How do I create a scale drawing from an image?

[Smoo]

Hi all, I'm new to the forum and new to Gimp.

I'm a blacksmith and fabricator, and what I want to do is print life size drawings of objects from images so that I can use them as templates for cutting steel etc..

So lets say I wanted to make a replica of a knife from a picture. I import the image, cut round the knife, re-orientate it and correct perspective(if necessary), re-scale it to real life dimensions, create a line drawing version and print it out. I also need to be able to print things which cover more than one page for large objects, even things which could be a metre long or more.

I had a bit of a go but quickly started to come unstuck. I was able to draw round the knife, but I couldn't make it a new layer of it's own. Also when I rotated it, the top and bottom were outside of the layer boundry and I couldn't figure out how to stop it cropping the image.

I can probably do the line drawing bit ok. Unless I need specific angles and symmetry. But I'll figure that out when it comes up.

If anyone can point me in the right direction that'll be awsome!

Cheers

[rich2005]

I would stick to basics.

1. Make a canvas in multiples of a paper size. I used 3 x A4. No need for wonderful quality so set to say 100 ppi.

2. Put your image on that and scale to suit. Draw round it (on a new layer)

3. Make guides at one-third points to divide back to individual sheets.

4. Use Image -> Transform -> Guillotine and that will chop up into new images at the guides.

5. Packing in for the day, so here is a 5 minute video with some pointers in it to get you started

https://youtu.be/okMKmOs9ZV4

[Ofnuts]

If things look cropped after a rotation, use Image>Fit canvas to layers to enlarge the canvas to uncover the hidden parts.

If you draw around the knife create a new layer (with transparent background) and draw on it (as if you were using tracing paper). Then you can hide the original layer with the object and can print just the line drawing.

But I strongly suggest that you trace your lines using the path editor. The paths you create that way are just "virtual" lines (thin blue/red lines). To make the drawing from them: add a new (transparent) layer and Edit>Stroke path (use "Line" mode).

[Smoo]

Thanks for the replies! Very useful video rich, thanks. That will defo get me started. Will have a go and see what I can do.

Cheers