Materials, Part 3. UV Mappers. Section One: Getting Started
(version September 16, 2007)
This is a large and detailed topic. We will discuss it in stages slowly over time. The first Section (Section One) introduces the topic and gets you acquainted with the basics, introducing the terminology for later sections. We discuss some freebies and some paid standalone tools. But some 3D software in the 3D Animation Lab already has built into it the necessary UV Mapping tools. We'll talk about all of these and show you how you can become an expert modeler and animator by learning how to make these tools work for you.
The subject of UV Mappers is somewhat large. The topic is divided into multiple sections.
Section One: Getting Started. - The initial discussion, some definitions and examples. Using an unwrapperSection Two: A Little Deeper - Using a unwrapper, explaining unfolding.
Section Three: Using an unwrapper with a Poser figure
Section Four: A Look at unwrapping in trueSpace
The main goal of this topic is to help you customize a model so that it looks just right for your purposes. This information is useful if you are loading a model from someone else or if you are finishing one of your models. Occasionally you need to make changes to the texture of a model because the demands of an animation require something additional. This information will be useful to you throughout your 3D career.
Should I Be Afraid of UV Mappers?
Not at all. It may look like a difficult topic, yet it is not. It is large, however, and we will take bite-size chunks of the topic here, and play with them. You will be able to follow along as well. There are some tools for free on the Web which you can use to work with at home. The 3D Animation Lab has other software, some with built-in handling of UV Mapping. In any case, you will have a chance to learn if you follow along. We think you will have some fun as well. We will consider the UV Mapping functions in trueSpace and use them to illustrate the work we do here. We will take a look at texture maps in Poser for the human form and try to understand what we see there. In short order you will be on your way to creating your own UV Maps and making sophisticated textures that do what you want them to do.
Mapping Magician is a good freebie to follow along with. The Web site has some tutorials and offers other perspectives on this topic. Those tutorials go well beyond what we are including here in Section One: Getting Started. You might hold off reading them all the way through until you have finished this article, but that is your choice. This article on the 3D Animation Lab Web site will have additional sections over time, and we invite you to come back to read the new installments.
The Kleenex Tissue Box and the Globe
It can be some other brand (not Kleenex), the shape is really what we are interested in. The globe is more interesting, but we will save that until we understand tissue boxes. We assume that the tissue box has been opened (hole removed from the top and sides so that you can get at the tissues). We are take the box apart. If you do this well, you will be able to put it back together and no one will know. (Make sure Mom is not looking.) Grab the tissue box, remove its contents, and place the tissues where the box was. The tissue are not missing, just the box is. Members of your household might forgive you, especially if you spend time explaining to them what a UV Map is. Or they might just throw the stack of tissues at you and storm out of the room.
Carefully take the tissue box apart. Don't use scissors, just pull carefully. Find all the seams and run your fingers through them to separate the sections. Some tearing is okay if you have Scotch tape. At the end of your tearing the box apart, you will have a flat, sheet of cardboard printed on one side. If you were sloppy in separating the seams, remove any excess paper using your fingers. Look at the printed side. Your box will look somewhat like this one. The exact details are not important right at the moment. Notice in particular the two side tabs on the right and left that say "Puffs". The printing is not done by taking a normal image and applying it to a sheet of cardboard. Each side of the box has its own orientation for how the printing is done. When we do a UV Mapping of a cube we will do much the same thing. We can then assign a texture or picture to each flap of our cube when the skin or surface is flattened out. When the edges are put back in their original position to make a cube, we will have the printing we want on each side in the orientation we want. We'll do some more examples for this concept to become clear.
Not everything in the world is a box or a cube. We have spherical objects as well. Let's take a look a what happens to a sphere such as a globe.
Here is a sample screen from Ultimate Unwrap, one of the paid UV Mapping tools that we like a lot. Click on the Link to view their Web page, which is very informative. On the screen below we have a sphere (not perfectly smooth but instead with 16 segments around the latitude (= equator) so that the UV Map will be easier to understand). Right below this image is another of just the left side of the screen so that you can see an enlargement of the UV Map.
The sphere is broken in 16 vertical segments and each vertical segment has 8 parts. We'll take another look at this to make it very clear what we mean. Try to see the 16 vertical segments on the sphere (some are hidden in back, aren't they?--but they are still there). And for each vertical segment can you count 8 parts? The illustration shown below makes it easier. Take a look at it then come back to these two pictures and do the same check for 16 vertical segments, each with 8 parts. The diagram directly below shows how each segment of the sphere gets mapped to something in the flat image to the lower left.
Map makers have been doing this kind of thing with the globe for hundreds of years, looking for the best "Projection" of a sphere onto a flat surface. If you are a maker of globes, you start of with printing on a sheet of cardboard which looks very much like the diagram in the lower left. In general a quality map maker may use many more segments than 16. The printing is done on a flat sheet which is cut to include only those pieces that get reassembled into a globe.
So far our discussion has been along the lines of visualizing UV mapping and seeing what an unwrapper does. We will do a few more experiments to get this concept down very clear.
Practical Exercises Using Ultimate Unwrap
UV mapping and unwrapping come about to handle some practical problems that 3D artists and animators have always faced. The biggest problem is that we live in a 3D world but most of our tools are 2D. My computer screen is 2D, and most likely so is yours. If not, you are very lucky indeed. Printing presses which print on the cardboard that is wrapped into a globe are also 2D. 3D printing presses are not here yet, are they? Since our toolset is stuck in a 2D world (mouse, screen, printing, and more), we need ways to make that work in our 3D world. Luckily we have UV Mapping.
We are going to make a photo cube. This is a 6-sided lucite cube that many people have on their desks with pictures of friends and family. You have probably seen such a cube. Let's do the same thing in software. We'll use Ultimate Unwrap and Photoshop. The procedure will be like this. 1. Create the cube in Ultimate Unwrap and unwrap it. 2. Export the unwrapped cube. 3. Load into Photoshop and edit. Save. 4. Re-import back into Ultimate Unwrap and view the result.
We begin by telling Ultimate Unwrap to create a Box (Create | Box) where each side is made up of one segment for a total of 6 segments. We leave the sides all the same size.
As you click into each cube in the unwrapped map, the corresponding face on the cube lights up (some are hidden, but you can rotate the cube to see them). On the left of the panel below we clicked into the top right and the on the right of the panel the front face of the cube became highlighted in red.
Here is our exported UV map before we make any changes. We exported in PSD format.
We will put an image on each of the white squares. Here is our result.
This image now gets re-imported into Ultimate Unwrap. Some steps are needed to load this bitmap and assign it to the faces. Once we do these steps, however, the result is what we expected.
The pictures have now been applied to our cube on all faces. If we turn and rotate the cube to view all sides we will see all six pictures.
For now that concludes the first Section of using UV Mapping software. We still need to define what UV stands for and go much deeper.
Additional articles will appear in this section.
Topics for further exploration and reading on your own
1. Find some Kleenex or Puffs (still in the box) and do the experiment above. If you have Scotch tape on hand almost no one will be the wiser, unless you tell them.
2. Take a look at the Web sit for Ultimate Unwrap and follow through some of the tutorials. Try out the Ultimate Unwrap demo which is fully functional, non-expiring except it does not save files. You will be able to do some following along with the tutorials and you will be able to repeat the examples shown here.
3. How many total segments are there in our first example of the globe above? HINT: Count them using the unwrapped image of the globe.
4. Tell a friend what you learned by reading this article. Show him or her some examples. You will increase your understanding of the topics presented here when you present them to someone else.
We enjoy hearing from you. Some of the questions listed above will appear in future "Topics in 3D" articles. Please send your comments about this article to 
