Warps are the result of resampling and realigning the camera images onto regular areas (called skycells) on the sky (basically aligned N-S, E-W). How this is done depends on the particular tessellation. Different surveys may have different tessellations. A warp will generally consist of several different OTAs, therefore there are gaps between the OTAs, as well as the smaller gaps between the cells. Warps are astrometrically and photometrically calibrated.
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Example of a single warp (left) and stack (right) of a galaxy at Ra=23:41:52 and Dec=-08:38:54.05