Cineversity

Hello,

I’m relatively new to Cinema 4D and have been learning on-and-off over the past year when time permits.

After taking many, many courses and tutorials to form a basic foundation of skills (Modeling, Lighting, Materials) I’ve created my first homegrown hard surface model.

In applying materials to the model, I noticed distortion in some “scratches” I’ve added to the materials which led me into the UV rabbit hole.

I’m currently taking Cineversity tutorials focused on UV unwrapping (hard surface) which makes total sense to me and I can see how it will help eliminate distortion in my materials when applied to an object.

What I don’t quite understand are the steps after a UV unwrap… I’m left with all these nice islands, but a ton of seams in my materials. Do the islands need to be “stitched” together to eliminate all the seams? Am I thinking about this totally wrong and is there a better approach to reducing distortion in materials without UV unwrapping?

Any advice/knowledge is greatly appreciated!

Thanks,

- Brian

Hi Brian,

This is quite a general question, which leaves me with: it depends, as the main answer.

UV is the “translator” between 3D based shapes and flat (2D) image information. There are shapes in 3D that will not have a seamless texture while showing no kind of distortions, just with a push of a button, if at all. To find the sweet-spot is often the key. The other direction would be to start UV mapping by defining the seams and where they can be hidden.

If you have an island, and several of them, then there is a reason for that. If the reason is in the model, then more often than not, the shape requires is. Or: the wrapping method was set so that the split was a logical result of it.

Keep in mind that many models will be hand-painted in BodyPaint3D. There the seam is less an obstacle than an equal size of the UV polygons compared to the surface. While painting on the surface, the brush-stroke resolution is more important than having more or fewer islands.

You see already a few lines into them, and it spreads widely.

You can also start by thinking of standard projections of the model. More simplified: how would you cover the object with a paper-based surface without creating wrinkles.

Organic models often have more challenges; their projections and other options (cloning) might be a way to go, to test the waters first.

In short, as mentioned, it depends.

All the best

Hi Dr. Sassi,

Thanks so much for your quick and thoughtful response.

Apologies for the broad question… I was hoping I was simply overlooking “The next step,” but as I’m learning, all things 3D are be a bit more nuanced than they seem.

I’ll try my best to clarify my question based on course I’ve been working on.

I’ve been working through the “Hard Surface Modeling UV Unwrapping” series in which a Pipe Wrench is UV Unwrapped. After unwrapping the first component of the wrench, I’m left with many, many islands and seams (see screenshot).

This is where the confusion arises…

A component of a pipe wrench would typically be made of a single, cast piece of metal. This metal may have a rough texture (bump) and some surface scratches.

If I were to use the UV map pictured in the screenshot to texture the object, the seams may be visible in the noise generating said rough texture and furthermore, said surface scratches will break at the many seams.

Is the approach outlined in this series meant to showcase the use of the new UV unwrapping tools in R23 rather than illustrating a practical method of UV mapping a texture to this particular object?

Thanks again for your patience, consideration and knowledge!

- Brian

Hi Brian,

When you unwrap an object, you do it for a specific purpose. There is, as I tried to explain above, not the best way, AKA “one size fits all” approach. Nor is it always needed to begin with.

So, let’s investigate this case. A cast iron has either the noisy surface of a sand mold or is refined with machines. The rough mold aesthetic is the overall quality, and seams show up only where the mold was split. This split is typically used to take the hardwood dummy out and leave an empty space where the iron will flow into. This means we have a third surface quality somewhere: where the iron is flowing from the outside to the hollow space inside. This is the first area that will be worked on to achieve a tool part in this case. This can be done in many ways. It would be good to have that as a single island.

The simplest part here is the (negative) sandy surface. Which is normally done with a noise-shader in the bump, normal, or displacement channel. Typically, larger details will be done via displacement and smaller parts via bump, with the challenge to find a sweet-spot. Noise does not need any projection or UV if we talk about a 3D-shaders. Those need to know where a surface (including Phong) is and what value to provide.

The next area is the part where tools have been used to enable the functionality of this tool. Parts that move in a certain way to each other need to be smooth or even polished. (Visualizing cheap or pro-tools delivers the decision here). Complete, polished tools have no need for UV, they need a reflective surface, but scratches and dents need a projection or UV information.

If a grinding tool was used, it would vary in appearance. Here we might require UV if the tool was used continuously around the surface. Those need perhaps patches around UV seams, via projection or paint, stamping.

Another area is given for company logos and words or numbers that came with the mold or machined later into it. Those use a UV with certainty, but also here, a flat projection could do the trick. One might love to have the UV mesh baked into a layer, to be able to use Photoshop (or any other image app) to place those graphical or typo elements into place with ease. Setting up for each material and scale, rotate offset, or even tile seems more work and clutters the scene.

As a side note, the standard projections often help get what one needs, certainly in conjunction with polygon selections.

Again, BodyPaint3D is taking huge advantages from a proper UV, if not at all dependent on it.

In short, to just produce a UV without a plan might be wasted time. It is a translation of images. Those images would be a top view, side view, and so on, of a real object. Then the UV is adapted to it. While many qualities can’t be photographed (refraction or reflections), they need to be simulated with shaders or inside the material. The way an object is photographed to get the textures wanted sets the direction for the UVs.

To make all of that a little bit clearer, even I repeat myself here: If the UV would be an exact replicate of the model, what would be achieved? It would be 3D. It is a translation between 2D and 3D that makes its value, and there is the challenge. (Yes, there is UVW, but that is information for an algorithm, not for images/textures.)

Does this clear the use of UVs?

Cheers

Hello!

Thanks for breaking that down so thoroughly! Your patience and time is greatly appreciated.

Your explanation does help clear the air a bit more for me regarding UV’s and UV unwrapping.

It makes sense that you must have a plan in place to base your UV-related decisions upon.

If I am understanding it correctly, this plan could be dictated by factors related to the material properties of the object, such as the polished vs. rough portions of the pipe wrench we’ve been referencing.

Beyond the material, this plan may also be dictated by the physical properties of the model… are there portions of the model that would be a good location for a UV seam because they are covered by other portions of the model and cannot be seen by the camera.

Furthermore, this plan could be dictated by attributes of the scene itself… are there portions of the object that will not come into the camera’s view, making them great candidates for UV seams.

All in all, it makes total sense that there is no one-size-fits all approach and while there are still UV mapping concepts I cannot wrap my head around, I’m sure I’ll uncover their nuances in time.

I cannot thank you enough for you time and consideration!

- Brian

You’re very welcome, Brian.

One tip that I have given during hand-on classes in the past 16+ years is a pretty simple one:
For modeling, look at things around you; which tool or option would be the way to produce it (Lathe, Extrude, etc.)? This game can be played everywhere, especially when you have to wait somewhere for a moment or longer.

Like that is the idea to use the channels of a Standard-Material, and use it as a “shopping list”. In other words, what channel would provide the needed quality of the material we see in front of us?

Now back to UV, what is the strength and the weakness of it? We went already to a few areas here.  Think of three main areas, we don’t need any projection (the shader uses the object’s surface), we need standard projection (e.g., spherical, flat), and last but not least, anything that UV allows us to do. For example, UV allows overlapping UV polygons, so areas of a texture can be used many times with a particular area (Placing logos, and that with the same logo image with different sizes.)

All of that can be mixed, and with alpha channels or polygon selections, mixed partially. How would you cover an object with a stiff-paper while avoiding wrinkles?

Which can result in a similar game as with modeling and materials: Look around, e.g., in a super-market, what object would require what. This will create a particular kind of thinking that will lead to a more fluent way of working in Cinema 4D.

Extend later those out of the office games to lighting and animation and camera views. (Excuse me if I sound like I would know your skills, I don’t, but I write in a forum, and this is read by starters and pros alike. So I write more broadly.)

Allow yourself some time. No one, to my knowledge, knows everything, especially for all possible combinations in Cinema 4D. So, there will always be something to explore, to learn, or to invent!

Enjoy your exploration