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With our environment set up, we're ready to start doing test renderings. We'll want to adjust the exposure control. Go into Rendering > Exposure Control. And what we see in here are just the same values that were left over from the chapter on studio lighting. We've got an exposure value of nine and we've got the image control set to pretty neutral values, mid-tones of 0.5 and just a little bit of burn on the highlights of 0.02. So with those values leftover from the previous project, let's take a look at what it looks like if we render it.
Okay, here's our first attempt. And what you'll notice here is that although the object is looking a bit dark, the background is extremely bright. And we actually can't remove that background. It's always going to render. We can replace it in Post by using the alpha channel. If we go up here, we can click on Display Alpha Channel. What you'll see is the black areas have transparent alpha. And that means in Post, in an editing program like Photoshop or AfterEffects, we could replace that background with something else.
However, the actual RGB pixels will always render that background image. And in fact, we can't turn that off, so that actually might be a problem if you've got a really high contrast between the object and the background, and then you need to replace that background with some other colored background, because these pixels here are going to be anti-aliased. If I zoom in here with the wheel, you can see that these pixels are blending here along this edge, and there's really nothing that we can do about this.
The issue could be that when you composite this in Post, you could get some halo or fringe around your object. So, that's just something to look out for, and again, there's not really a work around for this using the environment method that we're using here. But, later in this chapter, we will look at a definite work around, which involves using a piece of geometry, instead of the environment, from the Environment and Effects dialog. So now, we want to work on the actual brightness values of this, and make this better. As you know, you can normally adjust the exposure value here.
If we bring this down to a lower value, it should make our image brighter. Like, if I bring it down to something like five or whatever, and do another render, under normal conditions that's going to change the brightness. But as you can see here, nothing has changed. We're getting the exact same brightness that we did before. And that's just because we need to choose a different option for the scaling of the exposure control. I'm actually going to cancel this because I can already tell this is not going to help me. If we scroll down a little bit here you will see Physical Scale and what we need to do here is choose Unitless.
And then we can adjust this value to something else if we want. And this exists so that we can scale the image-based lighting into whatever range we need to. The physical unit setting is designed to be used with photometric lights. But here with Unitless we can set this to whatever arbitrary value we want. All right, so let's set this back up to nine, and try this out with Unitless with the default value of 1500, and click Render.
And you'll see that it's still doesn't look any different. And there's one other switch we have to turn on here. I'm going to cancel out of this. We have to go up to the top and there's a very important switch here that says Process background and environment maps. And if that's off then nothing that we do here is going to matter. We need to turn it on and that's going to change the lighting and you can see it actually in the view ports as well. With it off we get a bright background, and with it on it gets dimmed down. And this is going to give us a pretty good idea of the brightness of our rendering as well.
With that dimmed down then that tells me I need to increase this unitless amount here. And, of course, I've already played with this and I know what value I need in this case. I'm going to set this to a value of 40,000, which seems really high, but it's going to give us a nice, crisp render. Go ahead and click Render on that. Okay, so with those options adjusted, now we're getting a nice, bright render. There's one last thing I'd like to show you regarding exposure. We can actually control the brightness of this scene by going back into the bitmap setup and changing the histogram and the black and white point.
Let's do that. We'll go back in the Material editor, and back into the bit map parameters. You might need to double click on that bit map node and you'll see the path to the file. Click on that button and we're taken back into the Select Bit Map Image file dialog, but we don't want to actually select a different file, we want to go back into the set up. Notice that the button looks grayed out, but this is just a minor bug in 3ds Max. Click the Setup button once, and it will light up. Click it a second time, and we can go back into the HDRI load settings, or the settings for whatever type of image you're dealing with.
Remember previously we chose Default Exposure. If we want the adjust the black and white point, we'll turn Default Exposure off. And then I'll bring the white point down a little bit to a value of about one, and that's brightening this thing up. Anything above this red line, to the right of that red line's going to get cropped off. Same with a black point. I can enable it and then change its value, bring that upward a little bit to a value of about, let's say, negative four or so. Then you can see in the preview here that we're getting a much darker rendering.
Basically anything below this line to the left of that red line is getting cropped off. So all of these dark pixels are just being crushed down to black. All right, so let's make this a really clear example by setting that to about negative four or so, and click OK. And then click Open as if we had chosen a different file, but of course we've got the same file chosen here. All right. And we'll do a comparison. Take the previous image and clone that off to its own window and then render. And as you can see it's considerably more contrasting.
We didn't change the exposure, we didn't change the units setting, all we did was adjust how that bitmap file is being interpreted. And now we've got much darker reflections down here. Remember, we've crushed all the blacks. Now I wouldn't actually use this particular setting in production, but I made it really extreme so that we could see it here on the screen. So it would be a really good demonstration, what it would look like. But in fact, for the purposes of a production render, I'm actually going to go back into that dialog, and set it back to Default > Exposure settings.
Go ahead and clone that off, just to compare it. And go back into the Material editor once again. Back into that bitmap setting. Set it back to Default Exposure because what we had looked good. Okay, cool. So we're looking pretty good. We're back to this state now. And we want to adjust some of these materials and clean this up a bit.
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