Join Paul F. Aubin for an in-depth discussion in this video Adjusting the exposure controls, part of Revit: Rendering.
In this movie, we're going to look at the final section of our rendering dialogue, the image area that includes exposure control and options to save and export our images. So I'm in an interior scene this time, and we've got a camera view looking out through some big glass windows here, and let's go ahead and generate rendering. So for the quality setting, I'll choose medium, and I'm going to choose printer resolution, just because it gives me a little bit more control. At 150 DPI, that will give me 750 pixels across, which is what I want to work with for this experiment, and I do need to change the lighting scheme, since we're on an interior rendering here, so I do have the artificial lights in the scene, so I'm going to choose sun and artificial.
However, I don't expect the artificial lights to really have a huge impact on the rendering, so probably interior sun would give you almost the same effect, but that's fine. I'll just go ahead with sun and artificial. I'm going to accept the rest of the defaults here and click render. Okay, so as you can see, we've completed the rendering and it's awfully bright, so let's talk about what we can start to do here now to make adjustments. One of the really interesting things about the mental ray rendering engine that's included with Revit is that it actually stores the lighting information in the pixels of the image.
What this means is that after you've generated the rendering, you can still adjust it. So if we come down here, we've got this exposure control button here, and I'm going to click that, and that displays the exposure control dialogue. Now, at first it can be a little bit baffling to work with some of these numbers here because the ranges are all a little bit different. For example, the exposure value ranges from negative six on the bright side to positive sixteen on the dark side, so I'm not exactly sure where that range comes from.
Let me click reset to default here, just to get it back where it started from, which was nine. If you click the little help link here, that will display your web browser and you can actually read about each of these controls and not only that but you can see the ranges, so the negative six to 16, and then you can see the highlights, for example, goes from zero to one with point two five being the default, and each one of those has their ranges in there, so that might be helpful to see, but what you can do is just drag these interactively. Now, I doubt we would want the exposure any brighter, so what happens if I drag this just a little bit, and it doesn't take very much, and then click apply.
You can see that just dragging to about ten has a dramatic impact on the rendering here. Okay, so likewise with these three here. If you're familiar with Photoshop and you've ever worked with a histogram before, and you're familiar with the concept of highlights, midtones, and shadows, so basically if you took all the pixels in the image and graph them on a chart, you'd have all your darkest pixels on one side of that chart, all your lightest pixels on the other side, and then in the middle you'd have a big range called the midtones, so by adjusting this first slider, it only affects the lightest pixels, and this one only affects the darkest pixels, and here, it will affect everything in the middle.
So I doubt that we really want to do anything to brighten up the highlights, but you know, if you wanted to, you could actually darken them slightly, and you could sort of see that make a change. You know, it only takes a little bit for each adjustment to be seen, and then the midtones here, that brightens it up a little bit, or if I go this way, that starts to darken it a little bit, and over here, for the shadows, same thing. If you wanted to darken your shadows, or if you want to start to lighten them up a little bit.
Okay, so you have a lot of control, and just by adjusting these sliders and kind of seeing the results that you get. Now, the white point is actually a really useful setting because it controls the overall tone of the entire image. You can see here, it says cooler and warmer. So, if we went to the extremes here, if we went way down in the cool side, the image is going to become very blue, like it's something out of ice age, and then if we go all the way to the warm side, and we click apply, then it's going to become very orange and yellow and very intense, so if you do something that's a little bit less extreme, and I'm going to set this to maybe in the mid 5,000 range, around 5,900, and click apply, then that feels a little bit more natural to me.
It's a little cooler than what it started off at. It started at 62, but it just cools it off just a little bit. Now, you can actually type in here, as well, so I'm going to actually type in 5,900 exactly. Now, the saturation is another fun setting as well because if you go all the way to the left here, you're essentially making it into a black and white grayscale image, and if you go all the way to the right, then it becomes very intense, almost like an illustration, so you can certainly fiddle around with the saturation level that you want here, so I'm mostly going to leave it where it was, at the default saturation level.
So, when you're satisfied with the changes you've made, you can click ok, and now you can actually save this image, and you can do that in one of two ways. The first option is to actually save it to the project. Now, notice here there's a renderings branch on my project browser, and there's a couple renderings in here already, and if I click save to project, it will just add to this one to that list, so I usually like to keep the name of the file it suggests but then add a description of the settings that I chose, so this one was medium.
It was 750 pixels by 450 pixels, and I adjusted the exposure. Now, if you want, you can actually write exactly what you changed on the exposure to record that, but you don't actually have to do that because there's another way that you can save the exposure and you can actually save it directly to the view. Now, the other option here is to export this as an image file, so if I click export, this just takes me out to the hard drive where I can create this rendering, and I usually like to name these the same way, and I'd prefer to use the png format for most of my renderings.
Now, there's actually a difference here. If you choose a format like jpg, then it will actually render out the background that you see here, so in this case, we would just see that horizon in the background. If you choose png, then what will happen is all of the windows in all of the background part of the image will become transparent, so you can later open this in an image editing program, and you'll have the benefit of those areas being transparent portions of the image, so I'm going to make sure I'm choosing png right here, and I will save that to my exercise files folder, so once you have images that you save to the project here, you can actually place those on sheets and use them directly in your projects, so if I just close my render dialogue right here, I can open up that one that I just created, and now it's just like an image that's been inserted into the file, and then the one that I actually saved off through the hard drive is an actual image file that I can open up and manipulate in other software, so in the next movie, we'll look at what we can do with that png file that we've created.
- Creating 3D views and 3D cutaway views
- Adding details to the model
- Creating and editing materials
- Working with the sun system
- Working with lighting groups
- Configuring render settings
- Preparing a cloud render
- Creating a walkthrough
- Rendering a plan