Structure of the rock

Basically, the surface of a rock is defined by working with a cell 1 node, some grunge maps, BNW spots and slope blur them a tiny bit. Using a tiny blurred version of the rocks as a slope blur map will let you create structures that follow the shape of the rocks. I also use the add/sub blending mode for this, after I highpass the result, because it allows me to keep control of the overall shape of the rocks. I am carefully using the slope blur, it tends to destroy the hardness of the rock very easily. Sometimes I take a curvature mask to regain the sharp edges when I feel they got lost with all the FX nodes. I use the previously generated random and bbox mask from the flood fill tools to add variation. Making some effects stronger or just completely different. All these are packed into reusable instances. I also do a lot of experimenting, try out some different noises, slope blur them, warp them, direction warp them and just see what happens. Most of the times, SD for me is like jamming on my synthesizer and just listen when I come up with some cool tune that has some potential.

Scalability and a feel of ‘organic changing’ like in real nature is important to me. I try to mix noise maps always based upon overall shape of the terrain and / or the size of the rocks. (the flood fills tools are handy for this) As previously mentioned, I keep track of mainly three maps: the height itself, a random mask and a bounding box based mask.

So, to sum up: the first pass is a texture that renders the rocks and will look very stylized. The second part if where I add all FX and the last part is where I add colors, roughness and so on.



What way can you make the material feel organic and blend so well? What is the nature of the way SD helps us blend these materials so well and organically?

Having an organic feel to a nature type of texture is very important to me. Scalability is key here I think. Create a lot of variation of sizes and position. Create clusters and let the clusters spread out. Add different type of noises to everything. For example, combine more noises with the slope blur already can give a more non uniform look. And then break the rules. For example: have sharp rocks and then introduce some flat stones. Or have a lot of greyish rocks and suddenly add some pure white pieces. Break the uniformness. And if it was me, I would love to have every single parameter in SD map driven. ?

Generally, I love a node based solution. SD has one, WM has one, UE4 has one. Speaking of SD, I also think being able to directly see the texture in 3d world makes another difference, too. Otherwise it just would be sailing without a compass. SD comes with a lot of premade nodes to streamline the workflow to create PBR materials much more easily. For example, generate a normalmap, have some PBR ready nodes, ability to create instances and going advanced with the pixel processor and FX nodes. For the blending inside one material with different type of nature elements such as sand, dust, rocks, I use the heightblending node and the lighten / darken mode a lot.

Colors

That indeed can be a tricky job. First, reference is key here. I think it is important to see the overall picture and analyze what exactly is erosion, wind, water, rain, gravity, dust, snow and sand doing. Technically, as previously mentioned, I keep track of the random masks to add variation. If I am using the floodfills, it is easy to obtain a random mask, because SD comes with a default floodfill random mask. If I am on a tilesampler workflow with scattered rocks, I duplicate the tilesampler and set the color randomness to 100%. Then the input patters must be masks of the rocks. Then, for the diffuse / roughness, I mainly use three key components: curvature node to highlight edges, an AO / normal node to add dust or dirt, distortion warp with grunge maps with extreme values. I try to keep colors bounded to the shape and then break the rules. Next thing is just experimenting what works. Trying out different colors and play with the blending mode will results in some surprising effects. Also, not being afraid of colors is helping me a lot. I try to dare to use abstract colors sometimes such as pink or green and then blend those and just see what comes out of it. The ground textures are always some mixes between noises and I add the rocks on top of it. Most of the times the overall look and feel will benefit from it. Even a very plane gravel field can benefit from having a cell noisy based floor. A good tip is to look at flat surfaces in real life while the sun is at a very low altitude. The shadows become long and will reveal much more how flat an area (not) really is. You can start seeing patterns. Ground textures are also a combination of noises. I also use a lot of the non uniform blur node which is very great to create mud, sand and so. Or use the previously generated stone field and let it shrink in to the ground and start adding new layers on top of it.