The Documents of Stage Hands
Texturing A Dyntopo Character
UV Layout from a Retopologized Model Vs UV Layout from a Decimated ModelIn the preceding image, the UV shell of a character’s head firstly depicts the “ideal” retopologized version compared to the decimated version. But as you can see both UV layouts yield results, for a baked AO map, that are acceptable for importing into a photo manipulation program.
The main point worth noting here, is that when taking your model’s texture map into an image manipulation program such as the GIMP or Photoshop it is generally considered best practice to ensure that the model’s UV shells are layed out in a way that best represents what the model looks like.
For example, when unwrapping a head the model’s UV shell (of the head) should look like a 2D representation of what that character’s 3D head would look like if pelted.
In the above image it is quite clear that we are looking at the UV shells for a character’s head. The location of the eyes, nose, mouth, forehead etc are clearly visible and placed where you would expect them to be.
Without these details being translated from the 3D application to your 2D photo manipulation software, creating or modifying a character's Texture map can become very time-consuming and even confusing.
These sort of results are not easy to achieve with automatic UV projections, and generally should be done manually.
Although the results of a decimated model’s UV layout are not as easy to predict as that of a retopologized model, the compensation is that polycount reduction can be achieved a lot faster which leaves you with more time to spend painting and or photo manipulating the model’s texture, which is ultimately the premise of what we are hoping to achieve.
Efficient Usage of Texture SpaceThe final point worth noting about a character with decimated geometry’s UV layout and that of a character with edge loops that are modelled in place, is that 0 to 1 Texture space can be used more efficiently in the latter.
For example, the above image compares two different UV layouts, the left layout is from a character with edge loops placed with intentionally, the right is from a character with decimated geometry. Notice how much texture space is lost on the decimated model in order to keep the shells representative of their 3D counterparts.
That “negative” texture space (between UV shells) is generally easier to fill when a character’s UV layout is derived from a model in a symmetrical pose such as a "T-pose".
Despite the obvious limitations of unwrapping a decimated models UV’s, it’s worth bearing in mind that this method can be used effectively for static characters or objects and that the edge loop placement resulting from decimation can also be controlled to some degree.
By sculpting creases into a character, as is depicted by the areas demarcated by the arrows in the preceding image, these seams can be retained in the geometry post-decimation.
For example, where the torso joins the hips or the arms meet the shoulders, if these creases are prominent enough when sculpted with a high polycount density ratio (in comparison to surrounding areas) they will remain evident in the geometry even after the model is decimated i.e. assuming the decimation process is halted at a reasonable level, such that the main characteristics of the model are not lost. This can effectively be used to some degree to control the model's topology which ultimately will be used to create the model's UV shells.
Furthermore, if these creases are created with careful consideration, just as is the case with UV unwrapping a character with intentionally placed edge loops for animation, the majority of this character’s seams can also be placed primarily out of sight.