Trapcode Horizon

Interface

Horizon is set up by default to use a gradient for its spherical reference, but you can switch to an image map referenced elsewhere within your composition.

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Gradient

If you're going to use an image map instead of a gradient, skip this section and proceed to the Image Map section below. If you're looking to use a gradient, this section contains controls on up to eight colors and works in two different modes:

• Style - Lines creates a gradient with horizontal color bands. The bands are all parallel to the horizon and are mapped onto a giant sphere. This means the more upward your camera movements are, the more spherical the shape will become. To remove or reduce this curvature, open the Orientation and Distort controls below and set the Straighten control to 100.
• Style - Points creates gradients that are controlled by up to eight longitude and latitude points on the giant sphere, which have parameters activated (see below).
• Point Spread determines how far color spreads from the points to which they've been assigned. (Note: This setting is only available if Style - Points is selected.)
• Colors determines the number of colors and points available to control.
• Color 1-8 point controls have four available parameters.
  • Color allows you adjust the color of the point using a swatch and palette.
  • Opacity determines the color's transparency.
  • V Angle sets the vertical angle (Height & Latitude)
  • H Angle sets the horizontal angle (Longitude) (Note: This setting is only available if Style - Points is selected as your style.)

The Gradient settings above are only activated as long as Image Map is not selected (see below).

Image Map

When a layer is selected using the Layer pop-up menu under the Image Map controls, the referenced layer is used instead of the built-in gradient.

• Layer allows you to select which layer within the current composition you'd like to use as an image map. The image then gets mapped onto a sphere with an infinite size.

Note that when a flat, 2D image is mapped onto a spherical shape, distortion will naturally
occur, that is unless the image has been specially created or adapted for use with a 3D sphere, such as a spherical map. A spherical map is a 2D image that has been pre-distorted so that it will look correct when mapped onto a 3D sphere (see right).

There are two main benefits to using special spherical maps:

• They are usually made to have no seams at any point along the sphere, even at the poles.
• Spherical maps are built to be wrapped spherically and will not look warped or stretched.

A number of vendors around the internet sell spherical or equirectilinear maps. You can also use panoramic images like those captured on a mobile device or equirectangular/longitude-latitude maps.

Regular photos can also be used, such as stitched panoramas and matte paintings (or movies), as Image Maps. You'll need to set the Coverage H and V to desired values, then set the Straighten control to 100 in the Orientation and Distort group.

H Coverage describes in degrees (0-360) how much the image map covers the view horizontally. A value of 360 means that the left and right sides of the image will meet on the far side of the sphere and will create more horizontal distortion. For an animation using a non-spherical map, where the camera does not move a great deal, you may achieve better results by limiting horizontal coverage to create less stretching.

V Coverage describes in degrees (0-180) how much the image map covers the view vertically. A value of 180 means that the top and bottom of the image will touch the poles, creating more vertical distortion in a non-spherical map.

Sampling: Your 2D image is mapped to a 3D surface. However, there is not a one-to-one correspondence between each pixel and each coordinate on the sphere because the image is stretched to fit the spherical surface. Sampling compensates for this lack of perfect correspondence and interpolates the right pixel value at each coordinate.

Horizon offers two sampling methods. Nearest Neighbor sampling is fast, because it picks the closest pixel value to the coordinate, but it can result in a pixelated effect. The default setting of Bi-Linear sampling averages pixels around the coordinate. This is slower but produces better quality.

Orientation and Distort

X/Y/Z Rotation rotates the gradient or image map relative to the camera in the scene. Rotating in X will move the gradient or image up and down relative to the camera view. Rotating in Y will move the sphere around the camera –left to right for positive values or right to left for negative values. Rotating in Z will tilt the horizon line clockwise or counter-clockwise relative to the camera.

In most cases, you should leave these values at their defaults and use the composition's camera to animate the position relative to the background. If you need to move the position of a map, or you want create motion blur in front of the camera, then you might animate or change these values.

Straighten makes all lines straight in the Gradient/Lines mode when the value is set to 100. This control is most useful with image maps that are not in the spherical coordinates format (i.e., regular photos) so you can undistort the projection of the image onto the sphere.

Scatter introduces a subtle scatter to both Gradient modes and image maps. Increasing this value to between 10 and 50 can be useful for in reducing banding artifacts in the subtle gradients created by the plug-in. (Note: This type of banding effect is usually only noticeable with subsampled codecs like DV or HDV compression.)

Motion Blur

By default, Horizon uses the After Effects Comp Settings for Motion Blur.

To adjust the amount of motion blur natively, set the shutter angle, and phase in the Composition, go to After Effects' Composition > Composition Settings > Advanced settings.

Motion Blur can be disabled by selecting Off in the Motion Blur pop-up. This overrides the layer Motion Blur switch. So, if the layer's motion blur switch is on and the Motion Blur pop-up is set to Off, then Horizon won't render a motion blur.

• Levels lets you select how many levels or time samples of motion blur to render. More levels or samples means greater smoothness, but it will take longer to render. You may need to increase the Levels value to 16 or 32 to create a smoother blur if the camera moves rapidly in the scene.