Choosing and Configuring Maps to Generate

Choosing and Configuring Maps to Generate

Each RenderMap property that you apply to an object can produce several different types of maps at once. Each type of map has its own unique options that, when combined with the general rendermap options, define its output image. When you regenerate the maps, all of the maps that you’ve activated in the current rendermap property are generated.

The following sections describe the available map types, and how to set the options for each one.

• Surface Color maps are described in Generating Surface Color Maps.

• Texel Coverage maps are described in Generating Texel Coverage Maps.

• Normal maps are described in Generating Normal Maps.

• UV Basis maps are described in Generating Basis Vector Maps.

• Surface Position maps are described in Generating Surface Position Maps.

• Depth maps are described in Generating Depth Maps.

Also described are the output file options (file name, format, and so on) common to all types of rendermap. The following section describes how to set those options.

In addition to the map-specific options, you must set the General rendermap options (those that are common to all map types) before generating your maps. These options are described in Setting General RenderMap Options (All Map Types).

Setting Output File Options

Each map that you generate with a RenderMap property requires a file name, path, file format, and bit depth for the output image. You should set these options in each map’s respective section in the RenderMap property editor.

For each activated map:

• Enter the output image’s path and file name in the Path text box, if you don’t want to use the default settings provided.

If Usr is on, the path is displayed as you entered it. If Res is on, the resolved path is displayed. You can enter a different path or use the Browse (...) button to change locations. Valid paths are displayed in white, invalid paths are red, and read-only paths are gray.

• Set the output image’s file format and bit-depth in the Format and Width lists, respectively. Note that changing the file format updates the file extension in the Path text box.

Because not all image formats can be output at all channel widths, the Width menu displays only available widths for the selected format.

Prepending Owner Names to Output File Names

If necessary, you can activate the Prepend owner name to output filenames option on the Advanced tab of the RenderMap property editor. This adds the name of the rendermapped object or cluster to the rendermap image file names.

For example, if you generate a surface color map and a normal map (called surface_color_map.pic and normal_map.pic, respectively) for a sphere named Sphere2, the resulting file names are Sphere2_surface_color_map.pic and Sphere2_normal_map.pic. Activating this option is essential when you’re generating rendermaps for multiple objects at the same time, as described [here].

Generating Surface Color Maps

Surface color maps bake a variety of different surface and/or illumination information into an image file. You can generate a variety of different surface color maps, all of which are configurable to varying degrees.

Types of Surface Color Map

Each time you regenerate the maps for a given RenderMap property, you can generate one of the following types of surface color map:

	Surface Color and Illumination bakes all object surface attributes, including color, illumination, bump, and so on, into the rendermap output image. Note that fast subsurface scattering effects are not included in the maps generated by the RenderMap tool.
	Surface Color Only (albedo) bakes object surface color into the rendermap output image, without considering the current illumination environment.
	Illumination bakes illumination information into the surface color map. This includes light color. Illumination maps can optionally include bump map information provided that the Consider Bump option is activated in the Surface Color Map options (see Setting Surface Color Map Options).
	Ambient Occlusion uses Softimage’s ambient occlusion shader to create a color representation of the extent to which the object is occluded by other objects, or the environment, at any given point. When you’re setting the RenderMap properties, you can adjust a subset of the ambient occlusion shader’s parameters to control the final output map. This is described in Setting Ambient Occlusion Options. Ambient occlusion maps can optionally include bump map information provided that the Consider Bump option is activated in the Surface Color Map options (see Setting Surface Color Map Options). Note that the results of cached ambient occlusion are not included in the map generated by the RenderMap and Ultimapper tools.

Bump-Map Considerations For Surface Color Maps

If you are generating a surface color map for a bump-mapped object, and wish to include the bump map information in the resulting image, you must apply the bump map to the rendermapped object in one of the following ways:

• A bump map generator shader connected to the Bump Map input of the object’s material node.

• A texture shader, with bump mapping active, connected to the Diffuse input of a surface shader that is, in turn, connected to the Surface input of the object’s material node.

When you generate a surface color map, the material node’s Bump Map and then Surface inputs are evaluated. If the shaders connected to either of these inputs perturb the shading normals and leave them perturbed, then the bump information is baked in; otherwise, only the “bumpless” surface is captured.

For example, while either of the render trees shown above produce correct surface color maps with bump, this render tree does not:

Deactivating Surface Attributes

When you generate certain types of surface color map, you can use the Disable Surface Properties options on the Basic tab of the RenderMap property editor to control whether or not specific surface attributes are included in the resulting image.

The Disable Surface Properties options control whether shadows, refractions and/or reflections, as well as the ambient, diffuse and/or specular lighting components on the rendermapped object appear in the output image. When any of these boxes is checked, the corresponding attribute does not appear.

Of course these surface attributes can only be toggled provided they are active to begin with. For example, if the object is Blinn shaded, but the Blinn shader’s specular component is deactivated, toggling the specular component in the RenderMap property editor has no effect.

In other words, these options are simply a mechanism to toggle surface attributes that are already activated for the object — not a mechanism for adding these attributes to the object.

Not all of the Disable Surface Properties options are not available for all types of surface color map. This is either because the corresponding attributes are not applicable to the map type, or because they are included automatically.

You set the Disable Surface Attributes options along with the other surface color map options, as described in the following section: Setting Surface Color Map Options.

Setting Surface Color Map Options

The surface color map options are located on the Basic tab of the rendermap property editor.

To set surface color map options

1. Apply a RenderMap property to one or more objects as described [here].

2. If necessary, on the Basic tab, activate the surface color map by checking the Enable box in the Surface Color section.

3. Set the surface color map’s output file options, as described [here].

4. From the Map list, choose the type of map to generate. The available types of surface color map are described [here].

5. If the rendermapped object(s) is bump mapped, you can toggle the Consider Bump option to specify whether the bump map is included in the output image (See [here] for information about rendermapping bump-mapped objects).

This option is not available for all of the surface color map types, some of which include bump mapping automatically. See Types of Surface Color Map for details.

6. If necessary, use the options in the Disable and Enable sections to control whether various surface attributes appear in the output image. For details about using these options, see Deactivating Surface Attributes.

7. Activate the Coverage in alpha channel option if you wish to include the output images’s texel coverage pattern when you generate the surface color map.

The texel coverage pattern indicates what percentage of the output image texel is located on the surface: black being no coverage and white being 100% covered.

You can also bake the texel coverage pattern into a separate map, as described in Generating Texel Coverage Maps.

8. If necessary, click the Surface Settings tab of the RenderMap property editor and set the Background Color to fill empty areas of the surface color map. Use the sliders to set any color you like.

9. If necessary, apply any of the color correction options described in the following section, Color Correcting Surface Color Maps.

10. If you are generating an ambient occlusion map, you can set additional ambient occlusion options, which are described in Setting Ambient Occlusion Options.

11. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

12. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

13. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Color Correcting Surface Color Maps

If necessary, you can apply a color correction process to your surface color maps as they are generated. This is especially useful when you are simultaneously generating multiple surface color maps, all of which need color correction.

To apply color correction to surface color maps

1. Activate and configure a surface color map, as described in the previous section, Generating Surface Color Maps.

2. From the Surface Settings tab, set the Color Correction > Mode to one of the following:

- Grayscale (Average) creates a grayscale rendermap image based on the average of each pixel’s RGB values.

- Grayscale (Intensity) creates a grayscale rendermap image based on each pixel’s intensity value.

- Negative creates an inverted version, or negative, of the texture on the rendermapped object.

- Custom allows you to manually set the color correction options.

3. If you set the Mode to Custom, you can set the Gamma, Contrast, Hue, Saturation, and Level values.

Setting Ambient Occlusion Options

Ambient occlusion works by firing rays into a predefined hemispherical region above a given sampled point on an object's surface in order to determine the extent to which the point is blocked - or occluded - by other geometry.

If you are generating an ambient occlusion map using the rendermap tool, you can adjust the following parameters, which are located on the Surface Map Settings tab of the RenderMap property editor:

• Samples specifies the number of sample rays used to determine occlusion. Higher settings produce a smoother result but take longer to generate the ambient occlusion map.

• Spread defines the size of the cone from which sample rays are fired. A value of 0 samples only in the direction of the surface normal, while a value of 1.0 samples the entire hemisphere above the sampled point.

• Dark Color is a color used to scale the ambient lighting where the object is completely occluded. If the object is partially occluded, this color is mixed with the Bright color.

• Bright Color is a color used to scale the ambient lighting where the object is completely unoccluded. If the object is partially occluded, this color is mixed with the Dark color.

These parameters are actually a subset of Softimage’s ambient occlusion shader’s parameters. For detailed information about the ambient occlusion shader, see Ambient Occlusion [Indirect Illumination].

Generating Texel Coverage Maps

When you generate rendermap images, each one has a texel coverage pattern that indicates what percentage of the output image texel is located on the surface: black being no coverage and white being 100% covered. Practically speaking, this pattern can be used as a matte for the map images.

The Texel Coverage map options allow you to burn this coverage pattern into an image file.

You can also store the texel coverage pattern in the alpha channel of a surface color map, as described in Generating Surface Color Maps.

To set texel coverage map options

1. Apply a RenderMap property to one or more objects as described [here].

2. On the Maps tab, activate the texel coverage map by checking the Enable box in the Texel Coverage section.

3. Set the texel coverage map’s output file options, as described [here].

4. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

5. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

6. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Generating Normal Maps

Normal maps allow you to burn the rendermapped object’s normals into a file where they are stored as RGB values. Games developers use normal maps to create complex high-detail surfaces on low-resolution, low-polygon-count objects.

Typically, this is done by baking the surface and normals of a detailed, high-resolution object into maps that can be applied to the object’s low-resolution counterpart. In Softimage, you can easily perform these types of map transfers using the Ultimapper tool, which uses RenderMap to burn the necessary maps. For more information about the Ultimapper tool, see Transferring Surface Attribute Maps (Ultimapper).

Data in normal map files is stored in a biased form. To ensure that they are always in the 0 to 1 range, the X, Y, and Z of the normal are stored as:

(x+1)/2,(y+1)/2,(z+1)/2

To get the unbiased, original normal value, use:

r*2-1,g*2-1,b*2-1

Normals can also be burned into a color at vertices (CAV) property by using RenderVertex instead of RenderMap. This is described in RenderVertex

To set normal map options

1. Apply a RenderMap property to one or more objects as described [here].

2. On the Maps tab, activate the normal map by checking the Enable box in the Normals section.

3. Set the normal map’s output file options, as described [here].

4. From the Space list, choose how the normal vectors should be encoded:

- If you choose Object space, the vector is represented relative to the coordinate frame of the object. Rotation, translation, and scaling of the object do not have an impact on the result.

- If you choose World space, the vector is represented relative to the scene root. Rotations and scaling of the object affect the result. Translation never affects normals.

- If you choose Relative to UV Basis, the vector is represented in the local space defined by the UV basis; that is, the coordinate frame defined by the tangent (X-axis), binormal (Y-axis), and interpolated normal (Z-axis).

This is known as tangent space and it is the most common coordinate system to store normals for a normal map. This is particularly true if you're planning on deforming the model at all (for example, using skinned animation). Normal maps generated this way are also very useful for bump-mapping in games.

The tangent and binormal (U and V basis, respectively) are computed based on a texture projection that you will specify in step 6.

The U and V bases can also be burned into a separate map, as described in the following section, Generating Basis Vector Maps.

5. From the Type list, choose the type of normal to burn into the normal map:

- The Interpolated Normal is computed by interpolation across the triangle of the rendermapped surface. It is not affected by bump mapping, and is always the normal of the surface being rendermapped.

Computing this normal does not involve evaluating the surface shader, and is much faster to compute than the Sampled Normal.

If the Space option is set to Relative to UV Basis, burning the interpolated normal is generally not useful, since the coordinate frame is defined based on the interpolated normal to begin with. In such cases, (0,0,1) is always returned as the relative normal.

- The Sampled Normal is the normal used for shading after ray-casting and evaluating the surface color. As such, bump mapping affects the result.

In cases where the ray-casting “catches” a surface other than that of the rendermapped object (for example, if the Ignore RenderMapped Objects parameter on the Advanced tab is activated), the normals of the other surface are burned into the map.

If there is no bump mapping, and the rendermapped object’s surface is “caught” by the sampling, the sampled normal matches the interpolated normal.

The Sample Normal setting is useful for computing the normals of a high-resolution object relative to the coordinate frame on a low-resolution object, as defined by the U/V basis and the interpolated normal.

- Geometric Normal: This is the normal of the geometric triangle being sampled. It is not affected by bump mapping, and is always the normal of the surface being rendermapped.

Computing this normal does not involve evaluating the surface shader, so it is much faster to compute than the Sampled Normal.

6. If you had previously set the Space option to Relative to UV Basis then, from the UV Basis options on the Advanced tab, do one of the following:

- Make sure that the Automatic Basis option is activated and then, using the Texture Projection (for automatic generation) options, specify a texture projection to use when calculating the U and V bases.

- Deactivate the Automatic Basis option and then, using the User-Defined Basis options, specify a color at vertices (CAV) property to use when calculating the U and V bases.

In most cases, the texture projection specified in the Format options on the Basic tab is ideal for computing the UV basis because this projection tends to have low sheering in the UVs.

7. If necessary, deactivate the Force perpendicular basis option.

When activated, this option first changes the V-basis to ensure it is perpendicular to the (current) U basis and the interpolated normal. It then changes the U-basis to ensure it is perpendicular to the new V basis and the interpolated normal. The interpolated normal itself never changes.

8. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

9. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

10. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Generating Basis Vector Maps

Together with an object’s interpolated normal, the U basis (tangent) and V basis (binormal) define a coordinate frame on the object’s surface. Conceptually, the U and V bases are supposed to be tangent to the surface, while the interpolated normal is perpendicular to the surface. This coordinate frame is useful for relative normal computations for bump mapping in games.

The Basis Vector map options in the RenderMap property editor allow you to burn the U and V bases into separate maps.

As with normal maps, data in U and V basis map files is stored in a biased form. To ensure that they are always in the 0 to 1 range, the X, Y, and Z of the vectors are stored as:

(x+1)/2,(y+1)/2,(z+1)/2

To get the unbiased, original vector value, use:

r*2-1,g*2-1,b*2-1

The U and V bases can also be burned into color at vertices (CAV) properties by using RenderVertex instead of RenderMap. This is described in RenderVertex

To set basis vector map options

1. Apply a RenderMap property to one or more objects as described [here].

2. From the UV Basis options on the Advanced tab, do one of the following:

- Deactivate the Automatic Basis option and then, using the User-Defined Basis options, specify a color at vertices (CAV) property to use when calculating the U and V bases.

3. If necessary, deactivate the Force perpendicular basis option.

4. On the Maps tab, activate one or both basis vector maps by checking the Enable U and/or Enable V boxes in the Basis Vectors section.

5. Set the U and V basis maps’ output file options, as described [here].

You’ll need to set a separate path and file name for each basis vector map. The Format and Width settings, however, apply to both the U and V map.

6. From the Space list, choose whether the basis vectors should be encoded in object space or world space:

- If you choose Object space, the vectors are represented relative to the coordinate frame of the object. Transforming the object does not have an impact on the result.

- If you choose World space, the vectors are represented relative to the scene root. Rotating and scaling the object affects the result.

7. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

8. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

9. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Generating Surface Position Maps

A surface position map burns the sampled position of an object’s surface into a map. It stores the raw (X, Y, Z) position as a color, without biasing. For this reason, you will want to use a file format that supports floating-point
bit-depth, or ensure that the object’s coordinates are between 0 and 1.

To set surface position map options

1. Apply a RenderMap property to one or more objects as described [here].

2. On the Maps tab, activate the surface position map by checking the Enable box in the Surface Position section.

3. Set the surface position map’s output file options, as described [here].

4. From the Space list, choose whether the surface position should be encoded in object space or world space:

- If you choose Object space the position is represented relative to the coordinate frame of the object. Transforming the object does not have an impact on the result.

- If you choose World space, the position is represented relative to the scene root. Transforming the object affects the result.

5. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

6. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

7. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Generating Depth Maps

Depth Maps, also called height maps, are grayscale representations of the height of every point on an object’s surface. Depth maps are often used by game developers to create a more realistic bump-mapping effect called parallax mapping, which simulates the correct displacement you perceive on an object’s surface, based on the camera’s point of view.

Depth maps can also be burned into a color at vertices (CAV) property by using RenderVertex instead of RenderMap. This is described in RenderVertex.

To set depth map options

1. Apply a RenderMap property to one or more objects as described [here].

2. On the Maps tab, activate the depth map by checking the Enable box in the Depth section.

3. Set the depth map’s output file options, as described [here].

4. Activate and configure any other maps (surface color map, normal map, and so on) that you wish to generate using the current rendermap property. For a list of available maps, see [here].

5. Set the general rendermap options, described in Setting General RenderMap Options (All Map Types).

6. When you’re finished, click the Regenerate Maps button to generate all activated maps.

Autodesk Softimage v.7.5