Can't set Document Properties as Expected

[Agrajag]

I have an SVG of a template for a different playing card size and no matter what I do, I cannot manually set the document size to match it. I have NO idea what's going on.

The size is supposed to be 750 pixels by 1125 pixels. But when I choose "px" and set that size it creates a page that's many times larger than the SVG (or PNG as the source for this has both file types to use in a template).

It can also be 2.25" x 3.5" so I set the document to "in" and set those settings and, again, it creates a Page that's many times larger than the file. The document size seems to have no connection to reality as far as I can see. In my existing cards (which I used a different template for of a different size), those also do not correlate to the template size for that size (63mmx88mm).

When I use File Explorer to check the file size of the PNG template file it reports it as expected: 750px by 1125px. As noted, however, when I load it into a Page it's tiny compared to anything I set.

What's going on?

[brynn]

It could be you have the Scale set wrong.  After you set the Display Units, what value do you see in the Scale setting?

Or it could be you have the control bar for the Selection tool using different units than the Display Units.  It sounds more like this might be the problem.  But it's really hard to say.

If you'd like us to have a look, please share an SVG file which is having the problem.

[Agrajag]

In all cases the Scale says 1.00000

The example case is to open Inkscape fresh. There you find an empty page. Select File, Document Properties and then try to set the properties. I then import the PNG template file and it SHOULD be exactly the same size as the page, but it isn't for me. It's a fraction of the size.

[brynn]

Hhmm, I just thought of another possibility that didn't occur to me before.  When you open Inkscape for the very first time (for some reason which seems bizarre to me) it's at 35% zoom.  If you've never changed the zoom level, then you're probably still seeing everything at 35%.  But I have to think you must have zoomed by now.  You've been using Inkscape for a little while now, right?

But when you say

In all cases the Scale says 1.00000

it makes me think that Scale setting is the culprit.  I know, it's confusing as all get-out.  (to use an old expression, which I haven't heard for ages)  But here's the deal.

Ok, the Scale setting should change (is supposed to change) whenever you change the Display Units.  This is normal (although in my opinion, it's confusing for most users and should be hidden).  Here's how to set it and use it properly:

1 -- Set the Display Units for pixels
2 -- Set the Scale for 1.0

Now, the Scale setting is correct.  From here, never touch the Scale again, unless you've figured out why it's behaving this way (and I certainly don't understand why myself) and you want to use it for some reason.

Yes, whenever you change the Display Units, that Scale setting will change.  But now, it will change itself in whatever way it needs to, to keep your document measurements correct.  So you just have to know that it will change, and as long as it always says 1.0 when you switch it to pixels, you know it's correct, no matter which units you choose and use.

I know it's confusing, and as I said, I don't understand it myself.  But unfortunately, that's what developers did, and at least for now, we pretty much have to live with it.

So, after you do the 2 steps above, don't touch the Scale setting again, and everything will be fine.  No matter which units you use (and no matter what the Scale setting changes to) your measurements will be correct.

[Agrajag]

Okay, I think I have an answer for part of this and it's DPI.

Now that I did the above (thanks Brynn), my settings seem accurate. I then imported the 750 by 1125 px PNG template and it was still a fraction of the size of the page and the toolbar showed is as something like 240 by 360. So then I remembered that all this time when I import a PNG I leave all the settings default, which has "worked" all this time. The key setting was getting the DPI "From file" instead of selecting "Default import resolution". Once I selected the latter the PNG came in at exactly the right size. Obviously the DPI of the Document Page and the DPI of the PNG are different. I think I've been getting "around" this by the way I Export. When I export I force the the export to be the correct size regardless of the size of the Document itself which is apparently at the perfect scale to fit my export size.

[brynn]

Yes, as far as I know the DPI for importing or exporting PNGs is unrelated to the Scale setting in Document Properties.  DPI is only relevant for raster images or printing.  Pixels ("dots") are irrelevant for vector paths. 

The default DPI for PNG import or export is 96, and as long as you use that, the image will import or export at the same size (assuming you started with the Scale setting being correct).

Yes, both the Scale setting and the DPI for imports/exports can affect the size of the resulting image, but they are different things.  And I still think the Scale setting should be hidden from at least most users.  Hidden by an "Advanced" button, or something like that.