Working with UVs in the UV Texture Editor
 
 
 

When texture mapping a polygon or subdivision surface type model it is often necessary to modify the UV components for a model so they match the texture map. The UV Texture Editor provides many tools for working with UVs. In this section you learn how to:

Selecting UV components

You can select UV components from either the scene view or within the UV Texture Editor. Displaying both the 3D scene view and the 2D view of the UV Texture Editor lets you easily correlate which UV components are associated with a particular edge or vertex on the 3D model.

This is very helpful to understand the layout and orientation of your UV texture coordinates in relation to the image used for a texture map and how the map appears on the model in the 3D scene view.

To select UVs for a 3D model in the scene view

  1. In the UV Texture Editor, select Image > Display Image to turn off the display of the texture image.

    Display Image works by turning the display of the assigned texture on or off in the 2D view of the UV Texture Editor. Turning the image off temporarily aids in viewing only the UV components. This will be useful in the steps that follow.

  2. In the scene view, right-click on the cracker box model and select UV from the marking menu that appears.
  3. In the scene view, select one UV on any corner of the cracker box.

    Selecting a UV is very similar to selecting a vertex on an object. That is, you select a point that resides in exactly the same position as the vertex. When you select a UV in the scene view, the corresponding UV is also selected in the UV Texture Editor.

    NoteIf more than one UV gets selected in the UV Texture Editor when you select a UV in the scene view it indicates that multiple UV components share the same UV on the 3D model (similar to how polygon faces share common vertices). This is important to remember when you move one of these UV components in the UV Texture Editor and other UVs also move.
  4. In the scene view, right-click on the cracker box model and select Edge from the marking menu that appears.
  5. In the perspective view, select the top front edge of the cracker box.

    When you select this edge in the scene view, notice that two corresponding shell edges also get selected in the UV Texture Editor. This indicates the following:

    • The selected edge is shared by two faces; the front and the top.
    • Selecting the top front edge in the scene view, identifies the corresponding front and top UV shells for the box. (Indicated by the selection in the UV Texture Editor.)

    This is useful when you need to understand how the various UV shells relate to each other, especially when you have many UV shells for a model in the scene; for example, when you sew two UV shell edges together.

In the steps that follow you select edges in the UV Texture Editor so you can sew them together.

Sewing UVs

Sewing UV shells together merges the UV shells along a shared edge that you specify. Sewing UVs is useful for the following reasons:

To sew shell edges together in the UV Texture Editor

  1. In the scene view, ensure that only the top front edge of the cracker box is still selected.

    When the top front edge is selected in the scene view, the top edge of one of the large UV shells is also selected as well as the left side of the middle UV shell in the top row of the UV Texture Editor. For the cracker box texture map, you need to sew these together so they correlate to the map correctly.

  2. In the UV Texture Editor, select Polygons > Move and Sew UV Edges.

    The small rectangular UV shell is repositioned to match the top of the large UV shell and the two shells are combined into one. When you later select and move this sewn shell, it will move as one piece. When two UV shells are selected for sewing, the smallest UV shell is moved to the larger.

  3. Repeat steps 1 and 2 for the remaining three edges on front face of the cracker box keeping in mind the following:
    • Select only one edge at a time in the scene view.
    • When you’ve completed the move and sew operation, your UV Texture Editor should show the front UV shell with the corresponding top, bottom, and side shells sewn to it. When fully complete, you will have only two UV shells to match to the texture image for the cracker box.

  4. To display the texture borders for the two shells, select Texture Border Edges. (You can also launch this window by right-clicking the Toggle Texture Borders button on the UV Texture Editor’s toolbar.)

    In the UV Texture Editor, the texture borders for two UV shells now appear with a thicker line.

Displaying texture borders on the UV shells is useful for visualizing where the texture borders exist on the 3D model in the scene view. That is, any portion of the texture image that appears outside of the texture border will not appear on the surface. It is particularly useful for troubleshooting texture mismatches when they occur. Displaying the texture borders can also help to identify which UV shells are combined and which shells are not when you have many UV shells displayed in the UV Texture Editor.

If you want to be able to view areas where UV shells overlap in the UV Texture Editor select Image > Shade UVs. When Shade UVs is turned on any selected UV shells appear shaded in a semitransparent fashion. Areas where the shading appears more opaque indicate the regions of shell overlap.

In the steps that follow, you reposition the two UV shells in the UV Texture Editor so they coincide with the texture image.

Moving UV components

You manually reposition UV components in the UV Texture Editor using the tools within the Toolbox. To reposition an individual UV component you must first select it before selecting the Move Tool. To reposition an entire UV shell you must first select one individual UV from the shell it belongs to and then convert the selection to a shell before using the Move Tool.

To move UVs in the UV Texture Editor

  1. In the UV Texture Editor, select Image > Display Image.

    The texture image displays in the 2D view of the UV Texture Editor dimmed, as before. You need the image displayed so you can accurately reposition the two UV shells. Dimming the image aids in seeing the selected UVs.

  2. In the UV Texture Editor, right-click and select UV from the marking menu that appears.
  3. In the UV Texture Editor, select one UV on the UV shell you sewed earlier in the lesson.

    The UV coordinate appears highlighted in the 2D view.

  4. Convert the selection to a UV shell by pressing the Ctrl key and right-clicking in the 2D view of the UV Texture Editor. Choose To Shell from the marking menu that appears.

    The selection changes from a single selected UV to selecting the entire UV shell.

  5. From the UV Texture Editor menu, select Tool > Move UV Shell Tool > .
  6. In the Move UV Shell Tool options window, turn off the Prevent overlap option which prevents UV shells from being moved so they overlap and then select Apply and Close.

    The Move Tool manipulator icon appears over the selected UV shell.

  7. Drag the green (Y axis) and red (X axis) Move Tool manipulator handles to reposition the UV shell so it matches the displayed texture image.

    The position of the texture updates on the cracker box model in the scene view as you do this.

  8. Select one UV on the other remaining UV shell.

    The UV coordinate appears highlighted.

  9. Convert the UV selection to a shell selection by pressing the Ctrl key and right-clicking in the UV Texture Editor. Choose To Shell from the marking menu that appears.

    The selection changes from a single selected UV to selecting the entire UV shell.

  10. In the UV Texture Editor’s toolbar, click one of the Rotate UVs buttons to rotate the UV shell so it appears in the same orientation as the texture image. (Click the other Rotate UVs button to rotate it in the opposite direction.)

  11. Confirm that the texture appears correctly on the cracker box model in the scene view by tumbling the scene so you can view the back of the box.
    TipIf the texture appears upside down, you can continue to rotate it another 180 degrees. If the texture appears reversed, that is, the letters are backwards, you can correct this by selecting Polygons > Flip from the UV Texture Editor menu and choosing the appropriate option setting.
  12. From the UV Texture Editor menu, select Tool > Move UV Shell Tool.

    A move manipulator icon appears over the selected UV shell.

  13. Drag the green (Y axis) and red (X axis) manipulator handles to reposition the UV shell so it matches the displayed texture image.

    The texture map should now appear correct on all sides of the cracker box when you’re finished.

    TipYou can confirm that the UV shells are positioned accurately by dollying in closer on the 2D view of the UV Texture Editor. If a minor correction is required, simply select and move the UVs or move the entire UV shell.

    TipThe exact UV boundaries can be viewed more clearly when the anti-aliasing for the texture image is temporarily turned off. To do this, select Image > Display Unfiltered to view the texture image without anti-aliasing.

    If you need to move a single UV so it precisely matches a particular location on the texture map you can turn on Pixel Snap (Image > Pixel Snap). When you select and move the UV using the Move Tool, it will reposition the UV coordinate based on pixel boundaries.