Let´s say you have a XSI-Scene containing a camera with animated zoom. Since in messiah, the focal length parameter itself isn´t animatable you have to do two things. Transfer the animated Zoomdata to messiah in some way, and then convert it from focal length to zoom factor.
The first part is quite simple. Just creat a null in XSI and rename it to something like focal_length_value. Leave it in the World space 0,0,0. Then link your cameras focal length parameter to lets say the x-position of the null. Usually you animate the field of view parameter in XSI, so don´t forget to key or bake the focal length parameter in XSI also, otherwise the values are not passed to the null. You should end up with a null thats moving along the x-axis corespondingto the focal length value (eg. focal length:15 mm = x-position:15 units). Do not parent the nul under any other object.
Export your scene via PointOven as LWS or FXS. Don´t forget to export motions for nulls as well as cameras and objects.
Import the scene in messiah. Now you have all the needed values in messiah, only the focal length is now the x-position of some null. To change this go to the command panel and create a new variable. Set the target channel to camera zoom and the expression to [focal_length_value:xpos] or whatever axis you connected in XSI to the focal length parameter. At this point the camera zoom factor becomes animated according to the focal length you animated in XSI, which is very close but not exacty what you want. What you need now is some multiplier to convert focal length to zoom factor. To get this factor create a new camera in messiah. Go back to XSI and check the „film aperture y-value“ enter this value in „aperture height (inches)“ field in the newly created messiah camera. The use the minisliders to set the „Lens Focal Length“ of this cameara to 1. If you just enter the value, the Zoom Distance value will not update, but you need it to. Copy the generated Zoom Distance value and paste it as a multiplier into the variable you created before.
You should now have something like:
- Camera zoom
At this point the zoom distance animation should exactly correspond to your XSI camera.