This is going to show the process I went through to create a simple but effective rock to use in my 3D environment with Max. The only primitive used is a box, and then the rest are down to simple modifiers and editing variables in pre-defined materials to get the desired result.


The first step is to create the box, this is going to be your rock believe it or not. The issue with modelling the rock in this procedural manner is that you don't really notice the difference until you get close to the end of the modelling process (it's only an issue for the first time you are creating the rock.) Worry about getting it exactly how you want it to look when you've finished the modelling processes.

I created my box with 17x17x17 dimensions, and a lot of the numbers in the tutorial I use are used to compliment that size of box. It is a fairly small number, but you can always scale it up afterwards. Feel free to experiment with any numbers used in the post if they do not give you the desired / expected result.


Once you've got your box you need to add some modifiers to it. The first modifier is the 'Spherify' modifier. This will give the model it's general rock shape while preserving the sharp and rough profile of the box. You can leave this modifier out of the stack if you want to create cliff type rocks.


The next modifier is the 'TurboSmooth' which will give your rock a few smoother edges (generally, it smoothes the edges that are too sharp). This is a pretty essential modifier to keeping your rock look realistic, as you will also get issues with the texture without this modifier. Change the 'Iterations' variable of your 'TurboSmooth' modifier to 4/5 depending on the size of your rock and the speed of your computer. Mine is set to 4 as I see no difference when bumping it up any further for it to be worth the extra computing power.


The next modifier involves some of the pre-defined materials that were discussed at the beginning of this post. Add in a 'Displace' modifier to the stack, then under the variables change the 'Map' type to 'Spherical' by clicking on it's radio button. If you don't do this, it will only apply the displacement on a planar axis and so it will not affect your rock in the desired way. Setting it to spherical works cooperatively with the 'Spherify' modifier you added at the start. This process will be true for your model even if you don't add in the 'Spherify' modifier because you want to create cliffs.


You need to tell the modifier what texture it should use to displace the Under the 'Image' heading click the button that reads 'None' under the 'Map' sub-heading. On the list that appears, select (by double clicking your choice) 'Cellular' from it. You need to actually use this map as a material now, so press 'M' on your keyboard to launch the 'Materials Editor' window. Then, on the button that previously said 'None' but should now read 'Map #1 ( Cellular )' click and drag it onto an empty material space in the 'Materials Editor' window.


Still in the 'Materials Editor' window, select the Cellular Material that you just added in and create properties in it similar to what's below, you can adjust things like the 'Size' variable and the different colours to get desired effects for your specific rock. Feel free to play around with the properties, the chances of you breaking max through exploration is very unlikely. Just make sure you save your project.

I have no doubt you'll be coming back to this page when you are refining your rock when the procedural modelling process is over, so remember where it is and what parameters are important and what each one controls. You'll more than likely be focusing on the 'Cell Characteristics' parameters for refining the rock into a shape you desire. There's also a strength parameter on the 'Displace' modifier that you should adjust - for this tutorial just set it between -3 and -4.



The next step is to add another 'Displace' modifier - you can add in any amount of 'Displace' modifiers to your box model that you want, which means more detail but it also means longer render times. For this tutorial you only need one more 'Displace' modifier. Add it in now and we'll take a look at the properties of this one, including another map.


Change the 'Map' type to 'Spherical' like on the previously added 'Displace' modifier, then set the strength to 0.3. Click on 'None' under the 'Map' sub-heading like last time, and this time select (with a double click) 'Noise' from the list that appears. Drag this into an empty material slot just like last time, and on the new material you just created there are some changes you should make here too.


Under the 'Noise Parameters' heading of the material's properties, set the 'Noise Type' to 'Fractal' by clicking it's radio button. Adjust the 'Size' property depending on how frequent and obvious you want the noise in your rock to be visible. Play with the setting and get something you like, or just set it to 1.4 if you want to follow along with this tutorial. This modifier will give your rock some bump map style details.


Now finally, to remove the spherical looking style of the rock and make it look more like it's sitting on the ground, add in a 'Melt' modifier to the stack. You may not need this, and that's up to your own discretion when considering the application of the rock, but if you want it to be sitting on the ground the 'Melt' modifier is going to give it a flat edge at the bottom which you can sit the rock on.



The default values of the 'Melt' modifier should be sufficient to give you the look of a rock, but if not experiment until you've got what you want. You can get some very interested rock formation possibilities when changing the 'Solidity' property.


That's it for the modelling process really. You can adjust the 'Size' property in your 'Cellular' displacement modifier to get different variations of rock shapes and sizes. The only other real thing to do is texture your rock.


In most modelling situations, texturing would be done after a grueling UV process, but luckily for this type of model throwing a texture straight on works quite well. I simply dragged on a rock texture from CGTextures and it looks great.