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Image Overlay and Projection Screens
The perspective window is designed to work with undistorted imagery: the perspective view always shows the view with an ideal, undistorted camera, even if SynthEyes has calculated a lens distortion value. A conventional camera view will be pulled from 360VR footage as well.
This reflects the essential difference between the camera and perspective views: the camera view shows the source footage as is, and distorts all 3-D geometry to match. The perspective view shows the 3-D world as is, and dynamically un-distorts the footage in order to make the shot line up.
Note : the distortion performed by the camera or perspective views is that specified by the distortion value on the Lens panel, typically calculated by a solve—this is different than the distortion values in the image preprocessor, which affect the imagery before it arrives to either the camera or perspective views. There's no need to compensate for image-preprocessor values, since the image already reflects them.
As an additional feature for green/blue-screen shots, the perspective view will matte out the keyed background, showing only the un-keyed actors and set. You can set up your scene to place them within your 3-D set by controlling the camera/screen distance. If you don't want this kind of keying, turn off green screen processing from the Green Screen dialog on the Summary panel.
The perspective view will also key based on any existing combined or separate alpha channel in the imagery (for example, from a third-party keyer)—be sure to turn on Keep Alpha when opening the shot or in the image preprocessor.
While you can set the distance to the screen directly, or proportionately to the world size (the default is a multiple of the camera's world size), it is most useful to have the screen dynamically scale so that it always passes through a single point, either a tracker or extra point. For example, in a green-screen shot of several people talking, you can use a tracker at their feet as a target point, so that the screen stays fixed in distance in the 3D environment, even if the camera moves closer and further away. You can position 3D objects around it and see the matted shot in their midst.
The perspective view's built-in dynamic projection screen generator works behind the scenes, so the resulting 3D meshes cannot be selected, examined, or exported.
Important : the built-in projection-screen generator is very behind-the-scenes. To adjust its settings, such as the grid resolution and distance from camera to screen, use the Perspective Projection Screen Adjust script. It affects the currently-selected camera. Settings for new cameras are loaded from a corresponding set of preferences in the Perspective section.
The projection screen mode listed in the preferences and adjust script has four settings: Never, Automatic, Locked and Always. It controls when the built-in projection screen mesh is engaged, to handle distortion, green-screening, and alpha channels. If it is disabled, the incoming image will be displayed as-is, with no distortion correction or keying. The Automatic system turns it on when the perspective view is locked to this camera and distortion, green-screening, or an alpha channel is present, and leaves it off the rest of the time, using simpler and faster image draw code to improve performance. The Locked setting generates the screen whenever the perspective view is locked to this camera.
Finally, the Always setting generates the screen all the time, even when the perspective view isn't locked to the camera. This lets you see the screen when you have unlocked from the camera, or from other perspective view windows, which can be handy for lineup with matted-out green screens, for example.
The projection screen (and the physical script-based screen described below) operate by texture-mapping a distorted grid object. The accuracy of this process depends on the number of segments (and thus vertices and faces) in the grid. For more extreme distortion, you should increase the resolution of the grid.
You can also use the Projection Screen Creator script to create actual mesh geometry within the scene that is texture-mapped with the shot imagery. As a physical mesh, it can be exported directly to other applications. Because the mesh is created once, when you run the script, it cannot be used with zoom shots, and you must manually re-generate it when the lens FOV or distortion changes.
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