Texture Map
Horizon’s secondary ability is to use an image layer as a texture map that is projected onto the inside of the sphere. This works fine for cloud images that have no identifiable geometry, but for a backdrop of a landscape, seascape, or cityscape to appear properly, the image must be pre-distorted and specially prepared for Horizon. Unfortunately, the feature that prepares an image texture is missing from Horizon. The names of programs that can create or prepare an image for use in Horizon, as well as instructions for preparing an image, are notably absent. In the online tutorial, the developer of the program admits that the beta version of Horizon only had the gradient capability, and image texture mapping was added at the request of the testers.
What could have made Horizon useful and more easily justified the asking price would have been to include a library of a hundred or so prepared texture maps for various kinds of skyscapes, weather patterns, times of day and so forth.
Without this library of images, you need some 3D program like 3DS Max, Lightwave, Maya, or perhaps Bryce or Vue to create the 3D model of the sky dome from which to render the image that Horizon requires. A tutorial showing how to generate such an image from an Open Source 3D package, such as Blender, would have been nice as well, for those who don’t have the many-hundreds to many-thousands of dollars to spend on a commercial 3D package.
Another area where Horizon is lacking is in having controls for applying the texture map to the sphere surface. In most 3D packages there are usually between 4 and 6 different methods to apply a flat texture to a curved surface, each method producing different distortions and yielding different results depending on the geometry of the original image. They could have included a pre-processor to distort and position the background image layer onto the sphere interior, giving better control. As far as I could tell, Horizon is limited to a single projection method and two controls that specify the expanse of the mapping – up to 360 degrees around and up to 180 degree up-and-down.
Horizon does utilize the mask from the background layer, enabling the texture to be faded out in areas. I’m not sure how this feature is useful.
Performance
If all you are looking for is a simple way to get a curved gradient in the background of a composition so that you don’t have to worry about the details of coordinating a flat gradient layer with the camera in After Effects, then Horizon is quite useful. It does a great job in this specific application and it doesn’t have a lot of unnecessary features complicating setup.
If you are looking for a method for importing sky textures into After Effects that you have created with a 3D rendering package, then this might do the trick, but you better test it first. Because there isn’t enough information available to know if the output of any specific program will be compatible with the projection method used in Horizon.
If you have a fully featured 3D animation package then you should consider whether animating the 3D elements and compositing them inside the 3D package might not be a better workflow than using Horizon in After Effects.
If you are looking for a full-featured sky generator – this isn’t it.
