Có hai loại bản đồ bình thường, không gian đối tượng và không gian tiếp tuyến: bản đồ không gian đối tượng này được sử dụng cho các đối tượng nondeforming, chẳng hạn như bức tường, phi thuyền không gian, thùng rác, và như thế. Họ được tính toán dựa trên không gian đối tượng địa phương của đối tượng. | bump and normal mapping 601 There are two types of normal maps object space and tangent space Object space maps These are used for nondeforming objects such as walls spaceships trash cans and the like. They are calculated based on the local object space of the object. Up in object space means toward the top of the object. If the object is rotated upside down in world space the top is still the top so a robot s head is still the top of the object in object space even if it s hanging upside down. Tangent space maps These are used for deforming objects such as characters. Tangent space maps record the normal s vector relative to the object s surface. In tangent space up means up away from the surface of the object. Tangent space maps appear more blue and purple since the direction in which the normal is being bent is always relative to the surface along the tangent space z-axis. The z-axis corresponds with the blue channel XYZ RGB . Object space maps on the other hand have more variation in color. In practice most artists use tangent space maps for everything. In fact prior to Maya 2008 tangent space maps were the only type of normal maps that Maya supported. Tangent space maps actually work well for both deforming and nondeforming objects. The most common way to create a normal map is to use a high-resolution detailed version of the model as the source of the normal map and a low-resolution version of the model as the target for the map. The difference between the two surfaces is recorded in the colors of the map which is then used to alter the appearance of the low-resolution model. This is a typical process when creating models for games where low-resolution models are required by the real-time rendering engine but the audience demands realistically detailed objects. Creating Normal Maps In this exercise you ll create a normal map for the giraffe. A high-resolution version of the model will be used as the source of the map. To create a normal map in Maya you ll use
