question about smoothing groups and normals
Hey guys,
I have generall question about smoothing groups and normals, from my understanding if i put the same smoothing group on a UV island which is stiched together from 5 different polygons, the result should be "normal issue free" seamless...
When stiching the same 5 polygons together to 1 UV Island and i'm using different smoothing groups i become instantly "normal issues" seams, right? When uisng different smoothing groups and every polygon is on his one and not stiched together, i'm also "normal issue" seams free.. right ?
My problem is the following, i have a mesh which is seperated in different uv islands some islands have multiuple stiched polygons "same smoothing group for the polygons" and some islands are single polygons.... Some UV island which are including a few stiched polygons are showing "normal isue" seams in the areas where they are stuched together... but why? they all are using the same smoothing group to show this part seam "normal issue" free ????
Any ideas ?
I have generall question about smoothing groups and normals, from my understanding if i put the same smoothing group on a UV island which is stiched together from 5 different polygons, the result should be "normal issue free" seamless...
When stiching the same 5 polygons together to 1 UV Island and i'm using different smoothing groups i become instantly "normal issues" seams, right? When uisng different smoothing groups and every polygon is on his one and not stiched together, i'm also "normal issue" seams free.. right ?
My problem is the following, i have a mesh which is seperated in different uv islands some islands have multiuple stiched polygons "same smoothing group for the polygons" and some islands are single polygons.... Some UV island which are including a few stiched polygons are showing "normal isue" seams in the areas where they are stuched together... but why? they all are using the same smoothing group to show this part seam "normal issue" free ????
Any ideas ?
Replies
1. If you have a hard shaded edge (i.e. smoothing group seam) you MUST have a split in your UVs (and generally a bit of a gap to account for padding).
2. If you have a split in your UVs, you DO NOT need a split in your smoothing. However, it generally won't actually hurt anything to add one (in fact, it can often help).
3. If you have any hard shaded edges, you MUST bake with a projection cage to ensure you're not going to get seams. It is generally a good idea to always bake with a projection cage.
I use the 'Smoothing Groups from UVW Shells' function of the textools. So i alaways get good results.
So my question is why i'm getting seams in the stitched areas when using the same Smoothing group for all this parts?
If you have a cube on a single smoothing group like above, you're essentially telling it to try bending light across the surface as if it were a sphere, which doesn't make sense. The correct configuration for a cube would be to have 6 separate UV islands (with space between them all, or you'll get bake errors) each on their own smoothing group.
The closer two polygons meet at a right angle, the more you should consider splitting the smoothing group and UVs there. I tend to start splitting things more extreme than 45 degree curvatures (as seen on chamfered edges).
Use this rule of thumb on top of what Farfarer already said and you should eliminate most if not all of your baking problems.
Normal maps are a cool thing but where is the sense of using them when my textures or my mesh has a ton of texture seams ?
As for general texturing, if you are placing your seams intelligently then most of them are not a problem. Try placing seams at corners, breaks between materials, and in places that are concealed from a common viewing angle; and of course follow the guidelines above for when to split your UVs.
Using software that allows you to paint directly on your model and over seams (ZBrush, 3DCoat, Substance Painter, etc.) will help reduce the obviousness of seams compared to manually aligning things in Photoshop.