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In this video I'll look at baking an occlusion as a foundation for rust. I have got a Toolbox here, and I'd like to put a rusty texture on. But what I want to have is besides just any old rust painted on, occlusion is a basis for rust that has built up because it's been sitting outside on the ground and gotten generally splashed. What I'll do, then, is put a ground plane underneath it and render the occlusion on part of the surfaces. If we look here in the UV Texture Editor, you can see I have unwrapped it.
I have taken half of the UVs and aligned them where I want. Here is the top and one side and one end. Being that this object is symmetric, my plan is to bake the occlusion and really the part I care about are these three shells. I have stacked these three over here essentially out of the way, and I don't care if they clip. What I am going to do then is bake the occlusion and then take the remaining three shells and stack them over, so I have the same occlusion on both ends, both sides, the top and the bottom. If I had done these before, stacking them and then baking.
I'd end up with black from the bottom occluding into the top and black from the sides onto each other and the same at the ends. So sometimes what we'll see just like with a shutter is baking on a part of an object and then later using the UVs and a stack on a lower res. In this case this is the low-res, but I'm baking onto a ground plane, and so I want to make sure that my UVs are spread out, so I don't get too much darkness. I'll go back to Object mode, hold Shift and right-click, and put a Poly Plane under my Toolbox.
I'll make sure it's snapped cleanly under, pressing V and snapping it down to the bottom. Now I am going to bake this, picking the Toolbox and pressing F6 to go to the Rendering Module. I'll go under Lighting and Shading, and there's my Batch Bake (mental ray) again. I'll rename the prefix, in this case calling it Toolbox. I'm going to try a little higher falloff, maybe 6. I'll leave my rays at 128 and all my other settings the same, baking shadows, using an override, 1024 square, and one map and alpha.
What this is going to do, then, is factor this plane into the occlusion, and I'll make sure up at the top here my Bake optimization is for Multiple objects. I'll hit Convert and Close and see what the occlusion looks like. My inclusion bake finished. I'll close this Baking Options dialog and take a look at the material. I'll scroll over. I have got a lot of attributes going on in here, and that's okay because I'm going to discard that history later. I'll click on the Incandescence texture slot, and there is my occlusion. I'll click View and see what it looks like. Here in my viewer, it's working perfectly.
What we're seeing is that I have got even occlusion splashing up along the sides and the end. The top is bare as I'd intended, and over on the right side here is a mess. What we are seeing then is that these UVs are overlapping. I would have seen this kind of occurrence all through if I had stacked the UVs in advance. So planning an occlusion on half the object helped. I'll go over to Photoshop, open up this document and a rusty texture I have painted as well, and start to putting them together for my Toolbox. Here in Photoshop I have got the good side of my unwrap and the side that was, well, not too pretty.
I am going to take this out just because it's visually a little distracting. I'll select it with my marquee and hit Delete, and I have got my Contents under Use set to Black, so when I delete it's just gone. I'll deselect by pressing Ctrl+D, and then I have pulled up 08_04_rusty. Now this may look like a strange swirly fractal pattern, but it will work for rust. What I have done then is the same procedure I did on the pry bar and the hammer, using clouds and the Magic Wand to generate some clouds and then delete part of them to get a speckly, loopy rust pattern.
I am going to take just the rust and copy and paste it into the other document. I'll put in a new color layer there. I used the color in here just to see how the rust would look. I'll press Ctrl+A to select all, Ctrl+C to copy and back over to the Toolbox.tif I'll paste it in. Obviously, this rust is too big. So I need to downsize it by pressing Ctrl+T to Transform and holding Shift and constraining those proportions. I'll pull it back down to half the Toolbox and hit Enter.
It's a speckly dirty pattern, and I am going to take this and clone it, holding Alt to copy and cloning this image. If there's any seams I am going to come back and camouflage them, painting things out of adding some more rust. I'll use this just as a stamp almost or tiles, tiling along and getting the general speckly rust in place. Then I'll press Ctrl+E to mash down these clones into one image. Then I'll double-click on the background, and I'll call this rust.
I'll take my layer 1 and slip it underneath and pick my rust layer and make it a Multiply. Now I'll slide a color layer under, pressing Ctrl+Shift+N and calling this color. I'll press Ctrl+Left bracket to slide this down, and I'll put a color in. Here in my paint bucket is my blue I used on my Toolbox. I'll make the layer 1 a Multiply layer as well, and it starts to become speckly rust. I'll take the rust overlay and colorize it, pressing Ctrl+U, checking Colorize and saturating.
I'll bring up that Saturation and swing the Hue over to red. There is a red rust as if it's been sitting outside. Now I need another layer. The occlusion becomes the foundation for this rust. I'll press Ctrl+Shift+N and call this one rust2. I'll eyedropper my rust so I am in the same values, possibly going in and increasing the Saturation and bringing up the red a bit. I am going to use some of the same painting techniques I did on the gas pump. What I'll do to keep it constrained is press W for Wand, and I'll Magic Wand out of the rust layer the black.
Then I'll use my Marquee, press Alt and deselect the top section. Because they are so close I have got to watch out for continuity and painting. I'll press B for brush and use one of my scratchy brushes I have already set to. I'll make sure that I'm brushing it a fairly large size, in this case about 250, and that I'm brushing in here as a Multiply. I'll bring up the Opacity a little bit and scratch away on his Toolbox.
I'll start to add in this rust. It looks like I needed to invert that selection, it's okay to find that out. Sometimes we just make goofs, and we miss them, and we have to go back and redo a little bit. I'll press Ctrl+Shift+I to invert that selection, and now I am going to paint only inside the Toolbox. The occlusion provides a nice foundation for rust, and I'll make it creep up the sides. I am also going to darken this color a little bit after I have seen it. Here is the other nice thing, because I'm working on a layer if I decide, gee, that rust isn't really it.
I'll delete it, and I'll come back in and brush again. I am going to add in some scratchy rust, blending it in with the occlusion. Using the occlusion down here as a basis for where it rusts. It's particularly useful on more complex objects, objects that need different interaction with either themselves or the ground. Where occlusion helps pop out detail in rust, this is a fairly simple one so the occlusion provides a nice base, there's a big scratchy area on the middle of this. I'll add some rust along the corners, brushing it in, reducing the Brush Size and painting it along.
I'll make sure it matches all the way across and paint down the sides. I'll go on the top here as well and the ends and paint in that rust, the occlusion is a terrific starter and using that falloff distance I can make that occlusion really creep up the sides. I am going to rust this Toolbox pretty thoroughly, painting in that rust on all the corners so it's a good match. I'll go all the way around, letting that rust really build up over time, making sure that it really has some age in it. There is my rusty Toolbox.
I'll press Ctrl+D to deselect, and I'll save this image out. Because it's a working file, I need to save the PSD. I'll press Ctrl+S for Save, and it wants to save a TIFF because TIFFs carry layers. What I prefer to do is do a Save As and save this out as a working PSD. That way when I go looking for textures. I'm just choosing the flattened TIFFs. I'll put this into my sourceimages folder, and I'll call this one 08_04_end.
Now I'll save out the TIFF, pressing Ctrl+Shift+S, and calling this 08_04_end.tif, turning off Layers and turning off Alpha. It's going in sourceimages, and I'll go back into Maya and see how it looks. Here in Maya I'll get a new material on, putting on a Blinn. Into that Blinn in the Color goes that file I just made. With my objects deselected and the wireframe off, it's a speckled, dirty, rusty Toolbox.
I can do a little more in the painting, and a normal map would probably help. But it's definitely a metal speckled box in here and looks pretty good. It's ready for a specular map where the Toolbox was shiny, but now the rust has dulled it down. Occlusion is a great way to detail and drama in textures and also provides a thorough foundation for rust and dirt. Depending on where we cast the occlusion, we can get the occlusion to reach up an object, or we can have it as simply a basis for things that have been, say, sitting on the ground and getting rusty like his Toolbox.
In the next video I'll add in some specularity into this Toolbox to really finish it out.
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