You can also apply planar subprojections when working in the texture editor. For more information about subprojections, see Creating Subprojections.
Choosing the right type of texture projection is an important part of the texturing process. The more closely the projection conforms to the original shape of the object, the less you’ll have to adjust the texture to get the object looking just right. This section describes the types of texture projection that are available to you.
Subprojections
Once you’ve applied a texture using a given projection, you’ll probably have to fine-tune it by editing its UV coordinates in the texture editor. Several of the projection types discussed in the following sections are also available as subprojections. Subprojections allow you to reproject the texture image onto a selection of a polygon object’s components (polygons, points, and so on) using a different projection method.
For more information about subprojections, see Creating Subprojections.
For XY, XZ, and YZ mapping, imagine an image being projected onto a cube. If the picture file is mapped onto XY coordinates, its pixels are then projected accurately onto the XY surface plane of the object. The projection plane is (by default) one pixel smaller than the surface plane, therefore no “streaking” or distortion occurs on the object’s other planes.
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You can also apply planar subprojections when working in the texture editor. For more information about subprojections, see Creating Subprojections. |
If you map the picture file cylindrically, it is projected as if wrapped around a cylinder.
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You can also apply cylindrical subprojections when working in the texture editor. For more information about subprojections, see Creating Subprojections. |
When mapped spherically, the picture file surrounds the object and covers the entire surface with some distortion. A standard spherical projection stretches the texture over the front of the object so that its edges meet at the back. Distortion occurs towards the pinch points at the object’s +Y and -Y poles.
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You can also apply spherical subprojections when working in the texture editor. For more information about subprojections, see Creating Subprojections. |
A lollipop projection is a spherical-type texture projection where the texture’s corners stretch over the top of the object and meet on the bottom, like the wrapper of a lollipop. A single pinch-point occurs at the -Y pole.
UV mapping is the most versatile mapping method that you can use on NURBS surface objects as well as polygon meshes. It behaves like a rubber skin stretched over the object’s surface. The points of the object correspond exactly to a particular coordinate in the texture, allowing you to accurately map a texture to the object’s geometry. Even when you deform an object, its texture follows the object’s geometry.
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Reparameterizing a UV surface will reparameterize the UV projection as well. |
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. This is useful for projecting live action backgrounds into your scene so you can model and animate your 3D elements against them.
Changing the camera’s position changes the projection’s position. Once you have positioned the texture on the surface to your liking, you can freeze the projection (see [here]).
For more information about applying camera projections, see Applying a Camera Projection.
When you apply a cubic projection to an object, the object’s polygons are assigned to a specific face of the cube based either on the orientation of their polygon normals, or their positions relative to the cubic texture support. The texture is then projected onto each face using a planar or spherical projection method.
By default, the entire texture is projected onto each face. However, you can choose from a number of different cubic projection presets. You can also transform each face of the cube individually and save the transformations as presets of your own.
For more information about applying and adjusting cubic projections, see Applying a Cubic Projection.
For more information about cubic projection presets, see Saving and Loading Cubic Projection Presets.
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You can also apply cubic subprojections when working in the texture editor. For more information about subprojections, see Creating Subprojections. |
A spatial projection is a three-dimensional UVW texture projection that has either the object’s origin or the scene’s origin as its center. Spatial texture projections have their own texture supports. By default, the support appears in the center of the object’s volume.
You can transform the support, as you would any other texture support, to manipulate the texture. You can also modify the projection on the support using the Modify Projection tool, which is described in Modifying Texture Projections.
For more information about working with texture supports, see Using the Texture Support Object.
Computing Spatial Projections in Object Space vs. World Space
A spatial projection is the type of projection to use if you wish to have your object(s) “swimming” in a procedural texture, meaning that the texture changes as the object is transformed.
• By default, the projection is computed in object (local) space. The swimming effect is apparent when the object’s geometry changes.
• If you delete the texture support object, the projection is computed in world (global) space. The swimming effect is apparent when any transformation is applied to the object.
• If you would like to stop the swimming effect entirely, you can freeze the projection as described [here].
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When you import scenes from previous versions of Autodesk Softimage, you’ll notice that spatial projections have no texture support. In such cases, you can still have the projection computed in world space by doing the following: 1. Select the object and open an explorer. 2. Locate the GeoTxtOp operator (under the object’s Texture Projection node) and click its icon to open its property editor. 3. Activate the Compute in World Space option. |
Unique UVs Projection (Polygons Only)
Unique UVs mapping applies a texture to polygon objects using one of two possible methods:
• Individual polygon packing assigns each polygon’s UV coordinates to its own distinct piece of the texture so that no one polygon’s coordinates overlap another’s.
This is useful for rendermapping polygon objects. Typically, you apply textures to an object using a projection type appropriate to its geometry. Then you can rendermap the object using a new Unique UVs projection to output a texture image that you can reapply to the object. The texture is applied to texture each polygon properly without you worrying about “unfolding” it to fit properly.
It’s important to note that when applied to an object, a polygon-packing style Unique UVs projection only produces good results if you use a texture created specifically for the projection.
For more information about using Unique UVs projections to rendermap and object, see Rendermapping with Unique UVs.
• Angle Grouping, after deciding on a projection direction, groups neighboring polygons whose normal directions fall within a specified angle tolerance. This process is repeated until all of the object’s polygons are in a group. The groups—or islands—are then assigned to distinct pieces of the texture so that no two islands’ coordinates overlap each other.
This method is useful for unfolding an object’s geometry. Typically, the object is broken up along the planned seams in the projection. Then the angle-grouping style unique UVs projection is applied to the object, creating UV islands in accordance with the predefined seams.
Once you’ve generated the UV coordinate islands, you can heal them together in the texture editor to produce the object’s final unfolded UV coordinates. You can also reattach the object at the seams, and apply the unfolded projection to the entire object.
For more information about using Unique UVs projections to unfold an object, see Unfolding a Texture Projection.
Contour Stretch UVs Projection (Polygons Only)
Contour Stretch UVs projections allow you to project a texture image onto a selection of an object’s polygons. Rather than projecting according to a specific form, however, a contour stretch projection analyzes a four-cornered selection to determine how best to stretch the polygons’ UV coordinates over the image.
Contour stretch projections do not have the same alignment and positioning options as other projections. Instead, you select a stretching method that is appropriate to the selection’s topology and complexity. Also, contour stretch projections do not have a texture support. You can adjust them only from the texture editor.
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• Because they have no texture support, contour stretch projections cannot be transformed using the j key or the Render toolbar’s Modify > Projection command. • Contour stretch projections cannot be implicit. |
Contour stretch 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.
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Contour stretching can also be done using the Contour Stretch subprojection in the texture editor. Although the results are the same, the workflow is different. Contour Stretch subprojections are described [here]. |
Autodesk Softimage v.7.5