When developing art assets for X-Plane (specifically, any image file that will be attached to an X-Plane object, facade, or terrain overlay), note that the image must use powers of 2 in its resolution.
This means that an image can have a width or height (in pixels) of:
Images used with objects and facades do not have to be square; a facade image could have a resolution of 512 x 1024, or 1024 x 2048, or 2048 x 512, and so on.
However, images used for polygon overlays (such as orthophotos) have the additional requirement of being square. Thus, orthophotos may have the following resolutions (in pixels):
- 256 x 256
- 512 x 512
- 1024 x 1024
- 2048 x 2048
The only images that can be used in X-Plane without a power-of-2 size are those used in the 2-D panel/instrument system.