How to set perspective to a grid?

[psleighton]

Howdy! So I've got a hand-drawn pattern that I need to digitize, and for lack of a scanner at the moment, I took a picture of it on a 1"x1" grid (picture attached) intending to use those lines as the guide to square it up later in Inkscape. I've done that once before, I'd found a great tutorial for it, but now I can't remember how to do it, and I can't find the tutorial, and I've been googling various search terms to describe the problem for hours, with no luck. o___o

If anyone can point me to a tutorial for that (or just explain how, if that's easier), I would be very very grateful.

[brynn]

Welcome to the forum!

I don't completely understand what you want to do.  Now that you have the photo, do you have any way to load the photo into your computer?  Once you do that, then you can import it into Inkscape.  And Inkscape has many different kinds of grids.  So you could just use the rectangular grid and align the image to that.

Then you can use Inkscape tools to trace it.  If it needs to be so precise, I would use the Pen/Bezier tool to trace by hand.  If precision is not so important, you can auto-trace.

Well....actually I'm assuming when you say "digitize" you might mean that you need to vectorize it.  (Because if I'm not mistaken, cameras these days, produce digitized images.)

[psleighton]

I've got the image open in Inkscape now, and I'm good on vector tracing -- the problem is that the photo I took isn't exactly straight-on, so I need to stretch it in places (perspective adjustment?) so that the grid is squared off properly. This tutorial: https://www.lifewire.com/correcting-perspective-distortion-with-gimp-1701638 is exactly what I'm trying to do, but I can't find one that explains how to do it in Inkscape. =/

[brynn]

Oh gosh!  I've never tried anything like that with Inkscape.  I actually don't think.....  Well first, let me get some clarification.

What is it that you want to adjust?  If you want to adjust the edges of the paper to be square, you would have to use GIMP.  Because the edges of the paper are part of the photo, and you won't actually be tracing that, right?  And besides, Inkscape can't apply perspective to an imported raster image.

Or do you want to trace the drawing, and then adjust that?

Inkscape's perspective tool is Extensions menu > Modify Path > Perspective.  It only works on vector paths.

[brynn]

What if you adjust the photo in GIMP first, and then import into Inkscape?

[psleighton]

Huh, I could have sworn the tutorial I saw before had devised a way to stretch the raster image. But you've given me good options though -- it had not occurred to me to trace the pattern first and then correct the distortion afterward, although it should have. XD

Thanks! You have answered my question.

[Lazur]

Inkscape has limited options on dealing with raster images that way.
There is a perspective path effect that can distort paths -but not raster images.
That is an algorithm to modify vector elements, whereas distorting a raster image needs a filter. That is theoretically possible in inkscape but nowhere close to practical use.
Better use gimp beforehand to distort&clean up the photograph.
(By the way the grid isn't necessary if the drawing is on a standard sized sheet of paper.)

[psleighton]

I put it on the grid out of habit, because usually I do this for pattern pieces that are already cut out.

In any case, am taking the advice and downloading gimp now.