This is the view you see in your leg when in cockpit you look left-down view. It is a GIF file called Kneemap.gif in the campaign directory.
Resolutions can be 256×256, 512×512, 1024×1024 and 2048×2048. Bitdepth 256 colors.
In SP 4.2 the kneemap was however 1536×1536 resolution which was odd.