Control Latitude and Longitude in GIMP Little Planet

The GEGL Little Planet filter in GIMP transforms 360-degree equirectangular panoramas into spherical stereographic projections, allowing you to create miniature planet or tunnel effects. Controlling the latitude and longitude parameters determines the precise center of focus, orientation, and viewing angle of your projected scene. This guide explains how to locate these controls within GIMP's interface and adjust them effectively to compose your final image.

Accessing the Filter

To use the filter, open an equirectangular panorama (typically an image with a 2:1 aspect ratio) in GIMP. Navigate to the top menu and select Filters > Map > Little Planet. Ensure the Preview box is checked so you can observe your changes in real time.

Controlling Longitude (Pan)

In the Little Planet dialog, longitude is controlled by the Pan slider.

  • Function: The Pan parameter rotates the source panorama horizontally along the equator, measured from -180° to 180°.
  • Adjustment: Dragging the slider left or right rotates the planet clockwise or counterclockwise. This determines which landmark, building, or section of your horizon faces the top or center of your composition.
  • Precision: Click directly on the numeric input box to enter an exact degree value, or use your keyboard's arrow keys for single-degree increments.

Controlling Latitude (Elevation)

Latitude is controlled by the Elevation slider (often labeled as Tilt in generic stereographic projections).

  • Function: The Elevation parameter adjusts the vertical camera angle relative to the horizon, ranging from -90° to 90°.
  • Creating a Little Planet: Lowering the slider toward negative values tilts the projection downward, pulling the ground (nadir) into the core to wrap the horizon around the center into a sphere.
  • Creating an Inverted Tunnel: Raising the slider toward positive values tilts the projection upward toward the sky (zenith), creating a hollow circular frame or "rabbit hole" where the sky sits in the center and the ground borders the outer edges.

Balancing with Zoom and Roll

Latitude and longitude adjustments directly influence distortion at the edges of the frame. After setting your Pan (longitude) and Elevation (latitude):

  • Use the Zoom slider to crop in or out, ensuring the entire circular planet fits within the canvas without clipping important details.
  • Use the Roll slider to rotate the final 2D plane without changing the underlying latitude or longitude coordinates.