background
#
The background
object defines the background of the scene. When you select a background, you are defining not only the image that appears behind the actor, but also which ambient light sources are casting light on your scene, such as lamps, light bulbs, or the sun.
The background
object contains the following fields. You can click on a field to learn more about it:
"background": { "id": //The UUID of the specific background that you want to place in the scene "transparent": //Whether the background is visible or transparent "rotation": //The orientation of the background relative to the camera and the actor }
Note
The background object is required for all datapoints that depict a visual-spectrum image. It should be left out if your datapoint depicts an image under near-infrared lighting.
id
#
string
The id
field selects a background from Datagen’s catalog of available backgrounds. The background that you choose provides not only an HDRI background image, but also an appropriate collection of light sources. For example, if your background image includes the sun, we will define a light source at that location and model the effects of direct sunlight on the scene, including reflections and shadows; the same is true for streetlamps, light bulbs, and other types of lighting that may appear in the image.
Tip
Datagen offers a unique background with lighting that simulates cross-polarization photography. To generate a datapoint with this background, set the id to 151c5b4a-3022-49a6-91f0-8749958e7ab7
.
Tip
To download a CSV with a complete list of background UUIDs, click here
Backgrounds are categorized…
by time of day
Morning
To download a CSV with a complete list of available of backgrounds with morning lighting, click here
Evening
To download a CSV with a complete list of available of backgrounds with evening lighting, click here
Night
To download a CSV with a complete list of available of backgrounds with nighttime lighting, click here
by location
Indoor
To download a CSV with a complete list of available of indoor backgrounds, click here
Outdoor
To download a CSV with a complete list of available of outdoor backgrounds, click here
Sample usage
A sample id field and its location in the data request
In the JSON hierarchy of the data request, the
id
field is found here:{ "datapoints": [ { "background": { "id": "101a0478-03e7-4e93-a33d-9bc22f6dbdbn4", } } ] }
transparent
#
Bool
The transparent
field defines whether the background is visible behind the actor or not. If you make the background transparent, all background-associated light sources (such as the sun or streetlamps) will still cast light on the scene, but the actor will be the only visible physical object.
Sample usage
A sample transparent field and its location in the data request
In the JSON hierarchy of the data request, the
transparent
field is found here:{ "datapoints": [ { "background": { "transparent": false, } } ] }This value will generate a scene with a visible background.
rotation
#
64-bit float
The rotation
field sets the orientation of the background relative to the actor in the scene.
When you select a background using the id field above, you are selecting a full background image and series of light sources that wrap 360° around your actor. The rotation
field is useful for ensuring that a specific part of the background is directly behind the actor, or ensuring that the sun casts shadows in a specific direction, or ensuring that light sources are in specific locations relative to the camera lens.
In the above examples, notice how the rotation of the background affects the following:
The angle between the actor and the fence behind her
The different locations of the darker green segment of the tree behind her.
Subtle shifts in the shadows on the actor’s skin, particularly noticeable on the right cheek and left collarbone
The changing location of a light source behind the camera, which can be seen reflected in the actor’s eyes
Sample usage
A sample rotation field and its location in the data request
In the JSON hierarchy of the data request, the
rotation
field is found here:{ "datapoints": [ { "background": { "rotation": 235.0 } } ] }This value will generate a background that has been rotated by 235 degrees.