Discreet combustion 2 and 3ds max 5

Michael Hurwicz

November 28, 2002

Discreet combustion 2 is a high-end video compositing program, in the same category as Adobe After Effects. As such, combustion is primarily designed to combine video clips "vertically" and add effects (as opposed to stringing clips together "horizontally" and adding transitions, in the way that a video editing program like Adobe Premiere does, for example).

Combustion has amazing compositing features, including 3D compositing, sophisticated color correction, tracking and stabilizing (to "paste" a logo on an object, for instance, or to correct for camera jitter), a 2D particle system, and excellent vector paint tools. (See the links at the end of this article for sources of more overview information on combustion 2.) These features make combustion 2 worthy of consideration by anyone looking for professional-level video compositing software.

However, there is one group that is uniquely positioned to benefit from combustion's features: users of Discreet's 3ds max 3D modeling and animation software. As a 3ds max user, you can interface with combustion 2 in four different ways:

1. You can import 3ds max output into combustion 2.
2. You can assign any combustion output as a map in 3ds max.
3. You can use combustion 2 to "paint" surfaces in 3ds max.
4. You can create a combustion file directly from 3ds max.

Importing 3ds max Output into combustion 2

If you're familiar with the Video Post Queue in 3ds max (shown below in Figure 1), you have a feeling for what happens when you import 3ds max content into combustion. The 3ds max Video Post Queue allows you to hierarchically composite images, effects and events with 3ds max scenes. For instance, in Figure 1, you start with the Front view, add a lens effects glow, use Digimation's Fractal Flow plug-in to apply fractal distortion, and finally output to a file, combmap6.avi.

Figure 1. The 3ds max Video Post Queue.

Combustion is like a super Video Post Queue. You can take 3ds max output, plop it into layers in combustion and work all kinds of magic with it.

3D in combustion

3ds max 5 can render a wide variety of file types, and combustion 2 can import most or all of them. This includes, for instance, AVI, BMP, CIN, EPS, FLC, JPG, PNG, MOV, RLA, RPF, TGA and TIF.

Especially interesting for 3ds max users is RPF, a format which allows you store up to 13 channels of information within your rendered file. You can then apply combustion's 3D Post effects to the 3ds max output based on these RPF channels. For example, combustion 3D Post operators can be used to add texture maps, depth of field, 3D glow, 3Dlens flare, 3D fog, or motion blur based on pixel velocity.

Data about cameras and lights is also imported into combustion and stored in separate layers.

The basic process consists of three steps:

1. Render a 3ds max scene as a sequence of RPF files.
2. Import the sequence into combustion 2.
3. Apply combustion's 3D Post operators to the sequence.

While most graphics formats divide content into at most two channels (color and alpha), the RPF format delivers content in a number of "G-buffer" channels, including Z, material effects, object ID, normals, transparency, color, UV coordinates, velocity and several others. Each channel is separately selectable in combustion. Thus, for example, if you assign a Material Effects Channel number to a material (or a sub-material within a multi/sub-object material) in 3ds max, you will be able to apply combustion 3D Post effects just to objects or sub-objects painted with that material.

In addition, combustion 2 provides a multi-layered 3D workspace. It's not like 3ds max, where you place individual objects on a 3D grid. Rather, you place objects on layers, and then define the distance and angle of each layer from the camera. Combustion 2 then creates a parallax effect when you move or animate the camera. You can adjust lighting and create depth of field effects. Objects can also cast shadows from one layer to another. The shadows conform to the 3D scene correctly, using the information in the Z and normals channels.

You can use the velocity channel in the RPF output to determine how much motion blur gets applied in combustion 2. As far as the blurring goes, it's basically the same as image motion blur in 3ds max. However, it's nice to be able to adjust blur as you're compositing, rather than having it fixed in the 3ds max output.

All in all, the RPF import feature in combustion gives you a rich and flexible environment in which you can continue to work intelligently with 3ds max objects while integrating them with other types of content.

Tips and Traps

Here are four tips for importing RPF files from 3ds max into combustion:

1. 3ds max renders one RPF file per frame. 3ds max numbers the files sequentially. For example, if the name you provide is abox2, you'll get abox20000.rpf, abox20001.rpf, abox20002.rpf. Combustion can get confused if your file names start similarly. For instance, it may see a series based on abox1 and a series based on abox2 as a single series. One way to avoid confusion is to start each sequence differently. For example: a_box and b_box. You can also control the naming and numbering using [####]: for instance abox1_[####] and abox2_[####].
   
2. What Combustion refers to as the "Material ID" G-buffer channel (as shown in Figure 2 below), 3ds max calls the Material Effects Channel.
   



Figure 2. The "Material ID" G-buffer channel in combustion is the 3ds max Material Effects Channel

Thus, if you want to use the "Material ID" channel in combustion, you have to assign a Material Effects Channel number to your material in 3ds max 5. (As shown, circled in red, in Figure 3 below.)

If the Material Effects Channel number in 3ds max is 0 (the default), combustion 2 will not recognize it, and your object will not show up in combustion when you select the "Material ID" G-buffer channel, instead of being colored like the two balls in Figure 2 above.




Figure 3. The Material Effects Channel in 3ds max, set to 1.

3. The "Material ID" channel in combustion is commonly used to apply different textures to different objects or sub-objects. Textures will not apply correctly in combustion 2 unless your 3ds max objects have maps applied to them in the Material Editor. This is a bit counter-intuitive: You might think there'd be no need to apply maps in 3ds max, since you're planning to do it in combustion 2. In reality, if you assign the pink material shown in Figure 4 below to an object, you won't be able to use the "Material ID" in combustion to apply textures to the object, because no maps have been applied.

   

   Figure 4. Click on one of the "None" buttons to begin the process of assigning a map to a material in 3ds max.

4. If you create an RPF with more than two material effects channels in 3ds max (let's say four), and apply a "Show G-Buffer" operator in combustion to reveal the G-buffer information, combustion may not display the material effects channels correctly via the "Show G-Buffer" operator. Specifically, Under "Material ID" in the "Show G-Buffer" operator, combustion may display different material effects channels as a single color, so that you can distinguish them. This appears to be a bug in the "Show G-Buffer" operator. I never spoke to Discreet support about it. It doesn't seem to have any effect on output, though. When this has happened to me, combustion has still recognized all the material effects channels correctly in contexts other than the "Show G-Buffer" operator, and applied texture maps and other effects correctly.

Assigning combustion Output as a Map in 3ds max

There is a "Combustion" material type in 3ds max, as shown in the 3ds max 5 Material Map Browser in Figure 5.

Figure 5. The Combustion Material Type in the 3ds max 5.

This material allows you to use combustion 2 to create an map which can be applied to 3ds max objects, and which has the unique feature of being updated in 3ds max when the combustion image changes (a feature Discreet calls "Live Edit"). The material updates in the Material Editor. In addition, if "Show Map in Viewport" is selected in the Material Editor (by clicking the icon circled in yellow in Figure 6 below), the material is updated in shaded viewports .

The process for creating a Combustion material is as follows:

1. Assign a Combustion map to a material. For example, you can start by clicking one of the "None" buttons shown in Figure 4 above. Then select "Combustion" in the Material Map Browser, as shown in Figure 5.
   
2. Under "Project" in the Combustion Parameters rollout in the Material Editor, do one of the following:
• Click on the gray bar on the left (circled in red in Figure 6) to open an existing combustion file. You don’t even need to own combustion to use this feature. If someone gives you a combustion workspace and all the footage in it, you can apply it as a map. You won't be able to edit it, but it will appear on your object in 3ds max.
• Click on "Edit" on the right (circled in green in Figure 6) to open a new combustion file.



Figure 6. Creating a combustion material in 3ds max 5. Click the "Show Map in Viewport" icon (circled in yellow) if you want to update shaded viewports with the combustion material. Clicking "Edit" (circled in green) opens a new combustion file. Clicking the gray bar circled in red opens an existing combustion file.

3. Create your graphic in combustion. For example, you could create a new layer (Object, New Layer), add a Paint operator to the layer, and use combustion's vector paint tools to create a graphic. Or use any of the other outputs, such as particles or footage.
   
4. In the 3ds max Material Editor, click on "Operator" in the Combustion Parameters rollout.
   
5. In combustion, select the operator you want to use to update the 3ds max material.

When you go back into 3ds max, the material in shaded viewports should be updated with the new material. You may have to click on the material in the Material Editor to get that to update.

Using combustion 2 to "Paint" Surfaces in 3ds max

You can also draw directly on your 3ds max object, Here's the process:

1. Start with the process described in the previous section.
2. In the Combustion Parameters rollout in the Material Editor, click "Paint."
3. In combustion, select a drawing tool, such as the paint brush.
4. In 3ds max, move the cursor (now in the shape of a pen) over your object.

This is probably as close as you'll ever come to drawing directly on 3ds max objects using an external program. It makes it easy to experiment in combustion and continually monitor the results in 3ds max.

A couple of tips:

• The live link between the two programs may break for various reasons. If it does, you may be able to get back on track by closing the combustion workspace and clicking on the gray bar circled in red in Figure 6 to open the combustion file again. Kind of like rebooting Live Edit.
• Click on "Operator" in the Combustion Parameters rollout and select the Paint operator in combustion before clicking on "Paint" in 3ds max.

Creating a combustion File in 3ds max

You can create a combustion file directly from 3ds max at render time. Here's one way of doing it:

1. In the Common Parameters Rollout, assign a file name in the "Render Output" section, as if you are doing a normal render. You can deselect "Save File" if you don't actually want this file, but name it anyway.
   
2. Do the following for each element, such as alpha and diffuse map, that you want to render:
   
• In the Render Scene window in the Render Elements rollout, click on "Add" (circled in red in Figure 7 below). The Render Elements popup appears, as shown in Figure 7 below.
  
• Select an element that you want in the combustion file.
  
Each element appears in the Element Rendering List (just below the "Add" button).


3. Click "enable" in the "output to combustion" section.
   
4. Render.
   

Figure 7. The Render Elements Rollout and Popup

Each element shows up in a separate layer in the combustion file. This is an efficient and flexible way of getting 3ds max content into combustion.

The only part of this process that I found a bit non-intuitive at first was step 1. I couldn't understand, since all I wanted was the combustion file, I had to define a main output file, too -- though I didn't have to save it. However, a source at Discreet explained it this way: "If you don't have a filename set in your main output you will have to manually enter a name for each layer. A quick way of setting all the names at once is to set the 'base name' in your main output then simply not check the 'save output' box." Then, for each of the elements you choose to render in steps 2 and 3, 3ds max automatically creates a separate output file, of the same type as the main output file. Thus, if your main file is test.avi and you output two elements (say, the alpha layer and the diffuse map), you will end up with four separate files: test.avi, test_Alpha.avi, test_Diffuse.avi, and test.cws (the combustion file).

You can change the default names and types of the element files, or disable output of a file completely, in the Element Rendering List. You can also change the default name of the combustion file, in the "output to combustion" section.

Combustion vs. After Effects

Adobe's After Effects is the most popular program for microcomputer-based video compositing. Given the popularity of other Adobe products (Photoshop in particular) and the increasing integration across the Adobe product line, After Effects tends to be at the top of a lot of people's lists when they go shopping for video compositing software.

3ds max users, however, may want to think twice before following the crowd, given the extensive integration that Discreet has achieved between 3ds max 5 and combustion 2.

Josee Belhumeur of Discreet contributed to this article.

Links

Creative COW combustion forum

Creative COW 3ds max forum

Inside Combustion 2 (a good review)

Animation World (reviews, articles)

Discreet combustion 2 (a review)

combustion 2 (a review)

Discreet combustion 2 (a review)

Discreet home page

Discreet forums