" page, do you change any of the settings from the default? I used Black/White as the type and have tried adjusting the other three parameters different ways - still playing with that.
 
What I did was use the black and greys and not the white. I use red as a preview color so I can see what is being selected as I click on the grey shades. I selected all the black and grey shades.

I did get the double lines. That is just how the bitmap tracing works.

For the toolpath - I used the V-carve/Engraving toolpath and selected all vectors. That is available in V-Carve Desktop and up - but not available in Cut 2D - sorry.

If you are editing the vectors around the eyes, you need to be cognizant as to how the V-Carve toolpath works. This toolpath uses a "V" tool and the "V" fits inside the double lines. The tool will cut as deep as it can fit inside the vectors. The vectors MUST be closed - like a box or rectangle - not two parallel lines. If the vectors are not closed you will get very weird results.

Sooo - your edits around the eyes need to be closed double vectors. If you like I can do a little demo for you.
 
If you are editing the vectors around the eyes, you need to be cognizant as to how the V-Carve toolpath works. This toolpath uses a "V" tool and the "V" fits inside the double lines. The tool will cut as deep as it can fit inside the vectors. The vectors MUST be closed - like a box or rectangle - not two parallel lines. If the vectors are not closed you will get very weird results.

Sooo - your edits around the eyes need to be closed double vectors. If you like I can do a little demo for you.

Ok, I'm slightly confused at this point (and my lack of practical CNC experience is shining brightly through here :D). I've been playing with cleaning up some vector traces of bitmaps (and Bill, I'm certainly understanding your pain!!) and thought that the goal was to only have a single path line for the trace. This indicates that assumption is not true but if I have boxed vectors it will cut within them and thats ok?

If you could do a zoomed in snapshot of what the vectors should look like for a proper cut path that would be exceedingly helpful for me to grok this.

Also thanks for all of your (all of you but especially Leo) explanations thus far on the whole CNC world, its been very interesting and educational.

Not that I'm planning to get a CNC... no room.. really.. but if it were to happen.. you know :rolleyes:
 
In VCarve Desktop, the choices in Trace Bitmap are Color and Black/White. I've played with the Color setting, reducing the colors to a range of black to gray and it works OK. I get more what I think I need using B/W, choosing just black then editing around the eyes.

I had to add an engraving tool to the list: a 1/8" with a 30° pointed tip. The final engraving preview looks quite different depending on the specific type of bit, as you know.

Another factor I thought about is whether I engrave this plaque on maple or walnut. I originally planned to use walnut with light filler but now I think it will present better with dark filler on maple.

This is another example of my tendency to analyze the daylights out of something! One of these days I'll plan stuff and just build it!!! (...yeah.....right...)
 
... If you could do a zoomed in snapshot of what the vectors should look like for a proper cut path that would be exceedingly helpful for me to grok this. ...

Coincident with your request, I've been looking at that very thing. Below is a series of screenshots of VCarve Desktop closeups of the graphic I've been working with.

Frame 1: The graphic after running bitmap trace.
Frame 2: Toolpath trace using an engraving bit.
Frame 3: Engraving preview using a default bit in VCarve - 40° with .002" flat one the end. DoC is 0.015"
Frame 4: Engraving preview using a 30° pointed bit. DoC is 0.015"
Frame 5: Preview of the cut using a 60° V-bit at a maximum depth of 0.043"

Screenshot 2015-07-11 14.03.43.jpgScreenshot 2015-07-11 14.07.50.jpgScreenshot 2015-07-11 14.12.15.jpgScreenshot 2015-07-11 14.12.54.jpgScreenshot 2015-07-11 14.31.37.jpg

The engraving bits follow all of the lines generated by the bitmap trace; i.e., both lines of the double line result of the trace. The better looking cut is the last one that uses a V-bit, which cuts between the lines of the double line trace.
 
Another update:

Below are closeups of the face of the subject in the graphic I'm trying to use.

Frame 1: Preview of the cut using a 60° V-bit at a maximum depth of 0.043"
Frame 2: Engraving preview using a 30° pointed bit. DoC is 0.015"

Screenshot 2015-07-11 14.47.24.jpgScreenshot 2015-07-11 14.48.40.jpg

The eyes render much better using the V-bit, which surprised me somewhat. I had edited the vectors around the eyes before these cut tests.
 
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