Understanding UV Layout Creation
Ever wondered what makes a stunning 3D Model a visual treat, what makes it appealing and attractive is it only the shape? By default a finished 3D model is no more than a blank canvas, most 3D packages will display it as an evenly lit shade of gray, no reflection no color no texture. So let’s understand what goes in transforming a blank grey model into a detailed stunning character as it appears in the final render. The overall process of adding details to the 3D Model including UV layouts, texture mapping and shader is called Surfacing. In this article let’s look at the basics of UV layouts in Surfacing process.
The process of adding color to a 3D model by projecting a 2D image onto its surface is called texture mapping, still in order to apply an appealing texture map to the surface of a 3D model it first needs to be unwrapped and given a functional UV layout for texture artists to work with.
UV layout could well be understood as the visual representation of a 3D model flattened onto a 2D plane / surface i.e. representation of 3D model in x, y and z axes in 2D surface with x and y axes. Each point on the 2D plan is called a UV and represents a vertex on the 3D model. Let’s understand the concept of unwrapping a model in a simpler way with this example – imagine a 3D cube & think about the shape one need to cut into the paper in order for it to properly fold into a cube; it probably look like a cross, four units high and three across. Now understand that if paper cube were a 3D model, every fold would be an edge, every corner would be a vertex and every flat area would be a face.
Technically we can say that it’s the process of assigning each polygonal face a set of UV coordinates in 2D plane. These UV coordinates are layed out visually and exported as a square bitmap image with a resolution ranging for 512 x 512 pixels to all the way 6000 x 6000 pixels.
Usually designers follow three phase procedure for laying out a model’s UV coordinates
• As the first step of laying out a model’s UV coordinates the designer selects a group of faces on the model and applies auto projection to those faces to provide a basis to work from.
• Realistically speaking as most surfaces are not perfectly flat or cylindrical, automatic mapping techniques rarely give a satisfactory result as a result, designer would have to tweak this manually by moving around UVs the way a modeler would push and pull vertices.
• As the desired result is creation of logical and well organized UV layout this process is repeated for all the polygons on the model. The Designer in this phase would go about arranging or even merging UV groups to eliminate seams.