Outer Border Trace

[Don Cheke]

I know that some of you use Adobe Illustrator. Do you know if there is a way to easily find and outline a collection of lines that make up an illustration?

In this example, I printed my suppress hidden line 3D model to PDF (essentially a 2D illustration now) and opened in Illustrator. I could find no easy method to select and outline the outer perimeter. What I did to get the outer perimeter was to render my 3d model without lights and materials so it rendered as a black silhouette. I open the rendered image in Illustrator and used the trace functions to create a vector outline. I then just stacked the results an assigned a thicker stroke to the trace.

[JamesProvost]

I'm assuming that the hidden line export doesn't include fills for the object?

If that's the case, here's a quick and dirty way to do it:

1. Make a copy of the lines layer (Option/Alt drag the layer to the Create New Layer button) then hide the original layer.
2. Select All. Object > Live Paint > Make.
3. Make sure you have a fill color selected.
4. Use the Live Paint Bucket tool (K) to paint inside the lines.
5. Select All. Object > Live Paint > Expand.
6. Get rid of the strokes. Select a stroke (Direct Selection tool, the white arrow, is easiest because it will be grouped). Select > Same > Stroke Color. Delete.
7. Select All. Window > Pathfinder. Unite button (top left).
8. Set your desired Stroke/Fill
9. Move your new outline layer below your original line layer

You could also try the Shape Builder Tool. After step 1, select all your artwork, then the Shape Builder (Shift + M) and drag a marquee (hold Shift) over the whole object. If it gets everything, you can continue from step 8.

[Don Cheke]

Thanks James,

I had tried both methods, but I didn't know how to use live paint. Following your instructions, I was able to follow through.

Shape Builder didn't like all the lines in this model, so it took a very long time and missed 75% of the model. But is is definitely something to try again.

I will be sure to bookmark this post for future reference.

Again, thanks for you help.

[JamesProvost]

If you figure out an easier way, I'd love to hear about it.