Hi guys, new forum member here. I have some experience with drawing with Inkscape but I am new to the complicated stuff, one of which seems to be the dimensioning tool.

I have a drawing of an object that I know its dimensions. How can I reset the dimensioning tool in Inkscape to measure areas and lengths based on this objects dimensions? I get totally different values.

I am referring to something along these lines:
1) I draw an object based on a blueprint; Inkscape's Measure Path is saying it's 61.27cm2 in area.
2) I say ok Inkscape this object is 10cm2 in area, calculate everything else based on this

Right now I make a drawing, I draw a ruler (literally) and I scale my other objects based on this dimensions. Then I know I have my proportions right. When I am to dimension everything with the use of the Measure Path, I get all the dimensions I want and then go to Excel and calculate the real dimensions based on the known size object. I then go back to Inkscape and replace every value with its real calculated one.

I know I can do this in LibreCad or other CAD software but I don't have there the freedom of Inkscape as an prototyping tool. I love the freedom of inkscape but I would like some way to finally constrain some shapes to different sizes before exporting them as SVG to import in LibreCad to refine. Then from 2D cad it goes to 3D cad and so on.

Please let me know if this is possible.
Thanks.

By "dimensioning tool" I guess you mean the new Measurement tool? (hmm, need new smiley icon)

I am referring to something along these lines:
1) I draw an object based on a blueprint; Inkscape's Measure Path is saying it's 61.27cm2 in area.
2) I say ok Inkscape this object is 10cm2 in area, calculate everything else based on this

No, Inkscape can't do that.

If I need to do something like that, I pretty much do the same thing. Except I just grab the Windows accessory calculator, because I never need that much detail for my hobby work.

When you go through this procedure to change the scale of 1 object, does everything in your drawing need to be changed by the same ratio? If that's the case, it might work better to use 1 object to calculate the correct ratio, and then Select All and scale the whole image to that new size. But if each object needs to be changed to different proportions, that won't work.

Hhmmm....when you say you draw an object based on a blueprint.... Are you taking the dimensions given in the blueprint and drawing the object more or less freehand? Or are you actually importing the blueprint, and more or less tracing over it? If you already have the dimensions before you draw it, I wonder if you couldn't just do the calculations first? Then you could draw it at the correct size, from the start (instead of drawing and then scaling it).

Well, I don't know much about engineering. I just know some basic math principles. So I'm just sort of thinking on my feet here. Actually this sounds like something Ragnar might be able to help with. Although I haven't seen him around the last week or so. But probably other members will have some more helpful info to share.

Good luck. I hope you can find some kind of routine that works.

I'd just set the document units to my preferred units (in, cm, etc.) and work as though I'm using CAD (albeit without the usual CAD tools).

Hi there,

you say you know the dimensions of an object, which are measured differently?
How can you tell it's not your drawing that is off scale?

Rectangles are the easiest to check.
Draw them with fill but no stroke -or set bounding box from visual to geometric,
then type in the right object sizes at the top and convert object to path before the extension.

Don't forget to add the same measures, practically everywhere -document base unit, size of your object, and extension's setting.


Focusing more on your two points, what does the blueprint cover?
For instance if that's a raster image, in it's original scale it has a 90 dpi resolution. If it is a scanned image based on a 300 dpi scan, measure should appear 3,333 times larger in the lengths.
Also if you not redraw the image based on the original blueprint's measures, but trace it over by the look, the measures will be off for some extent -no setting of a measure extension could correct that.

But 61,27 cm^2 vs. 10 cm^2 is quite large difference, probably your drawing needs to be scaled accordingly.
(10)^(0,5)/(61,27)^(0,5)=40,39950648% scaling on the size of the object (height or width), proportionally, should fix it.


In practice it can be a bit different, we should see the bigger picture of your workflow/file you working on.

Hi guys thanks for weighing in... all your answers helped once I've read them. I realized I should have started from the beginning with dimensions in mind which I didn't... I sketched and scaled and sketched more, until I realized that my drawing doesn't keep proportions. That's when I learned about the Measure Path extension and I started going backwards with the dimensioning.

@brynn: I realized at some point that I need to add an object of known dimensions (like a standard skate ball bearing or say an M8 bolt) and I needed re-scaling all my objects to match the proportionality. I used an imported blueprint and didn't care about actual dimensions as I did about proportionality. Then when I had my bearing in Inkscape (traced over) I wanted to scale it to its real dimensions so that inkscape and I aggree on that .

@Lazur URH: I have now set all my dimensions, Document Properties and Measure Path to mm.

@tylerdurden: yes that would work ok although I'd like to be able to enter those dimensions on the drawing itself, like CAD would do (I must say I don't know CAD, i've barely seen some youtube videos). It's quite annoying when you have to introduce dimensions for every object you draw to go back and forth to the top of the screen. But it's essential if one needs proportionality.

Thanks guys again and I hope I provided some answers that would make clearer what I wanted in the first place.