Skill Level Intermediate
- [Instructor] The 3ds Max gradient ramp map gives us the ability to arbitrarily remap the colors of another map. In other words, we can feed a texture into the gradient ramp and change that texture's color palette. That is super useful in cases such as this terrain. Let's take a look. I'll render this using ActiveShade on frame zero because starting on frame one, we've got some clouds that will slow down the rendering. When that renders, we can see that we've got a nice color here on the rocks representing mineral-rich desert rocks. What I've done here is I've taken a grayscale noise and piped it through a gradient ramp map to change the color palette. That does work fine. However, the gradient ramp map has some limitations. With the introduction of the Arnold ramp RGB map, we now have much better control over the remapping of one color palette onto another. Let's take a look; I'll open up the material editor. Here's the shading network currently. I'm using the gradient ramp maps, actually two of them feeding into a mix RGBA Arnold node. I'm using a curvature node as a mask so that we can achieve the effect of having some areas of brighter color. I covered that process in another movie earlier in this weekly series. Let's make some changes here. I'm going to delete these gradient ramp nodes. Just drag a rectangle around those two and press Delete. Now let's create the Arnold ramp RGB node. Right-click in the graph and choose Maps, Arnold, Texture, Ramp Rgb. Just for now, let's connect it to the base color of the Arnold standard surface material. We can see here in our ActiveShade rendering, we're getting a mapping of black to white in one dimension, which just happens to be the U axis. Now let's double-click on that ramp RBG node to load its parameters and we'll call it terrain color. The first thing we want to do is change the type. It's set to U. We can change it to V and it will map in the opposite direction, but what we really want is custom. Switch that over to custom. Then here in the shading network, I have an output node that's just simply amplifying the noise. Let's take the output of that output node and plug it to the input of the ramp RGB node. Now we should see some coloration here that corresponds to the actual noise pattern. Now we're ready to change up the colors in the ramp proper here. Here's where the ramp RGB node shows its true versatility. We're able to actually make this ramp large and take up a greater area on the screen, which gives us far more artistic control than we had with the old gradient ramp node. There's a button here, little up-facing arrow. Click on that and you'll launch a child window. It's the same as this graph here; it just gives us the ability to resize that graph and make it however large we want so that we can put however many points we want on this graph. We have a point number zero at the beginning and a point number one here at the end here. We can select one of those by clicking on it, and then we can adjust its color by clicking on this value field here. That launches the color selector and then we can just make some changes to the color, maybe increase the saturation value and give it a red rocks kind of look. We can go over to the other point here at the end of the graph; select that. With that color selector still open, make some changes there, too. To add points on the graph, we can just simply click anywhere on one of these RGB lines and that creates a new point on the graph. We can move that around. We can make adjustments to the colors directly here by increasing or decreasing the red, green, and blue components. I'll create another point over here. We can copy and paste colors very easily. Just go over to one of these other points and select it, and then right-click on the value and choose Copy. Go over to another point, right-click, and paste, and then make whatever adjustments we want. After making some further adjustments, I have more or less the result that I want. I think I actually have too many points here, so I can delete some points if I want. I can select one and just press the Delete key on the keyboard. Or if I wanted to, I could change the interpolation between points. That's done by right-clicking on one of these points and choosing a different interpolation type. The default is Catmull Rom. If I chose Constant, then I would have hard-edge transitions. Let's do a couple of those. Just for illustration's sake, I'll right-click and choose Constant on a few of these. We can see we're getting a stair-stepping effect here. That leads to hard-edge transitions here in the ramp. I'm going to actually switch those all back to Catmull Rom, which is a smooth-splined interpolation. That looks pretty good. All we need to do now to get the effect we had previously is reinstate the curvature as a mask between two different versions of the ramp. I'll close this child window and create a new map node. Click on the output of the ramp RGB and drag out. From the pop-up menu, choose Maps, Arnold, Color, Color Correct. Then in the further pop-up window, choose input. Now I'm connecting the ramp RGB to a color correction node as well. Then double-click on that color correct node. I'm just going to make a couple quick changes. I'm going to change the gamma here to a value of three and the saturation to a value of two, which is going to give us a brighter result. We can see that if we temporarily connect that color correct node to the base color of the material. Now we've basically given it a brighter look. But what I really want here is to have a bright and a dark version of the ramp masked off by the curvature here. Let's re-connect this mix RGBA node, take its output, and plug it into the base color of the material. Then our color correct node will go into input2. Finally, the direct output of the ramp RGB node will go into input1. What we have here now is a mask based upon the curvature of the surface. Wherever the surface is highly curved, we'll see input2, which is the lighter version that's been color corrected. That's a basic introduction to the ramp RGB node in Arnold. The only thing that you can't do with this node is supply maps to each one of the colors like you can with the gradient ramp, but that's a small price to pay for the ability to make that window larger and be able to fully control the output of that ramp.