#Background Shadow
6 messages in this thread
How can I cast the shadow of my object onto a background bitmap image which I
am using it as my landscape? Without the shadow effect, my object looks like as
it is floating and has no relation to my landscape image.
Can some one please help me on this? Thanks in advance!
Paul
Paul,
If you have animator pro you can use this method or even a similar paint
package may work. Create an object which will represent your background and
orientate it into the correct perspective which will match your background
image – you can test this by turning on the background view in the views menu.
Make this object a bright blue (0,0,255) for diffuse, ambinent and specular
with no shininess. You will need to render twice: first render with the scene
with no background and no background object with alpha on and save as a
sequence of .tga files; for the second render change the material of your
foreground object to be the same blue as the background object and unhide it.
You can then render a flic with the a shadow cast onto the blue background
object. Take this flic into animator pro and fill the shadow with dark gray and
the blue area with black on every frame – use the seperate tool if necessary to
get the anti-aliased part of the shadow. Now, go back into 3ds and into video
post and set up the first entry as your background bit-map image, the second
entry will be the flic using rgb 0,0,0 or pseudo alpha, the third entry will be
the sequence of .tgas with the foreground object and alpha will be queue alpha
channel. Render and you're in business! A lot of work? Maybe, but that's why
you are paid so much <g>. I'll send you an invoice for one of my (until
recently) best-kept secrets <g>. Just kidding 🙂
Martin,
Thank you for your voluable tips! I can't help to think if there is an easier
technique. Is there a way for 3DS to write to the alpha channel? In other word,
if we can use the alpha channel as a mask during the rendering, then a lot work
can be saved. Is this possible now, or should we wait for it in the version
3.0?
Thanks again for the tips.
Paul
Paul,
Hey, many of the great special effects will be a lot of work but it pays off
later. I once read that to do the Star Trek space ship scenes outside the ship
they have to film about 4 or 5 passes of the model on the motion control rig to
get each element of lighting etc. that they need; they then combine them all
together to get what we see on TV. Anyway, if you want the shadow in
perspective there is no easier way, I know of, not without experimenting at
least. There may be a way to use the alpha channel seperately and offset it
from the image, but currently it's still a lot of work. Do you have HiresQFX
2.0? That has a way of compositing sequences of images at x,y co-ordinates
with other images. I haven't tried it but it might work.
It's in the current version. Turn on USE-ALPHA to add the alpha channel to the
rendered image. Turn on ALPHA-SPLIT to create a separate, additional file
containing nothing but the alpha channel.
– Jack
Jack,
how would you approach the "background_in_perspective_shadow" problem the Paul
is trying to achieve? I'm curious to hear how someone else would approach it.