If you want to apply the same texture across several objects, group them first by selecting them and clicking the Group button in the Edit panel.
The easiest way to apply a texture projection is to do it “on the fly” (as described in Three Basic Texturing Methods) because you are prompted to define the projection as you apply the texture. However, you can apply texture projections before you apply textures and connect the texture images to the projections later.
1. Select an object, several objects, a group, or a hierarchy.
2. Choose Get > Property > Texture Projection > projection type from any toolbar. The projection is applied to the object(s).
When you apply a texture to your object this way, you can then apply a texture to the object and connect it to the projection that you just created.
A simple and convenient way to texture objects is to project a texture from the camera onto the object’s surface, much like a slide projector does. Once you manipulate the texture on the surface to your liking, you can freeze the projection.
To project a texture using the camera
1. Select the object or objects to texture.
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If you want to apply the same texture across several objects, group them first by selecting them and clicking the Group button in the Edit panel. |
2. Apply a texture using any of the methods described in Applying Textures.
3. From the Texture tab, click New (under Texture Projection) and choose Camera Projection.
4. Once you select Camera Projection, you must select a camera from either the explorer or a 3D view. The selected camera then projects the texture.
Now the texture will be recomputed every time the camera moves.
5. Open a render region in a camera view and orbit, pan, or transform the object until you position the texture as desired.
Once you apply the texture’s projection to your liking, or you want to stop the texture from following the camera, you can freeze the projection. For more information about freezing texture projections, see Muting and Freezing Texture Projections.
Cubic texture projections, though similar to other texture projections, often require a bit more configuration because each face of the cube is individually configurable. When you apply a cubic projection to an object, each of the objects polygons is assigned to a face of the cube. The texture image (or part of it) is then projected onto each face.
When you apply a cubic projection, you can specify how the object’s polygons are assigned to faces, and transform each face so that the texture is properly positioned.
To apply a cubic texture projection
1. Select one or more objects to texture.
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If you want to apply the same texture across several objects, group them first by selecting them and clicking the Group button in the Edit panel. |
2. Apply a texture using any of the methods described in Applying Textures.
3. From the Texture tab, click New (under Texture Projection) and choose Cubic.
4. Click the Edit button on the Texture tab (beside the Texture Projection list) to open the Texture Projection property editor.
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You may want to click the lock button in the property editor’s title bar. This ensures that the property editor stays open and remains focused on the texture projection in the following steps. |
5. If you wish to apply a cubic projection preset to the object, go to the Layout tab and do one of the following:
- Click one of the Preset icons.
or
- Click the Load Preset button under the Preset options, select a preset from the browser and click OK.
For more information about cubic projection presets, see Saving and Loading Cubic Projection Presets.
6. From the Layout tab of the Texture Support page, choose a Face Selection Method:
- Using Normals assigns each polygon to a face of the cubic projection based on the orientation of the polygon’s normal.
- Using Positions looks at all of a polygons points and determines which face of the cubic projection each point is closest to. If all of the points are closest to a single face, then the polygon is assigned to that face. Otherwise, a heuristic based on point positions and polygon normal orientation is used to resolve ambiguities and decide on a face for the polygon.
When the face selection method is set to Using Normals, you may get inconsistent results on complex geometry. If it’s important that the projection layout be more consistent, the Using Positions method may be more appropriate. This is illustrated in the following example:
7. If necessary, choose a Face Projection method for all faces of the cubic projection:
- All Planar places a planar projection of the texture image on each face of the cube. Each face’s projection is consistent with its orientation.
- All Spherical places a spherical projection of the texture image on each face of the cube using the center of the texture support’s bounding box.
The spherical Face Projection method is useful when you are applying a cubic texture projection to a more or less spherical object. It helps to minimize the distortion that usually occurs when you apply a planar texture projection to a curved surface, as shown in the following example:
You can also assign a projection method to each face individually as described in the next step.
8. From the Custom tab of the Texture Support page, you can transform each face’s UV coordinates individually.
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• Besides allowing you to position the texture properly, adjusting the faces of the cube allows you to easily allocate more or less of the texture image to a given face. For example, if you apply a cubic projection to a model of a head, you can allocate more of the texture to the face, and less of the texture to less detailed areas. • To see the result of the transformations on the projection’s UV coordinates, open the texture editor (press Alt+7) while editing the transformation values. |
9. You can now save the transformed projection as a cubic projection preset, as described in the following section.
Saving and Loading Cubic Projection Presets
By default, a cubic projection projects the entire texture image onto each face of the cube. However, you can quickly change the projection’s UV coordinates by loading a cubic projection preset likes the ones shown in the following image.
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These cubic projection presets are designed to be used with texture images that conform more or less to their shape, rather than with square texture images like the one shown above. For example, the Linear preset is designed for a long rectangular texture. |
You can also modify a cubic projection manually and save it as a new preset.
To save a cubic projection preset
1. Select an object and apply a cubic texture projection to it as described in Applying a Cubic Projection.
2. From the texture projection’s property editor, adjust the projection’s UV coordinates using the controls on the Custom tab of the Texture Support page.
3. From the Layout tab of the Texture Support page, click the Save Preset button and, from the browser, choose a directory and file name for your preset.
4. Click OK.
To load a cubic projection preset
1. Select and apply a cubic texture projection to it as described in Applying a Cubic Projection.
2. Select the object’s cubic texture support and press Enter to open the Texture Support property editor.
3. From the Layout tab of the Texture Support page, do one of the following:
- Click one of the Preset icons.
or
- Click the Load Preset button and choose a cubic projection preset (Cubic_verticalcross.Preset for example) from the browser.
The preset is applied to the object.
Unfolding a Texture Projection
Unfolding creates a UV texture projection by “unwrapping” a polygon mesh object using the edges you specify as cut lines or seams. When unfolding, the cut lines are treated as if they are disconnected to create borders or separate islands in the texture projection. The result is like peeling an orange or a banana and laying the skin out flat.
To unfold a polygon mesh object
1. Select a polygon mesh object.
If desired, you can also select edges to use as cut lines (remember to click Add to Cut Line in step 3). Whether you or not you select edges now, you can still add and remove cut lines later in the procedure.
2. Choose Get > Property > Texture Projection > Unfold. This command is available from the Model, Animate, Render, and Simulate toolbars.
An Unfold property is applied to the mesh and its property editor opens. For a description of all the options in this property editor, see Unfold Property Editor [Properties Reference].
3. Define the edges to use as cut lines:
- Select some edges and click Add to Cut Line. Repeat to add more edges.
- If you added some edges that you don’t want, select them and click Remove from Cut Line.
- To start over with a completely new set of edges, select the desired edges and click Set from Current Edges.
- To see the edges that are currently set as cut lines at any time, click Select Cut Line.
4. When you have set the desired cut lines, click Unfold.
5. Open the texture editor (Alt+7) or refresh it to see the result of the unfolding. Note that if the object already had a UV texture projection, then you may need to select the Unfold projection from the UVs menu.
6. If desired, you can continue to adjust the cut lines as in step 3. Click Update Unfold to see the results in the texture editor.
7. Use the Texture Editor - Adjust Unfold options to reduce the amount of surface stretching (at the expense of distorting the edge angles). You can either set these options and then click Adjust, or activate Live adjusting to see the effects as you make changes.
8. Use the options on the Packing tab to control how the UV islands are laid out in UV space. You can either set these options and then click Pack, or activate Live packing to see the effects as you make changes.
9. If you need to make changes later, you can re-open the Unfold property from an explorer:
You can also make manual changes in the texture editor, but they will be lost if you update the unfolding.
If you are completely satisfied with the unfolding and certain that you will never need to change it, you can also freeze the texture projection.
The Freeze M button (freeze modeling) does not freeze the Unfold operator in the texture projection stack. To freeze it, do either of the following:
• Select the Unfold operator in an explorer and click Freeze. For more information, see Muting and Freezing Texture Projections.
or
• In the texture editor, choose Edit > Freeze.
Freezing the Unfold operator does not remove the Unfold custom property on the object. If the operator has been frozen, then clicking Update Unfold will create a new set of UV coordinates.
Applying a Contour Stretch UVs Projection
Contour Stretch UVs projections are useful for a number of different texturing tasks, particularly for applying textures to tracks, and irregular terrain-like meshes. They are also useful for fitting regular-shaped textures onto curved meshes. For example, they would be useful to place a label texture on a beer bottle, right at the junction of the bottle’s neck and body.
Although the easiest geometry to contour stretch is a perfect quad, it’s more likely that you’ll want to use contour stretch projections on less regular shapes. This is not a problem as long as you keep a few simple guidelines in mind when you make your selection.
• The selection cannot be a whole object: it must be a selection of polygons with an identifiable contour.
• Although the selection doesn’t have to be perfectly rectangular, the contour stretch projection must be able to derive four corners from its contour.
• If the selection has holes in it, it is more likely to produce undesirable results.
• If the selection consists of two or more discontiguous “islands,” their UV coordinates do not remain separated in the texture editor once the projection is applied. Instead, they are treated as a single, one-piece selection.
To apply a Contour Stretch UVs projection to a polygon selection
1. Select any number polygons on the object to which you want to apply the contour stretch projection.
Remember that the selection must have four discernible corners (even if it isn’t perfectly rectangular) and a clear contour.
2. From the Render toolbar, choose Get > Property > Texture Projection > Contour Stretch UVs.
The selection’s corners are automatically detected, the object’s points are displayed, and a pick session begins.
3. Do one of the following:
- If necessary, pick new corners for the polygon selection to which you are applying the projection. The new corners must lie on the boundary of the initial polygon selection. Then right-click to end the pick session.
or
- Right-click to end the pick session and use the automatically detected corners.
Three things happen:
- An internal cluster, which is neither visible nor selectable, is created from the initial polygon selection.
- The contour stretch projection is applied to the cluster.
- The PolyUVContourStretching property editor opens.
4. Apply a texture to the object using any of the methods described [here]. Make sure that you use the contour stretch projection.
5. Choose a contour stretch method for the projection as described in Choosing a Contour Stretch Method.
6. If necessary, adjust the Interior Smooth option to smooth internal points of the UV coordinate set (the contour is unaffected). The effect is to spread the UV coordinates outward within their contour.
This setting is especially useful when the initial Contour Stretch projection has created undesired overlapping of UV coordinates.
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Unlike the texture editor’s Relax operation (see [here]), which attempts to smooth the UV coordinates by linking tension in 2D and 3D space, Interior Smooth computations are done only in the UV domain. |
7. Do the following in any order:
- If necessary, adjust the projection’s contour as described in Controlling a Contour Stretch Projection’s Contour.
- If necessary, adjust the projection’s UV coordinates as described in Adjusting a Contour Stretch Projection’s UV Coordinates.
You may find it easier to adjust the projection’s UV coordinates before you adjust its contour. The UV coordinate adjustments allow you to roughly position and orient the UV coordinates on the texture. You can then refine the projection using the Contour Controls settings.
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Once you’ve applied a contour stretch projection, modifying any of the topology changes that you made before applying it will have dramatic and usually undesirable results. This is because the topology change affects the contour that the projection uses to stretch the polygon selection. |
Choosing a Contour Stretch Method
Choosing the correct contour stretch method is an important part of applying a contour stretch projection. The method you choose should be the one best suited to the contour your polygon selection. The following methods are available:
• Walking on the Mesh from Contours calculates the UV coordinates by following the mesh as closely as possible from contour to contour, in both the U and V directions, and accumulating edge distances from the selection’s borders. This option usually gives the best results, particularly on complex meshes.
• Spatial Distance from Contours calculates the UV coordinates by travelling from border to border without trying to follow the mesh. This method works well on meshes that are relatively flat, and whose contours are more or less parallel. It also tends to be faster to calculate than other methods, especially on simple meshes.
• Walking NxM Regular Quads from Contours calculates the UV coordinates by “walking” from border to border and trying to build parallel border lines to produce a grid-like structure. This method is most effective for uniform-density meshes of NxM rectangular quads. It may produce undesirable results when the mesh is irregularly shaped.
• Projection on Surface Built from Contours creates an internal parametric surface using the contours and borders of the polygon selection and then projects the polygon selection onto that surface to calculate its texture coordinates. This method is especially useful for bumpy, terrain-like surfaces.
To choose a contour stretch method
1. Apply a contour stretch projection to a selection of an object’s polygons as described in the previous section.
2. If the PolyUVContourStretching property editor is not still open, locate the PolyUVContourStretching operator in the explorer and click its icon to open the property editor.
3. Choose a stretching Method for the projection:
Controlling a Contour Stretch Projection’s Contour
When you apply a contour stretch projection, you may find that the 2D representation of the polygon selection’s contour does not match the actually 3D contour as closely as you’s like. The settings in the Contour Control section of the PolyUVContourStretching property editor allow you to adjust the 2D contour of the UV coordinates so that it more closely resembles it 3D counterpart. The following settings are available:
• Tension pulls the contour inwards towards the internal 2D representation of the 3D contour. When you apply a contour stretch projection, the UV coordinates typically occupy the entire UV domain in at least one direction, creating a square or rectangular UV set. Adjusting the tension creates a better correspondence between the 2D and 3D representations of the contour.
Tension is the master control for adjusting the contour. Once you’ve begun to adjust the tension, you can refine the adjustment using the Contour Smooth and Deviation settings. If the Tension value is set to 0, these parameters have no effect on the contour.
• Contour Smooth smooths the contour of the UV coordinate set so that it better matches the original contour of the selection in 3D space.
This can help to smooth out areas of the UV coordinates that have been overly affected by changes to the Tension setting. UV coordinates within the contour are not smoothed, but may be displaced based on changes to the contour.
• Deviation controls the local deviation of the projection plane at each point on the 3D contour.
A local projection plane is calculated for each contour point, and the Deviation value controls the “rotation” of that plane. This helps compensate for variations in the orientation of the 3D geometry that aren’t accurately reflected in the 2D UV coordinate representation.
For example, if you apply a contour stretch projection to the polygons on the forehead of a head model, the contour points closer to the top of the head are oriented differently than those closer to the face. Since a single plane of projection is not appropriate for all of these points, adjusting the Deviation will adjust the plane of projection at each point, creating a more accurate UV representation of the forehead.
To adjust the projection’s contour
1. Apply a contour stretch projection to a selection of an object’s polygons as described [here].
2. If the PolyUVContourStretching property editor is not still open, locate the PolyUVContourStretching operator in the explorer and click its icon to open the property editor.
3. From the Contour Controls section, set the Tension value to something other than 0. This activates the other Contour control parameters.
4. You can now adjust the Contour Smooth and Deviation settings as needed.
Since each of the Contour Control settings tend to alter the effects of the others somewhat, you should continue to adjust all three until you’re satisfied with the shape of the contour.
5. If necessary, activate Clamp to pin the four corners of the UV coordinate set to the four corners of the UV domain.
The corner points remain fixed in position even if other Contour Control settings pull the rest of the contour inward.
Adjusting a Contour Stretch Projection’s UV Coordinates
When you apply a contour stretch projection, the polygon selection’s UV coordinates may not end up exactly where you want them on the texture image. The parameters in the Corner UV Values section of the PolyUVContourStretching property editor allow you to quickly adjust the UV coordinates’ position and orientation.
1. Apply a contour stretch projection to a selection of an object’s polygons as described [here].
2. If the PolyUVContourStretching property editor is not still open, locate the PolyUVContourStretching operator in the explorer and click its icon to open the property editor.
3. From the Corner UV Values section, adjust the Shift Corner value to shift the position of the projection’s start corner on the texture image. This rotates the projection’s UV coordinates in a clockwise direction as the value increases.
4. If necessary, activate the SwapUV option to exchange the U and V directions of the texture coordinates. The texture is flipped and rotated.
5. If necessary, select the MaintainAspect option so that the projection’s UV coordinates on the texture image preserves, as much as possible, the aspect ratio of the polygon selection on the object.
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The aspect ratio of the polygon selection is calculated based on the U and V lengths of its contours, not the dimensions of the area that it occupies nor its bounding box. |
6. If necessary, use the U/V Min/Max settings to control the position of the projection’s UV coordinates on the texture image. Min and Max values correspond to start and end positions in the U and V directions.
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