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In this video I will give a brief overview of a normal map showing what it does to the wood table, when I had some relief to the surface. Right now in the scene, these are flat. What this means is that although it's got a color in it which looks like wood, this Blinn material is exactly flat and uniformly shiny. If I take my light and move it over in the scene, turning on the high-quality display and pressing 7 to show lights. When I pull this up, we can see that well it's a flat surface, and as I pull that light back and forth, we can just see the cracks in the table.
What we will see in most game objects is that we have a diffuse map and a normal, so the surface looks like it has some variation Because we are dealing in low poly objects, we need to make sure they look as well real and textured as possible. I will go over to Photoshop and make a couple of different maps to illustrate this. Here in Photoshop. I've got the Wood texture I had created previously. What I am going to do is to turn off the dirt and turn off the color, leaving me with just my grain. I am going to first export this out as a bump and show what just a straight dump map looks like in light.
Then I will make a normal map and look at the difference between. I will save this out as a flattened tiff, picking tiff, turning off layers, and calling this 06_02_B_end. I'll put it in the source images that way I can find it quickly in Maya. Now I am going to make a normal map. In a Bump map, white is high and black is low, and it's not a specific unit, it just means that the surface looks like it pops out more, it's got some relief, but bump maps are one direction, up and down, which means they may look a little jagged and what should be the side of a surface. Now I will make a normal map.
What I will do is to clone this layer, and I'm going to use xNormal here. I'll switch this layer back over to a normal as you can see when I cloned it, because there was a color burn, they burned in, and it got a little odd looking. I will choose Filter > xNormal > Height2Normals, we've also got the NVIDIA normal map tools and really the difference in those is the softness of the normal. We may want a slightly harder or softer normal or a different scale. If it gives you the right look whichever filter you use is just fine.
I will use Height2Normals out of xNormal, and it will pull up the xNormal dialog. In the xNormal preview, I can just see a little bit of variation across there. What we are dealing with here in a normal is first how smooth is it. Normal maps tend to look better with a little bit of smoothing on them, although if we want it to be a little more jagged, we can reduce this number. Our method of sampling here determines the quality and how is it sampled. A little bit higher like a 5x5 may take a little more time, but be a little bit finer.
I am going to leave mine at the default 4SAMPLES, as this is pretty good all over. If we need we can swizzle the colors. Swizzling will do things like flipping red and green. Red and green in the Normal map give you surface direction, making the surface look like not only is it going in and out, but reorienting to angle and reflect the light appropriately. I will leave this at the default and hit Continue. What I get is a largely blue rainbow colored map, we will call it. I will zoom in and take a quick look, and we can see the wood grain, and there is our red and green colors showing up.
In a normal then blue is strength and red and green are direction. I'll save this one out as well as a tiff and bring them into Maya to compare and contrast, I will turn off Layers and call this 06_02_N_end, so I can see both of them. Here in Maya, I am going to make a different material for the normal and the bump. I'll put it on planks adjacent on this table, so we can really see the difference in the light. I'll pick the first two planks and assign a new material to them using a Blinn.
I will pick Blinn, and I will put in the color I have already got. I will click on the Color texture and in this Blinn, I'll put a file in. In the File node I will put in the latest color texture 06_02_start, and there's that wood grain I had made. Right now, my planks look, well, just like they were. I will go up to the Material, and I'll name this Blinn, notice that above the Blinn is that shading group, and there's the Blinn material in it. If we need additional properties, such as Counter Rendering in mental ray we can go into the Shading group.
But just so you know what you're seeing if you go up one node too far, it's just the shading group that governs that material. I'll name this one Color, meaning it's just the straight color material. Now I will put another new Blinn on the middle two planks assigning a new material and choosing Blinn. I'll put my color in the same image choosing by file 06_02_start color. I will go up one level and call this one bump. This will get the grayscale bump image. I'll scroll down to the bump mapping and click on the texture, adding in a file and going into the File node.
In that File node, I will put in the 06_02_B the grayscale bump. Here in the bump2d node it's regarded as a bump and then use as dropdown. We can already see a difference here and the wood grain is pretty strong. I will name this material Bump. I will pick the last two boards and assign one more material to them, again, assigning a Blinn not changing any of the properties and putting in the color, in goes that same color file. And now I an going to put the normal map in.
I'll go up to the root material, scroll down to the bump mapping and click on the texture. Into the File node, I will put in my normal map. There is the normal, and once I put it in, I need to make sure under Use As, I tag it as Tangent Space Normals, there's a subtlety to it. What we can see in here is that the wood grain has pretty severe relief of the bump. I didn't change the strength of the bump at all and so the normal map may have been a bit muted. However, more importantly, the bump map tends to be very jagged looking, the normal map has a subtlety to it as the wood waves up and down, the surface is reorienting in the light.
I'll move my light back and forth, selecting that point and pulling it forward. As I pull it over, you can really see that surface change. To illustrate this just a little bit further I'll pick one of the board with a normal map material on it, which I need to name normal as well. I'll go into that bump map section and go up to the output connection which is the bump2d node. I will push up this depth, we may need in our normals to bring this depth up a little bit, assuming they'll run at a strength of one once we get them in game. And so when Photoshop is part of the export, we may need to increase that scale.
With it selected, and bringing my light back and forth, we can see a surface variation. When I bring the light down to the surface and pull it over, we can really see that in action. As I pull this, we can definitely see that the wood has a really pleasing variation, it's not nearly as granular or gritty as the bump section. But definitely is different from the straight color. Here's a last test. Instead of a point line, I'll use a spot. I will make it a spotlight by using the dropdown, press E for rotate, and swing that light down to focus on the table.
I will pull down my notes and change the Cone, Penumbra, and Dropoff. I will these at 75, 5, and 5. Making the light bigger and softening it out. I will grab this light, pull it up, and angle it a bit. This is much more typical of what we would see in a game. Where we will see this kind of light angled over and softly on a surface. As I pull this around, we can really see a difference in the normal map, it's got a subtlety to it and a small bit of wave versus the bump is, again, very gritty looking.
I will pull the drop-off down on the light just a little bit, and cast it in even further relief. I will switch over to viewport2.0, and this really displays things as accurately as possible in the way they will be seen in game. As I rotate my light over, we can really see that the normal map has a nice feel to it, without being excessively, well, big like the bump, but it's still got a difference in it unlike the way that color looks. As I spin around, you can really see this clearly.
The normal map has a smoothness to it, as if the wood has been worn away over time. Normal maps then are a great way to add realism to a game, we tend to be much more forgiving of hard edges, if we see softness in the middle of the surface. They also allow the light to really change as we spin around. As I look more at the light we can really tell a difference the bump and the normal. Normal maps give us strength plus direction. Bump maps only give us strength and tend to look jagged. We may see normal maps used in conjunction with bumps where the bump map takes care of small details and the normal map takes care of the overall, we will call it contour, but it's really the overall rise and fall of the surface.
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