Ugly shadows on flat surfaces

I am trying to model out a fountain (to use with liquid physics), but I have this really ugly shadows running across my fountain. I tried flipping normals, and recalculating normals (like all the solutions I found), but that solved nothing at all. I used cylinders in a perfect circle with knife project , followed by bool intersect to create the holes. I have never run into this before, and this is badly effecting subdivision surface, as it creates ugly planes where they should not be going.



nGons are causing your problem. nGons and subsurf don’t get along. You have to remember that when it comes to rendering, the computer turns all quads and ngons into triangles and then creates your image. That’s why you get triangular shading problems.

Go back and clean up your mesh.

this is due to sloppy mesh, as was stated above. don’t use booleans and expect to get clean mesh right off the bat. You will need to make all of your surfaces have only 4 connecting points, otherwise known as quads. This will fix your issue.

Is there some sort of technique I should be using to clean this up? Manually adding triangles (since triangulate doesn’t work so well) seams to be not very efficient.

I tried deleting the faces, and using beauty fill, but that created creases just like normal triangulate. I think my circles aren’t exactly flat with itself, but I was not able to figure out how to flatten it using normal, local or global scale of Z to 0.

I am going through and just removing all the holes. I am thinking it is too much to just fix, than later go back in a do with the “right” technique for adding in the holes I wanted.(Which I am unsure the right technique for adding the holes, since most of what I read is either debates or bool for adding holes. Knife project did not work at all either).

8 ways to make a hole:

worth your 10 minutes :slight_smile:

Grim don’t get discouraged,
Booleans are not bad, but they are not smart, so you have to be smart when applying them and cleaning up after them.

all the guys above are correct, I would just like to add:

Think of it like this all: edit mode modelling is triangles (take a plane and move 1 vert out of the plane=2 triangles)
quads(sub-d modelling) restricts your edge select choices (protecting you from yourself) it’s a trick. (take a plane subdivide it once, select 3 verts on a diagonal line and move them out of the plane, the invisible edges become visible as they become the transition from one plane to another)

To ensure good topology you want to dictate where the mesh changes direction and which edges remain hidden( hidden being when the 2 adjoining triangle faces are on the same plane)

With your above model you could get the same result with or without booleans, both methods you will have to pay attention to which edges you want to be transition edges, you can do this in several ways, edge loops (basically 2 lines of verts always in parallel on one axis) “Mean Crease” and edge split, you can also us mesh “clean up” by making planar faces, and altering normal direction.

Maybe this will help. Please excuse the typos. :slight_smile:


Lots of good info in here but I would like to add my two cents. While quads are great for edge loops and tend to give you good results for shading, they are not always required. Over my time of modeling I’ve learned that you only need a quad when you have a curved surface that the render needs to calculate the light along those planes. Basically you need to always go with the curve when using quads as you can see in this image.

If you go against the curve you will get ugly results.

Also something a lot of people miss is “skinny tri’s” really thin triangles whether in a quad form or not are bad. Due to how vertex shading works (shading from one vert to another) skinny tris produce odd results. These images show how it works very well.
The only way to fix skinny tris is to fatten them up.

Another great way to stop tri’s from creating nasty results is edge split or mark sharp around the planar surface that the tri is on.