Octane Standalone Documentation

The Sample Position node samples the screen-space X and Y position and converts it into an RGB color with R being the X screen position and G being the Y screen space position. These values are mapped in the range of -1 to +1 and the center of the render viewport is the origin (0,0). In figure 1, the Sample Position node is used to distribute a gradient over the surface of an object dependent on the screen space.