Select the layer you want to apply a filter to, then select the [Filter] menu > [Distort] > [Fish-eye lens] to open the dialog box. This distorts the image on the layer by making it look as if it is viewed through a fish-eye lens. The area outside the "lens" is transparent.

Creating a perspective ruler using 3D models Load the 3D material onto the canvas and adjust it to the camera angle you want to draw. Tap the ruler icon on the 3D layer to display the perspective ruler. To use the perspective ruler on other layers, adjust the ruler's range in the Layer palette.