In the world of 3D rocks, there are a lot of turds out there. I just wanted to share my process of making a modular rock.
I start with a sphere in z brush and then use dyna mesh to pull it around until I have a nice lumpy shape.
Once I am happy with my lumpy shape I use the clipping curve to cut nice hard edges. You can establish a pretty good start with this tool.
After I have cut some hard edges I like to drag some alphas on to the model. This is not for finishing touches at this point. I do this to pull out new shapes and help decide where I want large cracks in the rock.
I then smooth out any noise created by the alphas. I use mostly h polish, the clip curve, dam standard, and clay buildup. I find these tools helpful when dealing with hard edges.
Note: Hard edges are super important!
When creating the rock, I am mindful of where I can hide the seems in cracks.
Once I am finished with the rock I decimate it down to about 1k.
If I needed it to be lower poly then I could retopo manually in topogun to maintain small cracks and edges. This would look cleaner but take a little more time.
The end result is shown in the 3dsmax window. I then use poInt to point seems to trace along the cracks.
Here is the finished seems and the pack.
The first thing I do as far as textures go, is bake out my normals. It is always important to test normals with no textures applied.
Once I know my normals are good I use crazybump to get a nice start for my diffuse. I then overlay textures. It is important to not use too noisy of textures with rocks. I feel like mine could have used some more smooth spots to give the eye a rest.
When I have an okay base I bring my model and textures into mudbox for polypaint. Here I can touch up seems and establish how I want my textures to be broken up.
As far as spec goes I gave it a little bit to catch the eye on the edges as well as the stone texture itself. Too strong of spec could have made it too noisy and look wet.
Note: If this was for a game with major restrictions I would have used two tilable textures for the stone and then masked in between them. The same could be done with the moss depending on shaders.
This is my final product.
I tried a mossy version as well.
I hope this was helpful and turned out okay :)