Sizing in Inkscape

Inkscape and AI have different native resolutions, so images *look like* they are different sizes.

I would guess that both Inkscape and AI report the image as the same size.

That doesn't really help me.

Well, I apologize. I guess I don't understand exactly what you need.

The development version has the new Measurement tool, as far as I know. I don't have the exact link at the moment, but you can find it through inkscape.org.

I guess I don't understand "resolution" when it comes to a vector drawing. That should only make a difference if I am rasterizing it.

If I make a box 1"x 1" in Inkscape, shouldn't be 1"x 1" in Adobe Illustrator as well?

I would like to use Inkscape because it doesn't have the size limitation that Illustrator has, and I am frequently designing for large areas. I have to export the files though because the vinyl cutting software only accepts Illustrator 3 format. I want to be sure the size of my drawing isn't changing through this process.

Thanks.

The image size does not change from one program to another, unless you manually change it.

The native resolution that I'm talking about is not the same resolution that you talk about with printing, or with raster images. The native resolution is how the programs create the display that you see on the screen. The display on the screen can only be rasterized, because that display is still mapped to pixels. Even though it is a vector image, it can only be displayed by being mapped to the pixels.

Since I don't have AI, I have no way of investigating for myself. If you open the same image, in Inkscape and in AI, and you look up the image size (not by looking at the rulers), I expect they should report the same size. And I expect that as long as you don't tamper with the image size, then the image saved in Inkscape should still be the same size as the image saved in AI (although they may look like they are different sizes).

If you look at the same image on a computer with a different screen resolution, I imagine it will look different still. For example, I learned a year or 2 ago, that if I make an image in Inkscape, let's say the same 1 x 1" square, and hold a ruler up to the screen, it's something quite less than an inch. And that's due to how my compter screen creates the display. I'm not sure if I still have it, but at that time, someone showed me a site where you could calculate how various screen resolutions affect the true size of an image.

But since I can't investigate for myself, I can't give you many details. And I could be totally wrong. I do know for a fact that Inkscape and AI have different native resolutions. That, I do know for a fact. But it makes sense to me that the image size shouldn't change just by loading it into another program.

Since you have AI, maybe you could do a test. But instead of cutting out of vinyl, maybe just try printing....although I guess I'm not sure how the printer's resolution would affect such a test.

That's about all I can say. Hopefully someone who knows more about it can explain it better.

Well, I am not talking about holding a ruler up to the screen. I am only concerned with the output to a printer or plotter, and the size measured by the program's rulers. If I need my logo to be 2' x 5', I'm expecting that if I create it at that size in Inkscape, it retain that size if I open it up in AI, or Photoshop (even though Photoshop allows me to change the size I rasterize at, the size it defaults to should match the size I created it at)

After more experimentation, I discovered that Photoshop has a maximum width of 106.666 in. which was causing the problem I was seeing, since my drawing is larger than that. Photoshop was reducing the size of the drawing to fit within that.

The other thing that I noticed is that when I create a rectangle and type in the size, for instance 10" x 10", what I actually get is a rectangle that measures 12.7" x 12.7". I am not sure why this happens, but it was leading me to believe that the rulers were not reporting accurate measurements. I have my document default units set to inches.

Donald Drennan: "The other thing that I noticed is that when I create a rectangle and type in the size, for instance 10" x 10", what I actually get is a rectangle that measures 12.7" x 12.7". I am not sure why this happens, but it was leading me to believe that the rulers were not reporting accurate measurements. I have my document default units set to inches."

Well, the rulers indeed are not accurate! They are just a guide, rather than a measurement tool. (Even grids and guides are not visually accurate, although they can be precisely set.)

Instead, you should use the H and W values shown in the Selection tool control bar.

The H and W values on the control bar include the width of the stroke. (You could try widening the stroke and observing the change of the H and W values, to see.) I might guess that you drew a rectangle with a stroke, and with or without a fill. If that's the case, (and you got 12.7" from the control bar) that probably accounts for the difference. Instead, you could try removing the stroke, as long as the rectangle has a fill color....even white. (If it didn't have a fill color, it would be hard to select.) Then the size reported on the control bar will be the true size of the path.

I'm not familiar with vinyl cutting soft- or hardware. If it cuts along a path, then the stroke might not be necessary. However, some of those home craft cutter machines do require that the path be stroked, and some apparently the stroke has to be a certain width and color. So you'll need to know how your vinyl cutter works, as far as knowing whether to keep the path stroked or not, when you send it to be cut. If it does need to be stroked, you could do some simple math, to set the finished size of the cut vinyl. W and H will both have to be the stroke width x 2 larger than your intended finished size.

I'm not sure you mean this, but just to be clear I'm not holding a ruler up to the screen. I'm not sure what you mean by "visually accurate". They should at least be somewhat close. If they are off by a huge amount, I would consider that a problem.

What I meant was, I typed in 10" x 10" in the H and W values in the creation dialog box when I was creating the rectangle. Once I had created it, I looked at the H and W values (different than dialog box at creation time) and they read 12.7" x 12.7". I repeated these steps in another document and got different results, also inaccurate. I could not find any reason for this. My rectangle had no stroke on it and by the way, the vinyl cutting software requires that objects have a fill, but no stroke.

Yes, I realize you're not holding up a ruler to the screen. I just mentioned that when I was trying to explain what I meant by different resolutions affecting the true size (and how resolution matters to a vector image).

The rulers are close. For example, if you draw a rectangle and place it at x = 1 inch, then scroll the rectangle up near the horizontal ruler, it might not look like it's precisely on the 1 inch mark on the ruler. Especially at different zoom levels, the rulers (and grids and guides) are not accurate. By "visually accurate" I mean that grids and guides are like rulers. Even though you place an object precisely on a certain x,y coordinate, when you look at it next to guide or gridline which has the exact same x and/or y value, the object might not look like it's in the right place. But, if you've place the object using the X and Y fields (and H and W too) then that's exactly where that object is. It's just that the rulers, grids and guides might not look like they agree.

In the current development version, and in the next stable major version release (0.91), Inkscape will have a new renderer (the part of Inkscape which produces the display that you see on the screen). It's possible that some of the "visual inaccuracy" will be....at least improved. I honestly don't know if it will or not. But maybe it will?

Ok, before I comment further on the difference you're seeing in the size you originally set, and the size you see on the control bar (H and W), I need to be clear on where you originally set the size. You said "the H and W values in the creation dialog box" when you were creating the rectangle. Since you are so clear about saying "dialog box" I wonder if I may have misunderstood something. All this time, I've been thinking you're creating a rectangle using the Rectangle tool, which has no dialog box (at least not in the current stable version).

The Rectangle tool does have a control bar, which is different from the Selection tool control bar. That's what I thought you meant. But maybe I should ask how you are drawing the rectangle? For a minute I was thinking you might mean a text box. But it doesn't have a dialog either.

I agree that the difference you're seeing seems excessive. I thought it might be explainable by the rectangle having a stroke, but now I'm confused about how you're drawing the rectangle in the first place.

It might not matter, after I find out how you're making the rectangle. But you said your vinyl cutter needs fill but no stroke. So I guess you are drawing the rectangle with a fill and no stroke, right?

Since this is getting so involved, you're welcome to message me (click on my user name, then Contact This User). Maybe we can finish up a little more quickly. Although I'm happy to stay here, if you prefer.

Sorry, I wasn't using the proper terminology. Control bar is what I mean. Yes, the control bar for the rectangle tool doesn't match that of the selection tool. But I just did some more tests, and it seems to be peculiar to this one document, which came from Adobe Illustrator. If I create a new document, I don't have this problem. I'm still not sure why this is happening. I copied the drawing's content and pasted it into a new document and I don't get the same problem.

Donald Drennan: " I copied the drawing's content and pasted it into a new document and I don't get the same problem."

That's good news! .....Well, assuming it will be a satisfactory solution for you. Is there any reason why that can't be a long term solution?

I suppose it is a solution, but I would still be interested in knowing what the cause is. If it's a bug in Inkscape it should be noted and fixed.

Thanks!

Since copying the content and pasting into a fresh inkscape doc, solves the problem, it's reasonable to conclude that whatever is causing the problem comes from the Illustrator file.

I don't remember if you said what format the original file was, except that it came from Illustrator. If it was AI, perhaps it's something to do with that format. But even if it was SVG, it still carries with it the way Illustrator works.

I'm not an expert on the technical side of Inkscape, so I could be wrong about this. But I seriously doubt that compatibility with Illustrator will be of much concern to developers. At least not this issue. Actually you're lucky you were able to open it at all in Inkscape! I see messages all the time about people not being able to open Illustrator files in Inkscape.

However, since Inkscape is an open souce project, if you do feel that it should be considered a bug, you're welcome to submit a bug report. Just click "Bugs" in the header, to get to that section.