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Quite clearly, the Twilight render engine has been built around the premise of making realistic rendering as easy and painless as possible for artists who, for one reason or another, have no need to learn the intricacies of balancing the myriad parameters that may need to be tweaked in order to fine-tune a raytrace render engine. That though doesn't mean that such parameters cannot be accessed by artists using the Twilight renderer. It is just that the user interface doesn't expose them to us at this moment in time.
In this video we're going to walk you through the basic process of creating our own custom render preset. To do this, the first thing we will need to know is where our render preset files reside. This will mean we need to, first of all, locate our SketchUp installation folder. You can see we are inside our Google SketchUp install. To locate our render preset files we need to come into the Plugins folder and then of course locate and enter the Twilight folder, and in here you can see we have a RenderSettings folder.
It is in here that our Render Presets reside. Once in here, you will see options that we will be very familiar as they mimic the layout that is found inside of the Twilight user interface. So we have our Express and our Tech folders with the various subcategories of render presets held within them. Now, before we make any changes in here, I just want to jump back into SketchUp because I just want to highlight something inside of Twilight's Render dialog for you. If we just come into our Preset options here, you can see that inside of our custom set we have, well, no render presets.
We have no custom options set up at this moment in time, which of course is something that we will change right now. So let's jump back into our Render Settings folder. In this instance, I want to come into our Easy folder and I'm going to make a change to our 04_Medium render preset. Well, we're not going to make a change to this one, because obviously we don't want to break anything inside of Twilight itself. What we are going to do is first of all, make a copy of this particular file, so let's just right-click, go to Copy, then we want to come back up into our Express folder, and indeed come into the Custom option and then just right-click and paste our file in there.
Straight away, to avoid confusion, I'm going to rename this new Render Preset. I'm going to leave the 04. Medium tag on there, just so I know from which render preset I have taken this custom option. But I'm going to append the NoReverseGamma label. That describes exactly the change that I'm going to make inside of this particular render preset, and of course then we can accept those changes. Now, if we jump back into Twilight and if we close our Render dialog and then reopen it, you'll see that we do indeed have our new render preset showing up inside the Custom options.
Of course we haven't actually customized anything at this moment in time, so let's jump back into our folder and do just that. Now as we're working with XML files here, we can generally open, edit, and save them in a simple text editor application. Now in my case working on Windows 7, as I am, I can just right-click my file, choose the Edit option, and you see it will be opened up inside of Windows Notepad. You can of course use any text editor that you'd like. Obviously, we can now make changes to any of the parameters inside of this file without doing any damage to our existing Twilight render presets.
Do be careful though: if we make changes to options inside of these files without having any real idea of the expected end result, we could run ourselves into any number of render problems, not least of which would be greatly inflated render times. These files do contain controls handling every aspect of the rendering process. This of course includes controls handling the quality of our global illumination as well as our anti-aliasing options. In this instance, to keep our changes nice and simple and trackable, we're just going to change one option inside of this file.
So, if we scroll all the way down to the bottom, you can see we have this Reverse Correction and Reverse Gamma options. Now we could make a change to the Reverse Gamma value if we just wanted to tweak how much reverse gamma correction is applied to our bitmaps and our material color swatches. In this instance though I'm going to make things a little more obvious, a little more dramatic, and actually turn off our inverse or reverse gamma correction. As this is just a simple Boolean value, that means that 0 is off and 1 is on. I can just go, select that, set a value of 0, and we're done.
Now what I want to do is come up and just choose the File > Save option. Again, we do want to be careful when saving our files out. We don't want to inadvertently write out a simple text file. If we do that, Twilight will not recognize the preset. It won't in fact show up inside of the Twilight user interface. This has to remain an XML file for it to be usable. Now what we can do is just dismiss our floating dialogs, because I just need to make a couple of tweaks inside of SketchUp and Twilight before we can take our comparison render.
So let's just close our Render dialog, and I first of all want to come into my Layers dialog and just turn off our Sky Portals layer. Of course, first of all, I need to make certain that it isn't the default layer and then I can go and turn that off. We don't want to increased render times that that would give us using the Easy 04 preset. Now I can go back into my Twilight Render dialog, and I just want to go into the Camera tab and make certain that my Gamma Adjustment value is set to 1.0. That means we're just inline with the test renders that we're going to show you in Photoshop in just a moment.
Now we can come and take two renders using our Easy 04 and our Custom 04 NoReverseGamma presets. As we've already done that, we can of course just jump into Adobe Photoshop. Here, first of all then, is our Easy 04 preset. This is using the settings that we've just created inside of our SketchUp scene file. And if we just come up to our tab and switch to our Custom Preset, you can see that there is quite a considerable difference. Now, because there is no inverse or reverse gamma correction taking place on our bitmaps or our material color swatches, you can see we definitely get a very different end result.
Clearly then, parameter tweaking is available to us when we render in SketchUp using the Twilight engine. We just have to be prepared to dig a little into the render preset files, the XML files, to be able to do this. Again, just to reiterate our warning: do be sure that you have at least some idea of what effect a particular parameter change is going to have on your render before you make it. That way you'll just avoid running into any nasty surprises.
- Installing Twilight
- Adding the Physical Sun and Sky
- Employing Point, Spot, and Projector light types
- Using light emitting materials
- Managing the Quality Presets
- Positioning your scene view
- Working with the camera's Focal Length setting
- Creating diffuse, reflective, and refractive surfaces
- Rendering out an alpha mask
- Setting up a depth render