Adobe 25510629 User Guide - Page 69

TIP Transparency: Save any layer that has transparent regions in a format that supports an alpha channel, such as .png and .psd files. To learn more about alpha channels and how to save layers in a format that preserves transparency, see the image-editing application's documentation. Perspective: Shoot the still images that you're using for a set from the height and angle that you're using for the main subject. If you're using computer-generated graphics, design them with the camera's perspective in mind. Lighting: Light the scene from the same angle from which you're lighting the subject when shooting the input clip. Multiple angles: If you have multiple scenes with different angles of the same set, you must prepare the images from each angle. For the most consistent, realistic appearance, light all of the sets from the same absolute or global perspective. Aspect ratio: Ultra does not force images to the 4:3 aspect ratio. To achieve more advanced results: • To produce a dynamic result like those from VirtualTrak shots from the Master Sets Libraries, use the pan and zoom features. For more information, see "Panning and zooming" on page 99. • To show the input clip as an inset, create an overlay with an alpha region where you want the keyed input clip to appear, and then scale and position that clip and its background to fit in the designated space. Backgrounds There are two basic types of backgrounds: background with one or more transparent regions cut in it to show the sources behind it, and backgrounds without transparent regions. Backgrounds without transparent regions are simple to create. You can assign any image of a supported file type as a background. As a rule, you want the frame aspect ratio for the background to be the same as that for the session as set on the Output tab. For backgrounds that you use with one or more inset sources, you must create an alpha (transparency) region in the image for each inset. In Photoshop and other image-editing applications, this can be accomplished in many ways, including using masks. If the alpha region is on in a surface that is angled to the plane of the camera's lens, then you should adjust the perspective of the alpha region accordingly. You typically need to change the size, position, and possibly orientation of the inset source to appear in the correct space. For more information, see "Changing the position and scale of a layer plane" on page 92 and "Changing the orientation of a layer plane" on page 93. Creating and assigning sources and virtual sets 69