Weird render issue

Rhino
1

So I am seeing a weired issue when I render a model in rhino.
In this image the first bar is seperate from the rest of the model

carmen 1
carmen 11457×775 89.1 KB

When I boolean union this to the model it says it is a closed solid polysurface, but when I render it there are surface defects to the model
carmen 2
carmen 21457×775 94.2 KB

When I export the model and load it into my printer slicing program the bar looks fine.There is no surfe defect.I dont know why the render image looks wrong.I am guessing it wont matter for printing ?
It is a really large file so not sure if I can attach the actual file.

2

that is only your display mesh it usually does not affect the quality of your nurbs. you can set the mesh to custom to make it denser, that will make the model a bit heavier on the viewport. that often happens after boolean.

you can post a file, try to export it as geometry only and small.

3

thanks.It was driving me a bit bonkers.I thought the mesh was corrupted.I assume if I make the mesh denser the render will be slower.

4

pretty probably :smiley: but that also depends how large in total your render is. it might also be that you do not notice. the problem is getting these little artefacts under control does often imply a rather excessive amount of meddling and overly densifying the mesh. so much that i sometimes explode the geometry and rebuild the parts. i would consider it a bug…

also just be aware if you dont reply to the last post directly, others participating in the topic will only by accident notice your reply. that means if you further wish to engage with the participants of course.

5

no, this will have a very small effect on render time, it might have some effect on initialization time

btw, to me it looks like most of the ‘bars’ have a fillet, while the one that goes mad doesn’t

6

Thanks Gijs,
none of the other bars are attached to the main body yet.I have been trying to fix the issue for 2 days now.I tried rebuilding surfaces and attaching before I filleted because I know from experience filleting can do strange things sometimes and then I uploaded the model into my pritners slicing software and the surface defect wasnt there. So I guess the bug is in the rendering not the mesh generation.I am going to attach the rest of the bars and then do a test pritn of that section of the model.This is a commission build of the mothership from the Batteries not Included movie so it doesnt matter if the rendered image doesnt work.

7

Hi Carl -

If you can post (a simplified version of) the 3dm file, we can take a closer look. So far we don’t know which version of Rhino or which display mode you are using. Seeing some edges being rendered in those images, but other not, might indicate that some of those objects are in need of kink splitting…
-wim

8

thanks Wim,
how would I make a simplified 3dm file? I am using rhino7 and the regular rhino renderer on stock settings.What is kink splitting? I uploaded the mesh into my slicer software and the surface defects seen on the rhino render were not there so the defect doesnt saeem to have made it into the exported mesh?