If two separate groups of sample points share vertices, you can create a smooth transition between them by "healing" them together. Healing glues separate sample points back together by setting the shared points to their average UV values.
The Island Heal tool heals one or more source islands of a polygon object's UV coordinates to target boundaries that they share with another island. Before the boundaries are healed, either the source island or the target boundaries' island is translated and rotated such that the corresponding boundaries on both pieces are aligned. Then, the two islands are healed together along these boundaries.
This process is repeated for each source island (but source islands are not healed to each other, even if they share boundaries). Once the operation is complete, you can fine-tune the transformation, both to include scaling and to transform the target boundary's island if necessary.
You can choose a target boundary by selecting entire islands, or by selecting some of their points.
If you select the entire island, the source islands are healed to it along the entire length of their shared boundaries.
If you select points, the source islands are healed to whatever portion of the selection is a shared boundary.
You can choose target boundaries on multiple discontiguous islands, and each Island Heal operation can heal multiple source islands to the target boundaries.
Island heal is most useful when you've unfolded an object's UV coordinates using subprojections (see Creating Subprojections) because it allows you to quickly reconnect the various portions of the UV mesh without altering their proportions excessively.
Displaying connectivity tabs in the texture editor is an easy way to identify where discontiguous UV islands share boundaries before you heal them together. To display connectivity tabs, click the Show Connectivity button in the texture editor toolbar.
For more information about connectivity tabs, see Highlighting Connectivity.
Island Heal Workflow #1: Preselecting the Target Boundary
One way to use the Island Heal tool is to first select the target boundary and then apply the Island Heal. The advantage of this workflow is that the initial target boundary remains selected after the heal is applied. This allows you to heal several source islands to a single target, one after the other, without having to reselect the original target from the resulting island each time.
Collectively, this selection's boundaries are the target, to which the source island(s) will be healed.
From the texture editor command bar do one of the following:
Click the Island Heal to Picked button 
, or press Shift + . (period).
This will transform the target boundaries that you selected to align them with the corresponding boundaries on the source islands that you pick in the next step.
Click the Island Heal Picked button 
, or press Shift + , (comma).
This will transform the source islands that you pick in the next step to align them with the corresponding target boundaries that you already selected.
Pick multiple source islands using the rectangle-select tool.
The target boundaries/source islands are transformed according to the command you chose in step 2 and healed to the target boundary.
The Island Heal UVW Operator property editor opens.
Island Heal only considers boundaries shared between source islands and target boundaries, and it transforms the UV coordinates accordingly. In cases where you pick multiple source islands, some of which share boundaries with one another, those shared boundaries are not healed together.
In such cases, the source island UVs may end up overlapping in the healed result if the boundaries that they shared with the target island were close together. You can fix these overlaps using the standard Heal tool (see Healing Separated Points).
From the property editor, activate the Allow Scaling option if necessary.
This scales the source island to match the scale of the target boundaries, or vice versa, depending on the command you chose in step 2.
If necessary, adjust the Interpolate Source/Target value. Adjusting this value repositions the resulting island as if either the source island, the target boundary's island, or both were transformed before being healed together:
The default value of 1 positions the resulting island as if the source island was transformed to line up with the target boundary.
A value of 0 positions the resulting island as if the target boundary's island was transformed to line up with the source island.
In-between values interpolate between the two extremes, positioning the resulting island as if both the source island and target boundary's island were transformed. If you activated scaling in step 4, it is interpolated as well.
If necessary, repeat steps 2 to 5 for each additional source island that you wish to heal to the original target boundary.
Island Heal Workflow #2: Nothing is Selected
An alternative method of applying an Island Heal is to apply it first, pick the target boundary (or more accurately, target island), and then pick the source islands. This is sometimes a faster method when you want to heal whole boundaries together. Because nothing is selected, you don't have to worry about identifying the correct target boundary. The source islands are healed to the target boundaries wherever they correspond.
From the texture editor command bar do one of the following:
Click the Island Heal to Picked button , or press Shift + . (period).
This will transform the target islands that you pick in the next step to align them with the corresponding boundaries on the source islands that you pick in step 3.
Click the Island Heal Picked button, or press Shift + , (comma).
This will transform the source islands that you pick in step 3 to align them with the corresponding boundaries on the target islands that you pick in the next step.
Click or rectangle-select an island to set its boundary as the target boundary, to which the source islands will be healed.
Pick a source island to heal to the target island by clicking one of its points.
Pick multiple source islands using the rectangle-select tool.
From this point on, the process is identical to steps 4 and 5 of Island Heal Workflow #1: Preselecting the Target Boundary. However, because no target was explicitly selected, you cannot repeat the procedure to heal another island to the original target boundary.
or choose 
Heal
