Full Version: leader lines for technical illustration

I've been experimenting with different styles of leader lines trying to find one that is as clear as possible about what it's pointing at in a perspective drawing while also distracting minimally from the perspective. The best I've come up with is a line that's normal to the surface and terminates at the surface in object space and then curves to be either vertical or horizontal in paper space:



I make these by drawing a little stub line normal to the surface in 3D, save as SVG, import the SVG back into MoI, trace over the stub with a polyline snapping to the end and then to horizontal or vertical, construct a constant distance fillet at the corner, and finally save as SVG again.

Does anyone have ideas for a different style of leader that's just as good, but easier to make, or an easier process for making this style?

- Peer

Image Attachments:
leaders.png 

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That seems very clear to me. The SVG export/import is a welcome addition.

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I had a quick crack at it. I took your image, edited out the lines (keeping the end points) and brought it into Inkscape.

I just traced from the letter to the end point by eye. Trusting my gut, basically. I didn't end up with the completely accurate line orientation your process creates, but I wasn't jumping back and forth between programs either.

First, I just created a black poly-line and threw a white line behind it with a wider stroke. This looked alright to me, but I felt it might need to be a bit clearer.



Second, I added little dots on the ends to help draw the eye to the target. Not bad but, I noticed that your model is very geometric. Curves stand out as a nice contrast to that and I think I understood why you chose to round the corners.



Third, I decided to round off the corners with Inkscape's "Corner" Path Effect. I added it individually to each line and tweaked only parameter until the curve looked good enough. However, I could have "Combined" all the paths into one and then added the Corner Effect to tweak them all at once and then individually, saving a lot of clicks. Again, I "Duplicated" the lines and put the white lines behind again.



This explains how to do the cornering in Inkscape. https://superuser.com/questions/640954/inkscape-rounding-corners-of-shapes

You can go too far or not enough. It's always a judgment call. I'm kind of partial to the second one I did.

Anyway, I hope this helps you. Sometimes it's good to see what you don't like, as well, to help confirm the path you are on.

I also kept everything as black and white. I assume that was a conscious choice on your part, but colours or shades of grey can help too.

Good luck with your schematics, pressure.

EDIT:



I decided to keep all cornering to the same radius to provide more consistency with the feel of it. Coincidentally, this was the quickest way to do the rounded corners and looks better, in my opinion. I better leave well enough alone now. ;-)

Quick Tip #1: Holding the CTRL key in Inkscape while drawing a line locks it to even degree constraints. This makes it so easy to draw perfectly straight lines and works when moving points within a line, as well.

Quick Tip #2: Because the cornering effect is a procedural thing, the original points of the poly-line still exist and you can move them around and the cornering is automatically recalculated.

Image Attachments:
leader-design-2.png  leader-design-3.png  leader-design-4.png  leader-design.png 

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Hi Cody,

Thank you for working on this! I really like your dots. And sorry for my slow reply: I was travelling.

That's a good point about using color/value to separate leader lines from object lines, though can't really do it in this case since these are for print and I'm trying to avoid fuzziness from halftoning. But I'll try that next time I do a drawing for digital-only.

I actually did try making the radii in vector graphics initially. The problem I ran into is that using one radius didn't look the same on acute and obtuse angles, but one fillet distance does:


I don't know how to make a constant distance fillet in Inkscape, Illustrator, etc. so that's why I did that step in MoI rather than eyeballing each one.

Anyway, I really appreciate your help and am going to borrow your dots :)

- Peer

Image Attachments:
radius_vs_distance.png 

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You're very welcome, Peer.

I had fun making those samples. It's all good, man. :-)

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