One of the new features in 3DVIA Composer 2012 is the ability to set a depth of field for a view. This is very useful to call attention to a specific area of a model in a very natural way. It also lets you add an artistic touch to a marketing image, giving it a photographic look.
The first thing you need to know is that Depth of Field only works when you have Perspective turned on in your View. The reason is simple -- without a vanishing point, there is no way to calculate how the Depth of Field is to appear in the View. So, make sure you have Perspective turned on before you play with the Depth of Field tools; without it, nothing will appear to happen. Perspective is a toggle on the far lower-right of the 3DVIA Composer application window:
Where do you find the Depth of Field tools? Look at the Render menu, and you'll see some icons related to Depth of Field all in one place:
Depth of Field is the largest button, and it's a toggle. In order for it to be effective, however, you need to Set Focal Point. This is much like single-spot autofocus on an SLR camera: you pick one spot in 3D space and that is what will remain in sharp focus. In 3DVIA Composer, you are clicking on a face of a geometry actor. The tool is fairly intuitive, and it will automatically know the Z-depth from your camera view based on what and where you click.
You will notice that setting the focal point will make a visible mark in your active View -- that's so you can see exactly where the focal point is in your scene. To hide the focal point graphic (but keep the setting) put an X in the Visible checkbox in the Depth of Field section of the Render toolbar. You can toggle it back on later if you want to see it again.
While there is an Automatic setting for Depth of Field, I never use it. If you're going to turn on Depth of Field, you are going to want to control what's in focus. Automatic will have the system move the focal point as you rotate and move the model -- I've not seen it be really helpful in my testing of the setting.
So let's take a look at how this works. This is the model and View I'm working with:
The first thing I want to do is turn on Perspective. Depth of Field notwithstanding, this one, simple setting adds realism to the View simply because in real life there is always a vanishing point. Views without perspective look artificial, which in mechanical drawing is "normal" but you'll never see a camera take an image of something without perspective (nor will your direct vision ever give you such a view).
Now that looks much more natural. I want to highlight the logo on the filter cap -- I'm selling OUR supercharger, not just anyone's. So let's turn on Depth of Field and click the closest corner of the G as the focal point. Here's the result:
You can play with the settings for the Depth of Field in the Viewport Settings. There you will find another toggle for Depth of Field being turned on or off, as well as two sliders for Level (how deep the in-focus area is) and Number of Passes (how many times the Depth of Field is rendered, where more levels equals better image quality at the expense of time). These are the settings I've used for the View that I'm working with in our example:
In real life there would be some more definition with shadows and lighting to make the image pop a bit. I could go into the different lighting and shadow settings, but that's another post. Besides, I just need to refine the image a little bit. That's why I love Ambient Occlusion -- it's a one-click image enhancer:
That's more like it! Sure, there are other settings we can play with, but I get a lot of mileage out of simply turning on Perspective, setting a Depth of Field and turning on Ambient Occlusion with the default settings. Now that you know these tools and techniques, I don't want to see any more flat isometric renderings for marketing product shots!