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Twilight is a very popular and inexpensive third-party renderer for SketchUp. This course shows how to create highly realistic 3D architectural drawings (including interior/exterior elements) with the lights, materials, camera, and render options in Twilight. Author Brian Bradley explains the importance of reflectance in materials, and shows how to manage and save rendering presets, how to correct for perspective, tone, and exposure in the camera, and how to create a variety of material types. The final chapter covers rendering your complete arch-viz scene for a couple types of output, including animation and composites.
Compositing is very much a part of the modern rendering pipeline. Oftentimes, it maybe impossible to bring a project to completion, or at least completion on time, without the compositing process playing a hand. In this video, we are going to take the passes we have rendered out of the Twilight render engine and make use of them inside of Photoshop. You can of course make use of any compositing application you like. So let's bring our four images into Photoshop. Let's come to the File menu > Open, and we just need to make our way into our Exercise_Files folder.
Once there, we can come into Model_Files/Ch06/Renders, and here you can see the four images that we need to work with. So I am just going Ctrl+Select our Alpha, Beauty, Depth, and RGBMask options and then click Open to bring them into Photoshop. The first thing I want to do is consolidate all of my separate images into a single document, so I am just going to hold down the Alt key and double-click the Lock icon for our RGBMask layer. Then I am going to come up and select the Move tool, left mouse-click in the document window, and drag this up to my Beauty tab.
Once here, I can just come back into the document window, hold down the Shift key to register or center my image, and then just release my left mouse button. We will get a warning dialog telling us that the bit depth of our two images is different. This is absolutely fine. We can just click Yes to proceed and then OK. Of course, we want to do this for our depth render, so let's Alt+Double-click, left-mouse-click, drag up to the tab, back into the window, hold Shift, and then release. And finally, our alpha mask layer, Alt, double-click, drag it in, hold down the Shift key to register, and again just Yes and OK to our warning dialogs.
Now, the first thing I just want to give attention to is my Beauty render, so let's turn those layers off and just focus on this for a moment or two. At this moment in time, the render I am seeing inside of Photoshop here is not the one I saved out of the Twilight Render dialog window. In there I had a nice exposure setting, a nice gamma adjustment, and everything in this interior looked bright and airy. Here we have a very dark, very saturated image. This is just simply a matter of how Photoshop reads floating-point image files. You see, once it recognizes that an incoming image is in a floating-point file format, it will assign an RGB linear color profile to it.
This means we get the look that we're seeing at this moment in time. Not to worry though, fixing things in Photoshop very simple indeed. All we need to do is come up to our Image menu, into the Adjustment options, and we can apply an Exposure command. Now of course we could apply this as an adjustment layer if we wanted to. In here we just need to use the values that we had set up inside of Twilight's tone mapping controls. So 1.7 was our Exposure in this particular case, and we had a Gamma adjustment of 1.25.
Once we click OK, you can see that everything once again looks nice and bright and airy. Now we are ready to apply our fake haze effect using our depth render. First though, I just want to rearrange my layers stack a little bit, so I am just going to drag my RGBMask up to the top and now we have everything where we really need it. So let's come and turn on our depth render layer and just select it, because we are going to be applying some operations to it. To start the ball rolling as it were, we first of all need to change this particular layer's blending mode, so I will come up to the Blending Mode dropdown and select the Linear Dodge (Additive) option from there.
Now of course, not a lot appears to have happened. In fact, you probably will have noticed that this particular depth render doesn't look like the same image that we saved out of our Twilight Render dialog. Well, again this is because we did save this particular image in a floating-point file format. This means that Photoshop has once again linearized all of the colors. But we can fix this just as easily as we fixed our beauty pass. So let's come back up to our Image menu, into the Adjustment options. This time we want to apply a Levels command.
As we want to push this Depth Render effect away from our camera, let's just take our Gamma, or midtones, slider and just drag that to the right to crunch things down a little bit. And you can see that we can very nicely push this away from the camera. We don't want to go too far, because we are going to work with our layer's opacity. So let's just drag that to around about there and then just accept that. Now, we just want to drop the Opacity of our layer down, actually by quite a bit. So let's take this down to something around about 2%, and if I just go and disable the layer, you can see that we've just added a little bit of a subtle atmospheric effect inside of our interior space.
The next pass or element we will use is our alpha mask. We are going to use this to color correct our sky. So let's enable the layer and then just select it. I do want to say at this point that there are probably a half dozen different ways that we could use this alpha mask render to mask out our sky and then apply a color correction to it. The steps that we will take here are just one of the options available to us. So, with my alpha mask showing in the window, I'm going to use the Ctrl+A keyboard shortcut to select everything that is visible.
I am going to use Ctrl+C to copy this particular layer. Then I am going to come into the Channels palette. I am going to come all the way down to the bottom and click on the Create New Channel icon, and then I'm going to use Ctrl+V to paste my alpha Mask render into that alpha Channel. Now I can use Ctrl+D to deselect, enable all of my channels once again, and then when I come back into my Layers palette and just click on my Background layer, you can see that that strange coloration inside of our own mask disappears. Now of course to see the color correction taking effect on our sky, we are going to have to disable our alpha mask layer, and then we want to come up to the Select menu and come down and use the Load Selection command.
You can see that the channel is already selected as Alpha 1, which is the new channel that we created. So we can click OK, and you can see that that mask is loaded as a selection. We are currently selecting the wrong aspects of our image though, so let's go back up to the Select menu and just choose the Inverse command. Now, if I come down and just apply the Levels Adjustment layer, and then if I just take my Midtone slider and slide it to the right, you can see that we do indeed darken our sky quite nicely. You can also see that these reflections in our window geometry start to become a little more apparent as we just take that coloration or deepen the coloration in our sky as well.
And just to test how much of an effect we've made, we can just go and disable our Levels Adjustment layer. You can see we've made quite a difference to how our sky is looking there. So time to move on to our final rendered element, and that is our RGBMask. So let's just go and again select that layer and enable it, just to see what we created inside of Twilight. Here you can see we have our three pure RGB--or red, green, and blue--colors. Now of course, we could use the magic wand to select these colors. It would be very simple, very easy, because of the purity of the coloration in the rendered image, but I am just going to show you another way that we can go about selecting things here.
If we just come into Channels palette, you can see we have our Red, Green, and Blue channels, and because the colors we used were pure, they are the only thing showing up inside each of these channels. What we can do then is holding down the Ctrl key, we can for instance Ctrl+Click on the thumbnail for our Red channel. What will happen now is if we just come back into our Layers palette and just turn off our mask layer, you can see we have indeed selected only that single element inside of our Beauty image. Of course, what we've forgotten to do here is to turn on our R, G, and B channels, so let's do that and then come back into the Layers palette, because I want to select my Beauty pass on my Background layer and just apply again another Levels command or Levels Adjustment layer to it.
What we can do now is brighten or darken the selected elements in the scene, and I am just going to artificially darken them, just so you can clearly see the effect that this particular mask and adjustment layer combination is having. And again, to just see how the effect is working, we can go and disable and enable that layer as we like. Of course, we can use the other colors inside of this mask in just the same way. We just Ctrl+Click on the particular channel that we want to load as a selection, come back into our Layers palette, and then we can just apply color correction operations to that selected portion of our image.
Now of course just because we are making use of these compositing elements that we've rendered from Twilight, we don't want to make it seem as though we are suggesting that Twilight isn't capable of producing a final high-quality rendered image on its own, or straight out of the box as it were. It most certainly is. Oftentimes though, the time and the energy that it would take to really force that to happen means that we are being neither as productive as we probably could be, nor are we necessarily getting the best end result from our scene. Sometimes it just makes sense to make use of the specialized compositing passes that the Twilight render engine makes available to us.
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