Hello everyone! I am the master of up: basic modeling
Today I mainly talk about some basic knowledge related to UV.
1. Brief introduction of UV exhibition
It refers to flattening the surface of a 3D model into a corresponding 2D coordinate image.
In this way, the 3D model can correctly display the 2D material we gave it according to the coordinates.
To put it simply, the 3D model is divided and processed into a plan view, and then it can be exported to planar software for drawing textures.
2. Basic rules
* Try to sew the large faces together, don't make the UV look too fragmented.
** Minimize the distortion of the 2D image so that it conforms to the law of the 3D model.
*** Place UVs reasonably and use overlapping UVs.
3. Fundamentals of UV space
*It is a grid based on 0~1, and the smallest unit is 0.1 unit cell.
A UV map is to convert the X, Y, and Z coordinates of a 3D model into a 2D UVW space.
** According to the modeling tool and mapping tool in the software
The 3D X coordinate corresponds to the U direction of the 2D coordinate, the vertical Y coordinate corresponds to the V coordinate of the 2D coordinate, and the Z coordinate corresponds to the W coordinate.
***Notice:
The flattened polygons of the model need to be placed in the UV grid, so as to ensure accurate texture information in baking and rendering.
So why use UV coordinates instead of standard projected coordinates?
Usually, the most standard method for texture mapping of objects is to project textures in planar (plane), cylindrical (cylindrical), spherical (spherical), cubic (square box) coordinates.
4. Tangents and Seams
* The tangent vector is actually the rate of change of the model space coordinates relative to the U value component
The bitangent vector is the rate of change of the model space coordinates relative to the V value component.
** It is impossible to have no seams when developing UV, but the seams of UV should be placed in the "hidden" part of the model.
For example, the opening of the head should be behind the head, the thigh part should be placed on the inner side of the thigh, and so on.
When drawing textures, most of them use PS to draw. As for the UV seams, BodyPaint3D should be used to draw.
Textures at UV seams are easy to do with BodyPaint3D.
*** Notice:
UV cuts and seams are very different between organic models (that is, models that don't have hard edges like creatures) and hard-edged models (such as mechanical models).
Because hard edge models need to cut more UV edge seams to reduce distortion. This also prevents errors in normals and baking.
In addition to high poly and smoothing, normals also help with better shading. In order to ensure that it can be used in hard-edged models, some precautions need to be taken when cutting UVs.
all right! Thank you for reading. If you have any questions, you can directly contact the editor . I hope it will be helpful to everyone.