I have problem with : Tool Point at intersection of arc and line


#1

hello I would like help because I do not understand where the error is when I want to create the shoulder. I watched your videos but I can not find the mistake. thank you very much for your help

bonjour j’aimerais de l’aide car je ne comprends pas ou est l’erreur quand je veux creer l’epaule. jai regardé vos videos mais je ne trouve pas l’erreur. merci beaucoup poufr votre aide


#2

Probably your measurement is too small for this to work. The circle does not intersect with the line so the program places your point in the start position

Are you quite sure you are doing everything correct in terms of patternmaking method? It’s a very unusual way to find the shoulder point in my opinion


#3

I agree with @Krolich, but I’d like to see the actual pattern file to test it - if you can upload the .val and .vit file, please.

I tested it on one of my patterns in the way that you show in your video and this is what I get:


#4

image

I decided to try it too. It only intersects if I add correction for shoulder dart and even then the point (A135) is nowhere near the actual shoulder point (A13). This pattern is tested and fits perfectly, so my shoulder point is 100% in it’s rightful place :wink:


#5

Yes, I think 12.4cm is far short of the line indicated in the 1st part and is confusing things. That’s why I asked for the .val & .vit files so that I could test it. I know I had a similar problem making sleeves on one of my learning patterns. It kept on placing the point to the right of the pivot point instead of to the left. I ended up placing a small arc over the line on the left side and used the Point Intersect Arc and Axis to get it in the right place:

image


#6

I have had the same problem and verified that the tool does not behave as expected in some situations. Grace, here is a .val and .vit file to demonstrate the problem and in this particular case I solved it by correcting what seemed like a very minor error which caused the length of the intersect to fall short of the line.

Leilani_Dress_3.val (44.9 KB) kim-mannequin.vit (1.8 KB) Leilani_full_size_mannequin.vit (2.0 KB)


#7

Thanks, @kmf. :slight_smile: I think that’s the exact problem that @clubcouturemg is experiencing, although, I think 12.4cm is a pretty reasonable shoulder measurement, I think the line going from A2 downwards should be a bit closer or the neck width (line A to A5) should be a bit wider. The tool behaves badly when it can’t reach its destination. :slight_smile:


#8

thanks you @Grace, @kmf, @Krolich to help me soo quickly. I made a big mistake and I deleted the file. I do not have it anymore. it’s not the method I normally use but I wanted to learn by following the example in the video valentina project. I will start again with my old method but I will follow the evolutions and your solutions to learn more. thank you very much for your very warm welcome


#9

I found a mistake in the way the pattern was drafted. it was a small mistake, but correcting it allowed the pattern to work with my measurements. I am uploading the corrected dress pattern. I will also post a few screenshots of my process in finding the error.

THERE IS ACTUALLY A BUG in the way the tool works. If the radius line from the center of the arc would not reach the line you are attempting to intersect, it will produce the wrong point. I will create an issue for that bug, but meanwhile it may be reasonable to add a tiny bit to that radius to make it work.

In the case of this particular pattern, the mistake was that the formula to place point BH on the back draft was Line_A_H + (shoulder_tip_to_shoulder_tip_b - shoulder_tip_to_shoulder_tip_f)/4.

The correct formula was (0.22 neck_circ) + (shoulder_tip_to_shoulder_tip_b - shoulder_tip_to_shoulder_tip_f)/2*.

I replaced Line_A_H with its formula as used in the front draft which was (0.22* neck_circ) I read this as one quarter of the neck circumference plus a factor to allow for the patternmaking method. To be precise it probably should not be exactly the same for the back of the neck in some people. This change did not affect the drawing of the pattern.

I replaced the “/4” with “/2” in the second part of the formula: giving the corrected formula that I used. I read this to be one (imprecise) fourth of the neck circumference PLUS the difference between the back and the front measurements of shoulder_tip_to_shoulder_tip. I believe it is incorrect to divide by 4 since the measurements being subtracted are both half body measurements. Therefore dividing by 2 will give the quarter body measurement which I think is correct. It is an almost imperceptable difference in the appearance of the pattern with the “manequin” measurements and it made a difference with my own measurements of letting the pattern draw correctly.Leilani_Dress_Kim.val (44.9 KB)


#10

THIS IS HOW IT LOOKS WITH THE BUG SHOWINGkim-distorted-shoulder

THIS IS THE ORIGINAL FORMULA THAT EXPOSED THE BUG IN THE INTERSECT ARC AND LINE TOOLoriginal-point-BH

THIS IS THE ORIGINAL POINT USED AS THE CENTER OF THE ARC (length was copied from front piece) original-point-BJ

original-point-H

fixed-point-BH

kim-dress-back


#11

Oh, wow! I don’t know if I would’ve found that one :frowning: Very well done, @kmf :slight_smile:


#12

if you play with the measurements it will become apparent. the “mannequin measurements” are quite symmetrical but most humans are not. The differences in a real person such as the difference between the shoulder span measured from the front or measured from the back will show up. One of the things I like to do to test whether a pattern is truly resizable is to load several sets of measurements and watch how it behaves.


#13

You guys rock.