Object Unwrapping

In this tutorial we will describe how to unwrap an object onto a single texture. The created texture can then be painted using a Paint program.

This tutorial assumes familiarity with 3D Canvas and that the 3D Canvas Basics and the Oriented Modelling tutorials have been completed.

The Unwrap Operation is part of 3D Canvas Plus/Pro.

If you have a pre-prepared texture that you want to apply to an object see the Material and UV Map operations.

bulletDrag and drop a cylinder onto the scene.

 

 
bulletSelect the Point and Face Selection tool from the Edit Toolbar. The Edit toolbar is located along the right side of the 3D Canvas Window.

Click on the main toolbar to change to Face Coordinates mode.

Click on the main toolbar to select Operation Direction highlighting.

The Unwrap operation can either create a new texture, or add unwrapping information to an existing texture. If there is an active texture on the Material Palette 3D Canvas will add to that texture. Since we want to create a new texture, click on the material palette to clear the current material. This also selects Flat wrapping, which is often the most effective texture application technique for the Unwrap operation.

Select the top face of the object as shown. Notice that the direction map shows no distortion. That means that when we apply a texture, or in this case Unwrap, there will not be any distortion. This is a function of being in Face Coordinates mode. See the Oriented Modelling tutorial for more information.
 

 
bulletClick the Unwrap operation.

This will open the Unwrap operation window.

The white area in the right pane is the newly created texture. The circle is the top of the cylinder unwrapped onto the new texture. Each of the points of the cylinder top is represented by a green texture coordinate handle. These can be moved individually if need be, but in this tutorial we will re-size and move them as a group.
 

 
bulletClick to reduce the mapping size as shown. Ctrl-clicking reduces the mapping size by a small amount.

Then use the arrow buttons to move the mapping as shown. Take care not to move beyond the edges of the texture area (shown in white). If you do, click to reset to the initial unwrap size and position. Once you get near the edges ctrl-click the arrow buttons to move a small amount.

Notice that a checker pattern is applied to the object. This is done to assist you in achieving continuity and in reducing distortion. Continuity can often be improved and distortion reduced by manually moving texture coordinate points. With this simple object there is no need to do this since it is done automatically.
 

 
bulletClick OK. You will be asked to save your newly created texture.

Notice that the checker pattern is applied in 3D Canvas and that the Material Palette has been updated to show your newly created texture.

If you want, you could apply the new texture to the object by clicking on the Operations Layers list. In this tutorial we will not. We will wait until the final step so that we can retain the continuity mapping through the entire procedure.

 
bulletSelect the bottom face of the cylinder.

Again, the Face Coordinates mode ensures that we get no distortion.

 
bulletClick the Unwrap operation.

Notice that the new unwrap was added to the previously created texture since the texture was active in the Material Palette.
 
bulletReduce the mapping size and move it as shown. Click OK.

 
bulletAgain a checker pattern is applied so that you can track continuity and distortion.

 
bulletSelect half of the side faces of the cylinder as shown.

Notice that the direction map shows problems with distortion. The orange checks are considerably different in shape than the other checks. We could unwrap using this selection, but the results would be difficult to use later in a paint program.

 
bulletSelect a smaller section of faces. In this example one quarter of the side faces were selected. This shows very little distortion. All checks are roughly the same shape and size. Note they do not have to be square. Just the same shape and size.

With complex objects it is not possible to achieve checks of equal size and shape. That is where manual adjustment of texture coordinates becomes important. In this tutorial we are restricting ourselves to a simple shape in order to show the basics of object unwrapping.
 

 
bulletClick the Unwrap operation.

Size and move the unwrapped area to an unused location as shown.

Ideally, the checks should be square and equal in size. In this case they are not square. Fortunately we can adjust both the size and the shape using the reduce and enlarge functions.

 
bulletShift-click to vertically enlarge the size of the unwrap until the checks in the preview window are square.

Position the unwrap as shown.

You will notice that the size of the checks on the sides of the cylinder are larger than the size of the checks on the top of the cylinder. In this example it is not important that the texture for the top is of the same scale as the sides. If this were a requirement, we could correct it by erasing the improperly unwrapped sections of our texture using Microsoft Paint or another image editing program and re-unwrapping the out of scale sections.

 

 
bulletContinue unwrapping the side faces of the cylinder.

Ensure that the checks remain square and are the same size as the checks of the previously unwrapped side faces.

Notice that at this point our continuity mapping does not exactly line up. This is not necessary as long as the general direction of the continuity mapping is correct. However, if they do line up, it can be easier to paint the texture since brush strokes can be continuous if the unwrap is continuous. Shifting the newly unwrapped section to the left will result in a continuous mapping.
 

 
bulletHere is our unwrapped object with continuity mapping applied.

Note that the checks are square across the whole cylinder. That means there is very little distortion. But, the top and bottom are of a different scale than the sides. Normally we would want checks to be equal in size across the entire object. But in cases such as this where continuity between the sides and top is not critical this can actually be useful since you can dedicate more texture pixels to one region than another.

 
bulletRight-click on a face and choose "Select->All->Faces"

Here is an example of a poor direction map. Face Coordinates mode works best when a relatively small percentage of an object's faces are selected.

 
bulletWith all faces still selected choose Use Plug-in->UpdateMaterial from the Tools menu.

We now have an unwrapped cylinder with the unwrapped texture applied.

You can now use a paint program such as Microsoft Paint to paint on your unwrapped texture.

While you are painting your texture you can have 3D Canvas open as well. Every time that you want to see how your painting looks, just select the most recently used document from the 3D Canvas File menu. This will reload the model and show the updated texture.

This particular example was quite simple. Unwrapping a complicated object such as a model of a human is considerably more difficult. If you find that you are having difficulty removing distortion, you can manually move texture coordinate points to reduce distortion and improve continuity. But regardless of the amount of manual intervention, there will always be some distortion and continuity problems with complicated objects since we are mapping a 3D object onto a 2D surface. In cases where a choice has to be made between reduced distortion and improved continuity it is usually best to favour improved continuity. This permits easier painting of the texture.
 

 
bulletYou may have noticed that we have extra unused space on our unwrapped texture. Using the unwrap operation requires that some estimation be done to ensure that the entire texture is used.

A good technique to ensure that little rework is required is to intentionally leave space on the texture. In this example we intentionally left blank space just in case we miscalculated on how much texture space would be needed. We worked from the top left corner to the right bottom corner in an attempt to create an area that is easy to crop with a Paint program.
 
bulletHere we have cropped the texture to remove blank space. Note that we have to retain a square texture, so not all blank space could be removed.

 
bulletThe effect of this cropping resulted in incorrect texture wrapping. This is simple to correct with the UV Re-Map operation.

 
bulletTo correct this, simply select the object and click the UV ReMap operation.

Now it is just a matter of moving and resizing the remap to overlap the previously unwrapped texture.

 
bulletThe texture is now properly remapped.

This procedure also works if you have run out of space on your unwrapped texture. But in that case it is necessary to apply the texture in a incomplete state, resize the texture, use the UV ReMap operation, and then unwrap the remainder of the object.