Scaling image depending on monitor size

Question

I'm looking to use a monitor as a "background" to trace onto and am a bit unsure of how scaling would affect the actual size of what is created.

Currently, we print off a pattern, and then use that pattern as a guide to "trace" things on top of it. We were thinking of using a computer monitor instead so we wouldn't have to waste so much paper (it gets ruined after each use). Can anyone shed some light on what I would have to look for as far as screen resolution, ppi, etc. if I want to make sure that the image that shows on the monitor would be the same exact size as the one printed on the paper? I currently have an .svg file of what needs to be printed, and am just wondering if I need to make sure that the ppi of the printer and the ppi of the monitor are the same...? Any help is greatly appreciated.

Answer 1

This is a tough one to answer succinctly. It depends somewhat on the content of your SVG file and what software produced it. And a lot on the monitor you choose.

Firstly (obviously) you would want to protect the monitor screen with something. Tracing directly off the LCD is likely to damage the screen.

As for SVG, there is not really a reliable way to get it to render at exactly life size. You can specify coordinates such as "1in" (1 inch) when defining shapes, but that is almost certainly not going to match a real inch exactly. Not by default anyway.

The reason is that in SVG, real world units such as inches are defined in terms of "CSS pixels" which are defined as 1/96 of an inch. Modern monitors are usually higher than 96 dpi and the resolution may not be consistent horizontally and vertically.

You can correct for it by tweaking the "width", "height", and "viewBox" attributes of your SVG. Getting that right will take a bit of effort and will depend on your monitor and the accuracy you need. Describing how to do it is a bit beyond the scope of a Stack Overflow answer.