Invisible Mesh or Object that can show shadow

[Guest_imported]

Sorry for my bad englich....but i try

I will put in a Scene an DV-avi Video as Background..per example the video shows a bridge...now i will let fly an Object under this bridge...
So i will put Invisible Objects on this bridge (the bridge from the avi Background)

How can i make invisible Objects (or Mechs)?

In german

Ich habe vor,in einem meiner Videoprojekte ein DV-avifile als Hintergrund in 3D Studio Max zu setzen.Das Video zeigt zb eine Brücke und ein Fluss...
Nun will ich zb ein kleines Raumschiff unter diese Brücke hindurchfliegen lassen und über den Fluss weiterfliegen lassen,sodass der Fluss den Schatten des Objektes zeigt.
Wie kann ich das anstellen?
Ich dachte mir mit unsichtbaren Objekten,die dennoch Schatten werfen...ich bedecke also zb den Fluss mit einer unsichtbaren Plane,die den Schatten zurtückwirft...genauso will ich die Brücke mit unsichtbaren Objekten zupflastern,sodass es den Anschein hat,dass das Raumschiff,wenn es von oben herab heranfliegt,hinter der Brücke nicht sichtbar ist.

Kann mir jemand bitte Tips per E-Mail geben?
Danke

Goik
goik@vo.lu

 

[azhdeem]

If I understand you right, you want to create something that will make it so that your object will appear to interact with the background.

The way to do this is to have your avi in the viewport and create several flat planes where you want your object to be behind, under, etc... It may take a while to get everything where it is supposed to be and depending on what the avi is doing you may have to animate the planes to move along with the avi.

Then you will need to try to set up your lights in the scene to match the lighting in the avi. This is important in order to get shadows to cast properly.

After you get the objects set up 3-dimensionally and the lights right, select all the planes and assign a "matte" material texture to them (this might not be the right name for it, I don't have 3D Studio in front of me right now to check). This should make the objects "invisible" in the scene but they should still cast shadows and allow your objects to interact with each other.

Let me know if this helps.

Jer
azhdeem@hotmail.com