You can generate a cubic environment map from six images using the isixpack utility. Mantra also lets you automatically generate cubic environment maps for an object during rendering.
Mantra also supports a cubic environment map stored as standard image files (
.exr) but this format is limited to 1024×512 pixels and has poor anti-aliasing compared to
.rat. You should use
.rat textures instead.
The basic idea behind a cubic environment map is to render six images from the perspective of the object you want to apply the map to (i.e. up, down, forward, back, left, right), and then combine them using
isixpack. You can apply properties to an object that tell mantra to automatically generate a cubic environment map for the object when it renders.
Select the object.
In the parameter editor, open the Gear menu and choose Edit Rendering Parameters.
In the For rendering tab, open the Mantra X.X folder.
Add the following properties to the object’s parameters by dragging them to the list of parameters in the middle pane, or select them and click the right pointing arrow.
In the Render folder: Auto-generate environment map (
In the Output folder: Output picture (
In the View folder: Resolution (
In the object’s parameter editor, click the Output tab and set the Output picture (the default
ipis a special value that opens the rendered environment map in mplay).
Click the View tab and set the Resolution for the generated images. The horizontal and vertical resolution must match (that is, the images must be square).
The Auto-generate environment maps parameter on the Render tab is on by default.
You can add extra camera-related properties for more control over the rendering of the environment map, such as the following:
The object itself is automatically made invisible in the generated images.
Aperture and focal length properties will be ignored since mantra specifies these so the 6 images stitch together properly. When generating an environment map, focal length will be 1.0 and aperture will be 2.0 (giving a field of view of 45 degrees).
The resolution override properties do not apply to environment map generation. Only the resolution parameter is used.