Hard to tell from the images themselves. But it looks like you have some errant geometry in both pictures.
In the first image, the lower selected vertex does not appear to be connected to both adjacent vertices. This can mean that either what you think is a flat plane is slightly warped, or you have overlapping faces that the render engine is having difficulty with.
In the second image, the left-most selected vertex is misaligned. The adjacent selected vertex also appears to be misaligned. A slight misalignment in the normal direction can be hard to spot and will introduce variations in the visible shading.
In both pictures, the differing colours of the faces indicate different Normal directions.
I am assuming you made this shape by extruding a standard plane rather than using a Text object and converting to mesh. The Text object has an
Extrude property that allows you to set the thickness.
Given the simple nature of your geometry at the moment, my first thought is to scrap that object and start again. If you don't want to use a Text object initially, keep in mind the following tips:
- Extrude along a single axes at a time, or at least exclude the
direction normal to the plane. You can do this when using the
keyboard by using (e.g.)
Shift-Z to prevent extruding in the Z
- Use loop cuts to create new elements of the geometry, this will
preserve the 4-gon nature of your object faces, meaning the loop cuts
and extrusions will behave more consistently.
- Look out for, and remove, duplicated vertices.
- Rotate your view on a regular basis and visually check to see if any
of the faces look strange.
I have tried to fix up an object with some of these errors. It is hard. If you don't want to scrap this and start again, I suggest:
- Making sure your vertices are connected in all relevant directions
- Ensuring your faces are all consistent in terms of n-gon-ness (i.e. 4 vertices)
- Ensuring all your faces are in the same plane without any warping. The easiest way is to ensure that all your vertices are in the same plane. A trick for this is to scale all vertices along the normal of the plane to 0 (e.g.
S-Z-0 through the keyboard on selected vertices)
- Checking for obvious overlaps, and moving vertices (in the plane) to ensure you can see what is happening.
- Removing duplicates