Line pattern instead of grey-scale shadows?

I am trying to use Sketchup and Layout for design patent applications. The USPTO requires shading, to show 3D structure. The USPTO prefers that shading be done with a pattern of lines, with a line weight of 1 pt, rather than grey-scale shading. Why? They print submitted PDFs to paper, then they scan the printed paper to re-create a PDF (yes, this is true!). The printing/scanning process makes a mess of anything which is not a line with weight of 1 pt. It is really bizarre and painful, but they aren’t likely to change this system any time soon.

A number of the “Materials” in Sketchup would work for a line-based pattern to use in shading, but I need to apply the Material just to the shading. It seems like I should be able to do this by exporting the shading to some kind of layer or image and then converting this to a material, but I can’t figure it out. Can anyone help with this?? Thank you!

I think this is a thing for an image editor. Here’s a quick and dirty example:

I exported a Hidden Line image from SketchUp. This model was already set up to use a sketchy line style and I didn’t bother to change.

I turned on shadows and turned off edges and made another image export.

That shadows-only export was then manipulated to create a series of lines in the shadow areas and then combined with the lines only export.

An alternative that might work at least with simple projects is to use TIG’s Shadow Projector which will generate geometry of the shadows and then use textures. I’ve used this to good effect with very simple models but not with more complex things.

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Thanks, Dave. May I ask what you used as the image editor, to convert the shadows-only image? I have looked at Adobe products, but they are expensive and I hardly ever need everything else that they come with (so they are also confusing to use). Thanks for the suggestion!

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I used a freeware app called FotoSketcher. I’m not a huge fan of that particular filter but it was quick for the example. You could also use the shadow image as a mask for a line screen image. I expect you could find any number of them in an image search. I also used PaintDotNet as my image editor. Plenty of capability. Also available for free.

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Thanks so much for the pointers!

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This version pf “hatched” shadows was made by using a PNG image screen of white lines with transparent space in between as a watermark on top of the model.

Here I then overlaid this scene with the linework in LayOut:


Watermarks is where layers actually work as ’Adobe’ layers :wink:

Thanks Anssi and MikeWayzovski. I think I get what Anssi is saying regarding a mask of white lines. I’ll have to explore watermarks a bit. I hope this will work. It is so frustrating to me that I can get really close to what the USPTO wants using Sketchup and Layout, but then not quite. Thanks again, Martin

@DaveR , how did you manage to make the ground shadows darker than the others?

The mask can also be applied in LayOut:
background layer: scene with shadows only
middle layer: PNG screen,(patterned rectangle, one of the Tonal Patterns, White lines variety)
Top layer: Linework
I originally looked for a “woodcut” or “engraved” look.


I think that’s only because they fall on SketchUp’s ground and not faces. The Shadow-only image was done with the Face Style set to Monochrome. Much nicer shadows than in Hidden Line.

That looks really nice.