Introduction to UV mapping介紹UV (貼)製圖

UVs (pronounced U-VEEZ) are two-dimensional texture coordinates that reside with the vertex component information for polygonal and subdivision surface meshes. UVs exist to define a two-dimensional texture coordinate system, called UV texture space. UV texture space uses the letters U and V to indicate the axes in 2D. UV texture space facilitates the placement of image texture maps on a 3D surface.

UVs是2維結構的座標，其資訊存於多邊形與(細分)表面網格上的頂點。UVs主要用於定義出2D座標結構座標的體制，這又可叫做UV材質(作業)空間，其使用U和V來表示2D的軸向。Uvs是便於圖形材質去佈置映射在3D表面上。

 

UVs are essential in that they provide the connection between the surface mesh and how the image texture gets mapped onto the surface mesh. That is, UVs act as marker points that control which points (pixels) on the texture map correspond to which points (vertices) on the mesh. Textures applied to polygon or subdivision surfaces that do not possess UV texture coordinates will not render.

UVs是必需的要素，其提供一個表面網格以及圖形材質如何映射在表面網絡上的連結。UVs的作用像是個標記點，控制材質圖像的點(像素)符合到網格的點(頂點)。沒有處理UVs的多邊形或細分表面，材質是不會彩現。

 

Although Maya creates UVs by default for many primitive types , you’ll need to rearrange the UVs in most cases, because the default arrangement will usually not match any subsequent edits to the model you may make. In addition, the location of the UV texture coordinates do not automatically update when you edit a surface mesh.

雖然可用MAYA內定原始類型新建UVs，但大部份狀況是需要你重新再整理UVs配置地，因為內定的佈置通常不會"符合對應"對到後來對模型的編輯。另外，UV結構的座標所在位置也不會自動更新到表面網格。

 

In most cases, you map and arrange UVs after you have completed your modeling and before you assign textures to the model. Otherwise, changing the model will create a mismatch between the model and the UVs, and affect how any textures appear on the model.

在大部份的狀況，要做的圖貼及佈置的UVs是在完成模型之後，以及在配置材質給模型之前。或說，改變模型會造成模型與UVs不吻合，也影響所有材質在模型上的顯示。

 

Understanding the concept of UVs and how to map them to a surface, and subsequently lay them out accurately is essential for producing textures on polygonal and subdivision surfaces when working in Maya. Understanding how UVs work is also important when you need to paint textures, fur, or hair onto a 3D model.

使用MAYA工作時，了解UVs的概念及如何去映射到表面及之後的準確地配置它，是對製作多邊形與細分面的材質必需的要素。

 

UVs and texture mapping

Texture mapping polygon and subdivision surfaces in Maya differs from how you texture NURBS surfaces.

在MAYA中，對多邊形的材質製圖與NURBS面是不相同的。

 

For NURBS surface types, each surface mesh is defined as a four-sided square or rectangular patch that has specific U and V directions. For NURBS surface types the texture coordinates (UVs) that control the placement of a texture exist by default and are implicitly connected to the control vertices. When the control vertices get repositioned, so do the positions of the corresponding UV texture coordinates. Any textures mapped to the surface are also affected as a result. That is, moving a CV will affect how the texture map appears on the NURBS surface.
對NURBS曲面型式，每個曲面已清楚分成一個四邊方塊或矩形貼片，其已有U與V的方向特性。NURBS曲面的VUs存在沒履行或暗式性的連接在控制點，當控制點重新定位時，其亦作用在UV編製的座標位置，任一材質圖映曲面亦影嚮結果。移動CV將影嚮材質貼圖在NURBS曲面的顯示狀況。

 

For polygon and subdivision surface types, the shape of surface meshes is usually much more irregular compared to NURBS surface types. Texture coordinates (UVs) associated with these surface types do not always exist by default, and so must be explicitly created, and subsequently modified in most cases, so that the surface mesh can accommodate a texture map.

對多邊形與細分面型式，其外形通常比NURBS來的更多的不規則。UVs關聯到表面樣式沒有執行不總是存在的，如此在其編修之後必需要準備地創建，致使其表面網格可以容納一個材質貼圖。

 

UV mapping UV製圖

 

The process of creating explicit UVs for a surface mesh is called UV mapping.

處理一個表面網格對其做詳儘UVs，這製程叫UV製圖(貼圖)。

 

UV mapping is a process whereby you create, edit, and otherwise arrange the UVs (that appear as a flattened, two-dimensional representation of the surface mesh, over top of the two-dimensional image to be used as a texture as it appears in the UV Texture Editor.

UV製圖是依據新建、編輯，或另外UVs配置。其UVs被展平地，而成2維的表面代理。在2D圖像圖像上，將其習慣當成一個材質的呈現在在UV結構編輯器中。

 

The UV mapping process results in a correlation between the image and how it appears as a texture when mapped onto the three-dimensional surface mesh. UV mapping is a critical skill to master for accurate and realistic textures on polygonal surfaces.

UV製圖的製程產生一個圖像及其結構(材質)如何圖映在3維多邊表面上的呈現的關聯性。UV製圖是精通一個材質準確地、可行的在多邊形表面的必要技術。

 

• You create UVs by mapping them onto your surface mesh using a variety of options. For more information see the Related topics section below.

創建UVs經由圖映表面網格是有多變的選項，更多的資訊看下面幾個相關主題。

 

• You view and edit UVs using the UV Texture Editor. You can display the texture image as a background image to let you more easily correlate the UVs to the texture. The UV Texture Editor provides many useful tools for laying out and manipulating the 2D representation of UVs. For more information see UV Texture Editor overview.

觀看及編輯UVs使用UV結構編輯器。也可顯視材質圖像在背景，這可讓你更容易聯連UVs與結構(材質)。這個編輯器提供很多有用的工具去配置及操作2D的UVs代理。

 

Note提示：
You only need to be concerned about UV texture coordinates when you want to apply a texture map to polygons. UV mapping is not necessary for creating and reshaping polygon and subdivision surfaces.

當要將一個材質貼映到多邊形時，需要連結到UVs。UV製圖在創建及重塑多邊形及細分面時，不是必需的。