Measure a curved path

[SpongeBob]

Hi guys

I found out and use the combo of V/transform tool width/height values to figure out the "length" of fully horizontal/vertical lines. But how do I measure paths that are not horizontal/vertical and also curved lines/paths? I need lines to match in certain scenarios..

Best,

_Rupa_

[John Rostron]

For oblique straight lines, you can just use Pythagoras: hypotenuse^×=base^2 +upright^. Or in practice:

Diagonal=sqrt(X-difference^2+Y-difference^2)

To obtain the length of a curve is much more complex. You need to integrate along the curve defined by the Bezier splines. Not for the faint-hearted!

John

[SpongeBob]

I'm making garment patterns and for example, I need to match the front and the back seam curves..So I would need to measure these lines (at the very least - two nodes)..

How come there is no way in AD to know the lengths of lines and curves?

[John Rostron]

6 minutes ago, SpongeBob said:

How come there is no way in AD to know the lengths of lines and curves?

For the reason I mentioned earlier:

52 minutes ago, John Rostron said:

To obtain the length of a curve is much more complex. You need to integrate along the curve defined by the Bezier splines. Not for the faint-hearted!

I am not aware of any graphics/drawing program that will do this. You probably would need to use a more mathematically-inclined program, possibly Mathematica. Just to give you an indication of the complexity involved, look at this page. At the least, you would need to export the co-ordinates of the curve in question. Not a simple task..

For your purposes. I would suggest that you:

1. create the two objects that need to match,
2. align  them so that the matching seams overlap at the start and finish,
3. adjust the handles so that the two curves are superimposed.

Hope this helps.

John

[SpongeBob]

Thanks for the suggestion, John..

In Illustrator, the document info panel, among other things, it also calculates the length of the selected path...That used to help..

I don't have Illustator now..

[John Rostron]

1 hour ago, SpongeBob said:

Thanks for the suggestion, John..

I would be interested to hear if my suggestion was any help.

1 hour ago, SpongeBob said:

In Illustrator, the document info panel, among other things, it also calculates the length of the selected path...That used to help..

By 'selected path' was that a single curved line along the length of the curve? Or was it the sum of a series of line segments comprising the path?

How would knowing the length of the curve (seam) help you create your pattern? I can see how it might help in knitting patterns, but not in cloth patterns.

John

[SpongeBob]

single ones and it also calculates along a series of nodes and line segments..It calculates based on all selected nodes and paths..please take a look at image 1..

For clothing patterns too, we need all edges to match with each other precisely...

Here's one example for where curves need to match for a clothing pattern..The sleeve curve has to match the front and back armhole of a bodice pattern..So in this case, i cannot superimpose the curves and ensure both curves are of the same length..Unless there is reason (ex.,for ease, other design features) for a difference to exist, all joining parts should precisely match..

 

[SpongeBob]

[John Rostron]

You could only do this using Affinity if there was some way of exporting the co-ordinates of a series of nodes. In that case, you could easily calculate the length using a simple spreadsheet. Perhaps you should submit a Feature Request  for Designer in that Forum.

An alternative that occurs to me is to copy the necessary nodes from one object to another.

I still think that to superimpose the edges would give you sufficient accuracy. I suspect that this would be as accurate (if not more accurate) that the accuracy of an end-user wielding a pair of scissors. I have no personal experience of dressmaking/tailoring but I have watched my wife and my mother-in-law do so.

John

[SpongeBob]

1 hour ago, John Rostron said:

you should submit a Feature Request  for Designer in that Forum.

Yeah I will be posting it soon; it is a much needed feature I think. Several others also seem to need it..

YepFor almost straight but not straight curves, I do copy the paths and superimpose them and make the best of it...

Also, I just use an actual measuring tape, place it on the screen, measure the first curve and in that same zoom %, I mark and measure the other curve..

I tried this last night and I find that this actually makes things faster for me..

 

[Gear maker]

SpongeBob, I don't know how accurate a measurement you need.  But a trick I have used to get a fair measurement of the length of curves in AD is to use the dashed line.  I have found that the following setting will position the dashes at 1" intervals.  So then I just count the dashes and estimate any partials.  Not the greatest, but it gives me a measurement probably to the closest 1/4".  Hint: enter the stroke width as a number instead of using the slide bar, the dash interval is very dependent upon the stroke width.  With a little playing you can find many combinations of dashed sizes that will give an interval that is usable to whatever scale is needed.  Start counting from the red node and the first dash is number zero.  So in the example below the lines total just shy of 18".

[John Rostron]

@Gear maker, a nice bit of lateral thinking.

John

[firstdefence]

2 hours ago, Gear maker said:

SpongeBob, I don't know how accurate a measurement you need.  But a trick I have used to get a fair measurement of the length of curves in AD is to use the dashed line.  I have found that the following setting will position the dashes at 1" intervals.  So then I just count the dashes and estimate any partials.  Not the greatest, but it gives me a measurement probably to the closest 1/4".  Hint: enter the stroke width as a number instead of using the slide bar, the dash interval is very dependent upon the stroke width.  With a little playing you can find many combinations of dashed sizes that will give an interval that is usable to whatever scale is needed.  Start counting from the red node and the first dash is number zero.  So in the example below the lines total just shy of 18".

I started tinkering and 1 millimetre = 2.83465 pt approx

So, this might be slightly off but if you draw a line 100mm long you will get 20 dashes with the setting below, I made the dashes 4.95mm long taking into consideration the minimum space allowed 0.05mm, it's pretty bang on too.

 

[Gear maker]

FYI other points I have identified for measuring:

1 1 0 0   36pt = 1" between dashes

1 1 0 0   18pt = 1/2"

1 1 0 0   12pt = 1/3"

1 1 0 0   9pt = 1/4"

1 1 0 0   4.5pt = 1/8"

1 2 0 0   24pt  = 1"

1 2 0 0   12pt  = 1/2"

1 2 0 0   8pt  = 1/3"

1 2 0 0   6pt  = 1/4"

1 2 0 0   3pt  = 1/8"

1 3 0 0   36pt  = 2"

1 3 0 0   18pt  = 1"

1 3 0 0   9pt  = 1/2”

1 3 0 0   4.5pt  = 1/4”

1 4 0 0   29pt  = 2”

1 4 0 0   14.4pt  = 1”

I don't know if it will be different with a retinal display.

[firstdefence]

Who needs complex math when you have the GMDS (Gear Maker Dash System)  liking the notation too

1 1 0 0  14.17pt = 5mm

[Gear maker]

2 minutes ago, firstdefence said:

Who needs complex math when you have the GMDS (Gear Maker Dash System) 

Hey I like it! Good one. 

[gdenby]

Something I've run across that helps the estimation. After defining the stroke, dash size and gap, expand the stroke, and divide. There will be a count of the new "dash" object. While not exact, as there may be fractional gap lengths, one can get fairly close. See attached, dash - 1 pt, gap = 4, so at least 13.935 cm

[PixelPest]

On 7/6/2019 at 5:56 PM, John Rostron said:

I am not aware of any graphics/drawing program that will do this.

Inkscape will do along other visualisations of shapes.

[Gear maker]

32 minutes ago, gdenby said:

Something I've run across that helps the estimation. After defining the stroke, dash size and gap, expand the stroke, and divide. There will be a count of the new "dash" object. While not exact, as there may be fractional gap lengths, one can get fairly close. See attached, dash - 1 pt, gap = 4, so at least 13.935 cm

gdenby, good idea.  Easier than counting the dashes.  The user must remember to always subtract 1 from the count and then add back any partial spacing as the fraction.

[Old Bruce]

1 hour ago, gdenby said:

Something I've run across that helps the estimation. After defining the stroke, dash size and gap, expand the stroke, and divide. There will be a count of the new "dash" object. While not exact, as there may be fractional gap lengths, one can get fairly close. See attached, dash - 1 pt, gap = 4, so at least 13.935 cm

It may be be safer to copy and make New Document from Clipboard then expand the stroke and divide, and then just Select All. Just 2¢ in an attempt to prevent frustration with Undo, Undo, Undo etc.

[thomaso]

On 7/6/2019 at 4:42 PM, SpongeBob said:

how do I measure paths that are not horizontal/vertical and also curved lines/paths?

Workaround: In case you can split your workflow into Drawing the shapes and Designing the pattern, then a CAD construction application might be useful. For construction software it is an requirement to know all sorts of measurements and in high precision. 2D apps are easier to handle than 3D, some are free. Some are especially for clothing pattern.

[PixelPest]

Once again: Inkscape will do:

Cheers

[DianeF]

I am pretty sure that Patternmaster Boutique (from Wild Ginger) also has the capacity to measure arc lengths. Since this is specifically a pattern making program it is set up to measure all components of pattern pieces. It has a pattern editor component that is really excellent and allows for detailed customization of pattern pieces. The only drawback of the program, and one reason that I don't use it much any more, is that it is available only for Windows computers, not Macs.

[SpongeBob]

@Gear maker, and all of you, thank you so much!

I tried out the GearMakerDashSystem and it is helping me with some of the things I'm doing!

 

[John Rostron]

On 7/6/2019 at 3:54 PM, John Rostron said:

To obtain the length of a curve is much more complex. You need to integrate along the curve defined by the Bezier splines. Not for the faint-hearted!

I have been trying to  rise to this challenge, albeit in a half-hour chunks of php programming here and there when I had a moment.

I have written a PHP script embedded in a web page that looks at a SVG file and extracts paths, and calculates the length of each segment in the path (a segment is a stretch between two nodes).The units are the units defined within the SVG file. I'm not sure how they would map into actual units in a Designer file.

To measure the length along a curve, it is broken up into a series of arcs each of which is approximated by a line. By default it uses 20 such arcs, which seems to give adequate accuracy.

I would welcome any feedback on this script, as well as the user interface. On my PC, Kaspersky seems to inject its own components which seem to clobber my careful styling of the interface.

John