The seats you mapped in the previous lesson appear too uniform: They lack individual signs of wear and tear. Now you will introduce another level of randomness to the seat material by adding sub-maps that contain blemishes and other discolorations.

To accomplish this, you will composite two layers of sub-maps onto one another. One layer will contain the four diffuse colors you specified in the previous lesson, the other layer will contain sub-maps with a mixture of image maps of dirt patterns.

Set up the lesson:

• Continue from the previous lesson, or open multi_maps_02.max.

Create the composite layers:

1. If the Material Editor is not already open, press M to open it.
2. In the Slate Material Editor active View, click (Zoom Extents) so you can see both the material node and the Multi/Sub map node.
3. Drag a Composite map (Maps Standard Composite) from the Browser. In the active View, drop the map on the wire that connects the Multi/Sub map and the seats material.

   3ds Max displays a cursor that indicates you are inserting the map into the wire. Release the mouse when this cursor appears.

   
4. After you release the mouse, 3ds Max displays a pop-up menu. On the pop-up menu, click Layer 1.
   

   This incorporates the Multi/Sub map as the base layer of the composite.

5. On the Slate Material Editor, press L to arrange the layout of the material tree.
   

Add a Multi/Sub map to Layer 2:

1. Double-click the Composite map node to display its parameters.
   
2. On the Composite Layers rollout, click (Add A New Layer).
3. Drag a second Multi/Sub-Map (Maps mental ray Multi/Sub-Map) from the Browser into the active View, then wire the new Multi/Sub map to the Layer 2 component of the Composite map.
   
   TipPressing L again can help you see all the nodes. So can the other Slate Material Editor navigation tools. After you’ve used a navigation tool such as Zoom or Pan, right-click an empty area of the active View so you can select material and map nodes once again.
4. Double-click the new Multi/Sub map node to display its parameters.
5. On the Multi/Sub-Map Parameters rollout, set Number Of Colors/Maps To Use to 6.

   This time, rather than change colors, you will add six bitmap images to the sub-map.

Add the first dirt bitmap to the Multi/Sub map:

1. Drag a Bitmap from the Browser into the active View.

   3ds Max opens a file dialog.

2. On the Select Bitmap Image File dialog, highlight dirt1.jpg and turn off Sequence (otherwise, 3ds Max opens all the dirt files as an animated sequence!). Click Open.
   

   The thumbnail at the bottom right of the dialog gives you an idea of what the dirt1.jpg image looks like.

3. Wire the new Bitmap node to the Color/Map #1 component of the new Multi/Sub map.
   
4. Double-click the new Bitmap node so you can see its parameters.
5. On the Coordinates rollout, make sure Use Real-World Scale is turned off.
   

Add the other bitmaps to the Multi/Sub map:

1. Repeat the previous procedure for the remaining bitmaps, dirt2.jpg through dirt6.jpg. Wire the Bitmap node for dirt2.jpg to the Color/Map #2 component, dirt3.jpg to the Color/Map #3 component, and so on.
   

   All six bitmaps wired to the second Multi/Sub map

Define how the two layers composite together:

1. Double-click the Composite map node to see its parameters.
   

   The Operations drop-down list for each layer is set to Normal, which means that the layer with the highest number obscures all layers beneath it. You need to add an operation that will blend the layers together.

2. On the Layer 2 rollout, click to open the Operations drop-down list, and choose Multiply.
   

   Now the Composite map combines the color and dirt map layers.

3. Make sure the Camera-Seats viewport is active, then press F9 to render the scene (leave the rendered frame window open).
   

   Notice how each group of seats shows the same dirt map. The dirt1.jpg map is applied to all objects in the scene with an ID of 1. The dirt2.jpg map is applied to all objects in the scene with an ID of 2, and so on. You now need to distribute a random mix of all six dirt maps for all seats groups in the stadium.

Define the sub-map distribution method and fine tune the composite image:

1. Double-click the Multi/Sub map node that contains the dirt bitmaps, so you can see its parameters. On the Multi/Sub-Map Parameters rollout, open the Switch Color/Map Based On drop-down list, and choose Random.
   
2. Click Render to render the scene again (still leaving the rendered frame window open).
   

   Now, all six dirt maps appear at random for all seats groups in the stadium. The dirt patterns, however, stand out too clearly.

3. Double-click the Composite map node to see its parameters.
4. On the Layer 2 rollout, change the Opacity setting to 35.0.
   

   The dirt layer is reduced in visibility to 35 percent of its full opacity.

5. Click Render to render the scene once more.
   

   The dirt maps appear more faded, giving the seats a subtle variation that appear more realistic.

Save your work:

1. Save the scene as my_stadium_submaps_completed.max.
2. If you wish, open the file multi-maps_completed.max and render the Camera-Seats viewport to see a finished version of the stadium scene.