Camera looking at a reference plane

You can use Ref mode to quickly set up the camera so that it is looking straight down at a reference plane.

1. Set the current reference plane.
2. Activate the Ref transform mode (in Ref mode, values are relative to the active reference plane).
3. Select the camera interest, and in the Transform panel enter X=0, Y=0, Z=0.
4. Select the camera and set X=0 and Z=0. You can also set the Y, or just go to the viewport and use the mouse scroll wheel to pull back from the reference plane.

Here’s a script that does this for you. The script works with a default Softimage camera rig: just select some part of the camera rig and the script will figure out the rest.

var o = ( Selection(0).IsClassOf( siX3DObjectID ) ? Selection(0) : Selection(0).Parent3DObject );

var c = null;
var ci = null;
switch ( o.type ) {
	case "camera" :
		c = o;
		ci = c.Interest; 
		break;
	case "CameraInterest" :
		c = o.Parent3DObject.Camera;
		ci = o;
		break;
	case "CameraRoot" :
		c = o.Camera; 
		ci = c.Interest; 
		break;
	default :
		LogMessage( "Cannot find the camera and camera interest. Please select part of a camera rig." ); 
} 

if ( c != null & ci != null )
{
	// Translate Camera Interest
	Translate(ci, 0, 0, 0, siAbsolute, siObjCtr, siObj, siX, null, null, null, null, null, null, null, null, null, 0, null);
	Translate(ci, 0, 0, 0, siAbsolute, siObjCtr, siObj, siY, null, null, null, null, null, null, null, null, null, 0, null);
	Translate(ci, 0, 0, 0, siAbsolute, siObjCtr, siObj, siZ, null, null, null, null, null, null, null, null, null, 0, null);

	// Translate Camera
	Translate(c, 0, 0, 0, siAbsolute, siObjCtr, siObj, siX, null, null, null, null, null, null, null, null, null, 0, null);
	Translate(c, 0, 20, 0, siAbsolute, siObjCtr, siObj, siY, null, null, null, null, null, null, null, null, null, 0, null);
	Translate(c, 0, 0, 0, siAbsolute, siObjCtr, siObj, siZ, null, null, null, null, null, null, null, null, null, 0, null);
}

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