Spherical Mapping

The Spherical Mapping projects content outwards from an eye point in all directions. It can be used with 3D modules to project a complete spatial render of a virtual scene, or with 2D content to emit equirectangular images and videos from the surface of a sphere. It works similarly to the Cylindrical mapping, except the top and bottom are ‘pinched’ to create a sphere.

Creating a Spherical Mapping

1. In your track, create a new visual layer. These layer types can include content layers, generative layers, and effect layers.
2. Left-click on the layer in the track to open the Layer Editor on the left side of the GUI.
3. Under the Default tab, left click on the Mapping parameter to display a list of the mappings in the project.
4. A manager titled mappings will appear – this is a list of all mappings within your project. By default, all screens will be populated with a direct mapping sharing the same name, and all cameras will be populated with a perspective mapping sharing the same name.
5. Type directly into the New mapping: text field to create a new mapping. A list will appear prompting to you select the mapping type.
6. An editor with the user assigned name of the mapping will appear once a mapping type is selected.
7. Assign all screens that will be used for the mapping and enter the resolution of the content that will be displayed on the screens.
8. Edit the specific properties of the chosen mapping type.
9. Assign a piece of content to the layer in the track, and the content will be displayed on the assigned screens of the mapping in the stage and the feed output window.

Common Mapping Properties

This section explains the properties that are shared by all the different mapping types.

Filtering

Nearest - Nearest neighbour filtering. Use nearest-neighbour sampling, to disable blending between pixels when scaling. Can be used to create pixellated looks, or to ensure hard edges on certain types of content.

Bilinear

Bilinear filtering is a texture filtering method used to smooth textures when displayed larger or smaller than they actually are.

2x Multi-sample

Multi-Sample filtering can help fix issues with scaled content, but can introduce some blurriness.

Resolution

This controls the canvas size the layer renders into, in pixels. The Direct mapping type starts with a 256x256 pixel canvas and automatically sets the canvas size to that of the first screen you add.

Screens

This is a list of screens that the selected mapping type can copy content to.

1. Left-click + to open the Screens manager.
2. Left-click the Screens you want to map. This will copy the individual canvas content onto these three Screens simultaneously and will add the Screen names to the mapping object editor.
3. Left-click and drag the Screens listed in the mapping object editor to -. This will remove the canvas content from the Screens and delete the Screen names from the mapping object editor.

Mask

This points to the Texture file that defines a Mask bitmap. You can use this property to apply a Mask bitmap to the mapping canvas. Selecting this property will open the Texture object library, which shows all of the still image files saved on your local hard-drive in the DxTexture folder.

To apply a mapping mask you will need to create and import a custom still image file.

The step-by-step instructions on how to create and import a custom Population mask can be used to create a custom mapping mask. The only difference is that the mapping masks resolution should be the same as the mapping canvas. For step-by-step instructions on how to create and import a Population mask into a d3 project visit to the section Population mask in the Editing screens sub-chapter.

Alternatively, set any layers blend mode to mask to channel the layer content into the mapping mask.

Spherical Mapping Properties

Horizontal arc

Defines the angular arc that the horizontal dimension of the content is mapped over, in degrees. 360 maps over a whole sphere, 180 renders over half a sphere.

Vertical arc

Defines the angular arc that the vertical dimension of the content is mapped over, in degrees. 180 maps from the North to South poles, 90 maps from the North pole to the equator.

Projection mode

Defines the direction that the content is mapped, Outwards or Inwards. This can be thought of like a spherical equivalent of mirroring the content.

Content mode

This can be set to 2D or 3D. The 2D content mode treats whatever image it is receiving from the modules as an equirectangular image. The 3D content mode sends the required content viewpoints to 3D modules, updating based on the positional properties of the mapping, and then stitches together the returned content into a spherical image.

Avoiding seams in content

Rendering of the spherical content is achieved under the hood by rendering the 6 faces of a cube, then combining and warping them to the correct spherical output. Certain screen-space effects used when rendering the virtual scene can cause visible seams between the faces. See UE scene optimisation for tips on how to avoid this in Unreal Engine.

If some screen-space effects are required for creative reasons, it is possible to mitigate their effects and avoid seams by setting Padding and Overlap in the spherical mapping:

• Padding: This value sets a number of additional pixels which are rendered outside each face, then cut away when combining the faces. This can be used to mitigate effects such as blur which exhibit edge effects on the extremities of the rendered image.
• Overlap: This value also renders additional pixels outside each face, then smoothly blends between the pixels of adjoining faces on each edge. This reduces the appearance of seams between faces by smoothing over the join, so you don’t get a hard line.

Caution

Both padding and overlap will increase the render resolution of each face, and therefore will increase the GPU resources required to render the content. It is recommended to set these to the smallest values required to remove visible seams.