UV here refers to the abbreviation of u, v texture mapping coordinates (similar to the x, y and z axes of the spatial model). It defines the position information of each point in the picture.

UV accurately corresponds each point on the image to the surface of the model object. The gap position between points is smoothly interpolated by software. This is the so-called UV picture.

Extended data:

This method is used for paper, notices, book covers, etc. -That is, an object with a flat surface. The disadvantage of plane projection is that if the surface is uneven or the edge of the object is curved, it will produce undesirable joints and deformation as shown in Figure A. In order to avoid this situation, it is necessary to create an image with alpha channel to cover the adjacent plane projection joints, which will be very tedious work, so don't use plane projection for objects with large thickness and uneven surface.

For a cube, it can be projected in X and Y directions respectively, but pay attention to the fusion of edges and seams. Alternatively, seamless continuous texture and cube projection can be used. Most software has the function of automatically scaling the image to match the surface. Obviously, if your image is different from the surface shape, automatic scaling will change the scale of the image to match the surface. This usually produces unsatisfactory results, so measure the size of your object before making a map.