The following small how-to tutorial assumes you have basic knowledge about 3D Studio MAX.
Most everyone in the field of computer graphics and animation will remember the movies like Terminator 2 - Judgement day and Jurassic Park. The very realistic computer graphics were partly due to the integration of the 3D animated footage with the environment (ie. the background). The backgrounds used in the movies was simply the footage shot on the location. In this small how-to we will concentrate on just a single static background image. If you want matching shadows of 3D objects in a static background or if you want to add a form of layering in a 2D background image for 3D objects so they can pass in front or in the back, please read on.
3D Studio MAX offers a special material type, the Matte Material, that will allow you to combine 2D backgrounds with the 3D scene in a very efficient and flexible manner. The remainder of this page will show you how to use the Matte Material and how to setup a basic scene.
Selecting a background to work with:
The first thing we need is a background we can work with. In the sample on this page I have chosen for a photograph of an office building. The geometry of the building in the following image is pretty basic which is just what we needed for this example. Note that you can download the MAX file along with the background image on the bottom of the page as a ZIP file.
The original background image
With the perspective viewport active, select a background using the Background Image function in the Views menu. Select the image you want to use as a background (building.jpg in our sample case) and don’t forget to switch the Display Background option to ON. For the aspect ratio, select the Match Rendering Output option (since we want our final rendering to match).
Next we also need to define an environment background so that it’ll show up during rendering. Use theEnvironment function, located in the Render menu for this. In the background section of the environment dialog set the Use Map option to ON and assign a bitmap to it. The environment background will now be located in one of the material editor slots (32 hits) (usually slot 1 by default).
Call up the material editor and for a bitmap select the same image you just selected for the background of the viewport. In the mapping list (under the Coordinates panel) select SCREEN as the mapping type. Now you have the right setup to work with, a background in the viewport we’ll be working with as well as a background for rendering.
Creating a matching geometric scene
The next thing we need to do is to recreate the basic geometry of the background in the 3D scene. This might sound harder than it actually is even though for large and complex images this can be a pretty time consuming task.
First we need to setup a camera to work with. Create a camera in the scene which will be the camera we will be rendering from. This camera should be placed in such a way that the grid in the camera viewport (ie. change the perspective view to the camera view) acts as the ‘floor’ of our scene. This will help you position the matching geometry later on.
Using nearly plannar boxes we will start to fit these boxes into the scene in such a way that the planes cover up the parts of the background image we want to be receiving shadows. The image below will give you the basic idea of what I have done to the original background image.
Background with matching geometry
Note that the image also shows a spotlight that brightens up the geometry. It is advisable to create lightning conditions which match the general direction of the light in the original background for reality’s sake.
As you can see, all the parts of the original image are now blocked by a 3D construction of boxes, planes, cylinders, and shapes. You will need to check out the original MAX file (located below) to get a full view on the actual scene. It is best to try to create the 3D scene in such a way that it closely matches the depth of the background image. Use all features and resources to your availability for this.
Creating the Matte Material
Call up the Material editor and select an unused slot to start a new material definition. For the type of material select the Matte/Shadow material, this will bring you into the Matte/Shadow parameters panel. Leave all the parameters at their default value, you can expiriment with those later on, but do switch the receive shadows to ON.
Assign this material to all the objects you have used to create the matching geometry. If you switch to shaded mode you will notice that the background image will be overlapped with the geometry (gray by default).
PLAY
You are now ready to play around with your scene. Note that you shouldn’t move the camera around because the geometry matching the background is directly related to your camera viewpoint. You can add lightsources and other objects into the scene to achieve effects like you can see in the image below.
A completely fake scene with correct shadows
