Very specific simple question (illustrated) about creating surfaces

MacBook Pro, M1 (Apple silicon), loaded, Ventura 13.6, large external monitor. Intermediate-advanced photoshop and illustrator user. I am trying to evaluate whether sketchup will be able to carry out the task discussed below. If so, I will quickly try a free trial to make sure I can actually use sketchup, and then will purchase the pro version. (A quick answer would be greatly appreciated so I can take advantage of the current discount.)

Can sketchup (along with plugins) create a surface from the two connected completely distorted boxes, as illustrated below?

There are three distorted rectangles - black, red, green. Rectangle (planar) faces are parallel. Each rectangle is in an xy plane, arranged along the negative z axis. Each rectangle has NO symmetry. Distances (along z) between successive (distorted) rectangles are equal (units irrelevant). Connecting lines (blue and violet) are drawn from the corners of one rectangle to the next one. This gives two distorted 3D boxes joined at a common face (the common face is the red rectangle).

This figure has an external surface. Can sketchup (with plugins) create this surface, and can I make that surface an arbitrary color?

I have viewed similar questions in this forum, but the planar objects are always symmetric in some way. My surface rectangles have no symmetry.

I wanted to make sure about the simpler case before introducing a more complicated one. For a more complicated version, each rectangle becomes an arbitrary planar object bounded by a continuous closed non-self-intersecting line (not in general convex). So in this example, there are three bounded planar objects - black, red, green. There would be multiple lines from one planar object to the next one, which would delineate a more complicated surface.

Again, could sketchup create this surface?

Thanks in advance.


you could hand stitch, or use a plugin called curviloft.

gimme a minute

so I made the 3 shapes

then I stacked them.

and then tadaaaam

I used an extension to divide all the lines, then used another (curviloft) to automatically stitch the gaps.

(and the end result is a solid, so I could print it in 3d for example)

Thanks. Can it be done without plugins, by drawing one rectangle on top of another (both in xy plane) and then extruding the “top one”? Will this work with arbitrary planar shapes?

I m sure you will be able to do this, with or without extensions and with any surface.
Something lick this bad sample?

yes, like that. it’s called stitching. i’s long and boring, plugins makes it trivial and really quick.

yep, including curves, if you do it by hand, it’s just gonna be long. and boring. I insist on the boring part.

Yes, but note that the sides of the shape @ateliernab drew are faceted now and not planar per side. The more you subdivide the lines of the primary shapes the finer you can make these ‘side’ surfaces. You could make them very crude by simply connecting a few corners (will look like a 90s video game) or you can make them refined by having more triangulation / facets on those sides.

See this SU file for ideas.

Distorted solid.skp (226.5 KB)

Thanks, bmike.

The whole purpose here is to allow me to visualize (in my head, away from the computer) what is an organic complicated 3D structure (definitely NOT architecture), and without spending thousands of dollars. While I have difficulty visualizing a fully-rendered 3D scene (in my head), I have much less difficulty with a “90s video game” schematic (or abstracted) version. So that might be just the thing.

What I’m doing is trying to stitch 5 - 20 portions of coronal brain sections (which are planar) into a 3D conceptual object - not necessarily a super-accurate “scene”, but something that allows me to roughly visualize connectivity, relative size, neighborhoods, and basic shape.

“Roughly” is the name of the game.

So perfect. Thanks.

I might be way off here but wouldn’t subD work in this situation?

To make soft shapes and smooth out the final product, sure.

But OP has shapes already that he wants to connect - imagine slices of bread that need the surfaces between infilled.

I’d look at Curviloft but it can be done by hand as shown.

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This is the crudest way to do it - connecting the corners to split the connecting surfaces so they create planes. If you do it by hand you can subdivide the shapes as @ateliernab showed before stitching (so each reference shape has the same number of subdivisions)_or you can go from end points, mid points, etc…

And then picking midpoints and triangulating from there… FWIW the other method shown here is nicer… but these are examples of how crude it can get.

OK, this is great!! Thank you all!

I believe I can do what I want, based on the examples, and presumably there are lots of variations. In addition, I saw some tutorials on plugins such as vertex tools, subD (as recommended), soapskin, curviloft, quadface tools, and there may be more. These are likely to be applicable to my project.

Based on all these responses, I will go ahead and purchase sketchup.

I would like to note that almost all tutorials/video examples which I have seen (and I certainly have not seen everything) use either very symmetric situations or else apply extrusions from a grid or from symmetric objects, which, in real situations, might require a considerable amount of post-extrusion sculpting. I think two reasons are that video examples go fast, and they illustrate basic functionality.

It certainly would be nice (at least for me - not a fan of symmetry) to have more general video examples - a metaphor would be abstract art vs realistic art. (semi-abstract figurative Picasso vs Ingres.) There is, in the end, a huge difference in technique.

Thanks again.

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