Vault modelling - gaps between separate surfaces


We are facing the following issue: me and my colleagues are working on a renovation of a historic building. Generally we are working in ARCHICAD, but for the vaults and other curved shapes (wall niches) we are using Rhino. We merge or hotlink the Rhino .3dm model (we use Rhino 6, but we have to export back to Rhino 5 for AC) to our host .pln file. In the end we send our models to Cinema4D for rendering.

In the renders as you can see in the following image, the surfaces do not align perfectly, there are gaps inbetween (segmentation, perhaps). This is what we would like to eliminate.

This first image is an initial HDRi lit image (C4D + Corona).

Rhino 6 shaded viewport zoomed in:

Rhino 6 rendered viewport:

We model these shapes in the following way:

  1. For workflow reasons we draw and model the plans and basic spatial elements in ARCHICAD, which we export as a DWG to Rhino.
  2. Import the DWG to Rhino, select the curves that are drawn in plan (the main curves are rotated into the floor plan) and using the interior wall edge we rotate them vertically, position the crossing arches to the mid-points, check the vertical positions according to the survey. So we end up with this:
  3. Rebuild the curves to an equal number of points (usually around 25), degree=3.
  4. As the shapes are quite irregular, we use NetworkSrf a lot, even for fragments of the vaults. The main vaults are usually modelled this way. PlanarSrf is used for the walls and Loft for the wall niches.
  5. We use the base curves for each surface, as we thought it provides similar topology and segmentation, no surface edges were used in the individual surface creation. Initially it looked okay, from a distance like this:
  6. Yet we have the small gaps as you can see, and we hope to have a visually pleasing, continuous structure even when taking a closer look. Is there a way to align the segmentation or to fill them as a quick fix?:slight_smile:

The idea was to create the bounding surface only in Rhino, and use that for interior renderings, but this problem prevents us from creating the imagery.:frowning:

I don’t think that this is related to hardware of software problems, I guess this is more like a “user error” kind of thing from our side, nonetheless:
HW: various Macs / SW: macOS 13.6 - 15.4, ARCHICAD 22 INT b6025, Rhino 6 6.25.20114.03572

Any suggestions? Do we mess up the base curves, or some settings for the surfaces? The most deviation seems to occur between the networkSrf and the planarSrf parts.
I’ve cleaned up a bit our base Rhino file, and attached it to my post, please take a look at it.


200518_vault issue_discourse.3dm (7.6 MB)

Based on your images, I can’t tell if you have poorly fitting surfaces, or poorly matched render meshes because the surfaces are not Joined.
If they are Joined, then there are tools to close up the faceted gaps across surface edges. IF they are not joined, you get what you images show.

Don’t confuse the render mesh needed for shading with the actual surface edges shown by edge curves.

See if this explains what you’re seeing and give you a direction to go:

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Hi John,

Thanks for your reply.

I suppose I had both. Some surfaces couldn’t be joined, but some other joined polysurfaces showed enormous leaks.

I think I managed to find the cause of the problem: I redrew most curves in Rhino (in other cases just rebuilt), used them for the top parts as NetworkSrf. I didn’t use the input curves for other surfaces, I duplicated the correspondig edges of the NetworkSrf and worked with them later on.

The difference in the point distribution between the original curve and the edge might have been the primary cause. Now I can join everything into one open polysurface, and the render meshes are also continuous (some really minor gaps occur, when zoomed really in.

If we had the curves built in Rhino from 3 to 5 arcs each, it might’ve given a cleaner result at the first go, but we already had a survey drawn elsewhere.

Lesson learned, I guess…

What tools do you have in mind?

Did you try Custom Mesh for that object? increasing the render mesh resolution should correct those small gaps if the original polysurface is correctly built.

Oh, I forgot to check the render mesh resolution! Thanks for the reminder, you are right - it eliminated a few. The remaining holes are the “real” disjoints that require some more attention.