Having trouble aligning multiple images to form one large image

[BryanBrady]

I am trying to take a large image that I have separated into multiple smaller images and put it back together.  I am trying to laser engrave the image and the file is too large for the system to process so the instructions told me to break it up and then put it back together as separate images so that the software can process them independently.  The company recommended Inkscape and I am having trouble getting the images to line up without spaces between all of them.  I have tried adjusting the spacing under the Arrange tab but I can't get it to do anything.  Under the Align and Distribute tab I have tried adjusting the overlaps and that doesn't appear to make a difference either.  If I could get push in the right direction I would appreciate it.  Most of the file types I am using are jpeg.  If I need to use a different format please let me know.  I have tried to attach an example of the problem.  I am new to this so I might have screw up.  I appreciate the help.

[TimiZero]

Hi Bryan, i know nothing about laser engraving, but if you're wondering about the small gap between the images, that's the known problem of inkscape (also have seen people reporting similar thing in AI but probably for a more complex path). I failed to find the related tutorial, but the known workaround would be to duplicate few times and leave the duplicates stay on top of the original;
select everything by mouse --> press 'CTRL + G' to group them --> press 'CTRL + D' once or twice to duplicate...

There's another way which is by creating a rectangle (without stroke) same Height and Width with the 'combined image'. Pick whichever color from the image for the rectangle fill (in your grayscale case i would probably choose the mid shade). Then, align and put it underneath everything (make it bottom-most object by pressing END on keyboard).

That's the solution for the 'gap on screen' though. I'm not sure how the engraver works, so you may want to wait for a more appropriate answer from experience users.

[brynn]

Welcome to the forum!

Let me understand better why the instructions want you to split the image?  It certainly is not too large for Inkscape.  And it looks like it's less than 200 mm in both dimensions.  What kind of machine is that too large for?

Also, how did you cut it in the first place?  Generally, I think you just want to cut it in half, and don't move the 2 parts.  That way, they stay aligned properly, and you don't have the nightmare of re-aligning them.  But if you cut it for example using scissors, and then you scanned in the 2 parts, that could be nearly impossible to align them.

But again, I'm wondering whether it really does need to be cut in pieces.

Depending on how you cut it, it might be possible to snap the 2 pieces together, which except for using the actual coordinates and piece dimensions, would be as precise as possible alignment.  Even though it might not look aligned (because of anti-aliasing) it would be aligned. 

Can you share the SVG file with the 2 parts imported?  Then we could give specific instructions.

Does your machine engrave from a raster image?  Or will you be using Inkscape to create the vector paths for cutting/engraving?  If so, it would probably work better to cut the image after it's converted to vector paths.  Because Trace Bitmap (if that's what you're planning to use) will actually draw that line where you cut it, and your engraver would engrave that line.  Definitely not what you want!

I'd be curious to see the tutorial or instructions you're using.  That's something this community lacks, is a large selection of tutorials for using Inkscape as part of  engraving or gcode cutting and etc.  I've tried to write some, but since I don't actually have any cutting machine, they aren't very good.  So if it's a good tutorial, I'd like to add it to our collections.

[BryanBrady]

TimiZero I appreciate the information and I will need to mess around with that and see if it fixes the problem.  Brynn the image that I posted is only a part of the entire picture.  The laser engraver I am using is called a Glowforge.  The software that it uses is online so I don't have a specific name for it.  The software actually creates all the needed information to burn the image from whatever format you send to it.  I have tried sending a .jpg and several other formats and the software didn't care about the format type it only cared about the size of the file.  The instructions that we were given were from the Glowforge website and they suggested splitting the image using https://postcron.com/image-splitter/en/  The next part was to use Inkscape to assemble them back together so that it looks like one image again.  Using the file saved from Inkscape import it back to the Glow Forge website and it would see that it was multiple images and would process them independently.  Because of the multiple smaller files it would burn them one square at a time but because of the spacing between the images in Inkscape the laser engraver also put the spacing in.

I don't know if Ink Scape has the ability to split the image without creating the spaces between the new pieces or not.  I will need to look into that more.  I am including a link to the Glowforge main website so you can see what I am trying to work with.  I appreciate both or your responses.

https://glowforge.com/?utm_source=google&utm_medium=cpc&utm_campaign=brand&utm_source=google&utm_medium=cpc&utm_campaign=Search-Brand_Prospecting-All-Hear-GP&utm_term=glowforge&utm_device=c&gclid=EAIaIQobChMIiq2fpKPP3wIVQRh9Ch19JgygEAAYASAAEgKg5PD_BwE

[Moini]

You shouldn't include anything after the / in the url...

[TimiZero]

because of the spacing between the images in Inkscape the laser engraver also put the spacing in

Hi, bryan. I've just checked the link you posted (the postcron), and it looks like the main purpose is to achieve collage-like photos. In that case the small gaps are probably intentional.

I've uploaded dummy file and put some of them back in inkscape. Here how it looks like

Screenshot_2019-01-03_19-25-11.png
(236.53 kB . 1052x730)
(viewed 186 times)
I also added 3 rectangles above the split image. As you can see there are also gaps between the rectangles but you need to look very closely to see it. On the other hand the gap between the images are too obvious, and it's definitely not the inkscape problem like i mentioned in my earlier post. If the gap lines appear when engraving, then you probably need to use different program to split the image.

[BryanBrady]

Moini sorry about that.  I will do better in the future.  Timizero I appreciate you also looking at this problem.  I originally thought that it was the program that was splitting the image as well until I tried several different programs and got the same results.  I even used photo shop and cropped the image into several pieces myself and then tried putting them together using Inkscape and had the same results.  I will try using the grouping and duplicating suggestion that you made in your previous comment and see how that works.  Thanks for the feedback.

[brynn]

I would use Inkscape to split the image.  It does not have a tool (yet) to do it on the canvas, but it can create them as separate images, which you can then import, and snap together.  Use Extensions menu > Export > Guillotine  Here are instructions:

1 -- Import the whole image into Inkscape
2 -- Create Guides and place them wherever you want the image to be cut.  The guides are literally the cut lines for this extension.
3 -- Run the extension, after creating or defining the folder where you want them exported.
4 -- Import all the resulting PNG images.  (File menu > Import)
5 -- Set the Snap control bar like in the attachment
6 -- Drag the pieces so that the matching corners are close to each other, and you will see the piece on the mouse sort of jump away from the mouse, and snap to the other corner.  Snap them all together.

You will still see a visible gap, but that can't be helped at this point.  The pieces are literally touching each other.  The visible gap is a result of anti-aliasing. 

I'm not actually clear if the gap is a problem, why your instructions want you to use that instragram tool to create a gap.

But in any case, there is one, or maybe 2 ways to fix the "gap".  One is to overlap the pieces very slightly.  The arrow keys move an object by 2 px, which ought to be the perfect amount to cover the gap.  So select a piece and press an arrow key once, and repeat for all the pieces.

The other way, which I'm not sure if it would work....oh hey, it does work!  Ok, File menu > Document Properties > Page tab.  At the bottom, uncheck Use Antialising.  Uncheck that before you use the extension to slice them up.  Then when you snap them back together, there won't be a gap!

[BryanBrady]

Brynn I will try that out later today.  Thanks for looking into this and giving me some options.

[TimiZero]

I originally thought that it was the program that was splitting the image as well until I tried several different programs and got the same results.

Sorry for the late reply, and I think you're right. I tried using extension suggested by Brynn and have noticed that the gap is still there.

I will try using the grouping and duplicating suggestion that you made in your previous comment and see how that works.

Not sure if you would need it, since that just fix the aliasing problem on screen. I'm sure the engraving machine will read it differently.

I would use Inkscape to split the image.  It does not have a tool (yet) to do it on the canvas, but it can create them as separate images, which you can then import, and snap together.  Use Extensions menu > Export > Guillotine 

Thanks Brynn for introducing this extension. If not, I would never know what it's for (and it's existence...LOL ). On my computer it doesn't work as intended though. Maybe I still don't know how to set it up correctly, but it's not like i'm going to use it for important work anyway..

[brynn]

Sorry for the late reply, and I think you're right. I tried using extension suggested by Brynn and have noticed that the gap is still there.

If you disable anti-aliasing, before you split apart the image, when you put it back together (with antialiasing still disabled), there will be no gap.  At least it did for me -- I tried it!