If you are a 3D designer using Lightwave, 3D Studio Max, Electric Image, or any other 3D application, you can create your own Virtual sets for use with ULTRA right now.
This tutorial will show you how to save images from your 3D application for use with ULTRA, and how to create sets with “B-Source” video monitors and foreground objects. Copies of the files used in this tutorial are found in this zip file.
The first step is to model and build a scene. For the sake of this tutorial, I kept my scene very simple: I used 2 planes, one for the floor, and one for the wall. I also brought in some off-the-shelf models: a chair, and a big-screen television.
fig 1: A very simple 3d scene file
The first element to create is the background. Since I wanted the chair to be a foreground object, I “hid” the object by turning it off in the scene.
In order to make the TV screen assignable in ULTRA, I needed to apply Alpha to the surface of the screen. Depending on your 3D application, there are a number of ways to do this. In my case, it was easiest to create a plane, assign Alpha to the plane, and then position it in front of the TV screen. I then rendered the image to a 2D format that supports an alpha channel, like a 32-bit BMP, PNG or TGA file. I called this image “Background.”
NOTE: This step could also be done using a program like Photoshop by cutting out the screen from the 2D image file, and then saving the image back out with the Alpha channel. Both methods achieve the same result.
fig 2: The isolated background element, with an alpha channel in the TV screen.
To make the chair a foreground object, I needed to render the chair as a separate image, keeping the positioning, but isolating just the chair over an Alpha background. I created a new full-screen plane with Alpha, and placed that behind the chair but in front of the back wall and the TV set. I rendered out the image to a 2D image with an Alpha Channel, and called it “Chair.”
fig 3: The foreground layer over an Alpha channel
In ULTRA, I brought in Suzy’s “Wide, Standing” input clip. Then, I dragged in the Background image to the background icon. I set the key, adjusted transparency and Alpha curve a little bit, and I cropped the lighting stands out.
fig 4: The initial shot of Suzy keyed over the background layer
For my Virtual set, I used the Basic set called Simple Keyed with B. This places the B source behind the Background image. Keep in mind that the B-source needs to be positioned correctly to show through the hole. It won’t be visible initially. To position and size the B-source, I selected the B-Source Icon, and went to the Scene tab.
fig 5: Adjusting the B-Source position and orientation to fit the TV screen
In the Scene tab, I used the controls for Input Position in Scene to reposition the B-source clip. Holding down SHIFT resized the B Source, and let me make it fit into the TV screen. Since the TV is at a bit of an angle, I also used the Input Orientation control to adjust the angle a bit.
fig 6: The B Source properly positioned into the TV
Overlay, and using the Scene tab, I positioned the chair where I wanted it in the foreground.
Once the scene is set up, make sure and save the session file. That way you can re-use the overall set without having to deal with the individual elements each time. Just drag and drop in a new Input Clip, set the key, and you’ll be good to go!