Masking with falloff ? - 3D-Palace Community Forums

roel018 · #1 01-05-2009, 10:04 AM

Hi all!

I'm trying to accomplish the following:
I have a scene where I have to mask out a portion of the scene so the background is visible on the masked portion. I do this by creating a closed spline, converting it to an Editable Poly, and applying a Matte/Shadow material to it.. this works, and I can animate the mask by adjusting the different vertices of the poly object. However, this creates a very sharp mask.. But what I want, is a mask with an edge I can adjust using i.e. a falloff map.. I need a soft edge of the mask, not a hard, sharp edge..

How can I accommplish this? So, I need a fade between the masked area and the not-masked... Hope some one can help me

Thnx all!
Roel.

ragupasta · #2 01-05-2009, 10:35 AM

Hey man.

Use a plane. Add a gradient ramp map to a new material slot in the opacity channel, set it to be radial. Remove the middle flag, set the type to be linear, open the output and hit invert, and enable color map, and right click the bottom left map point, set it to, bezier and draw the curve out to look like that in image #2.

There is a fair bit of tweaking to do to get it right, however this would be something I would do in post work, rather than inside a 3d app. Makes it easier to do in Photoshop/Compositing package.

roel018 · #3 01-05-2009, 10:56 AM

Hi! Thnx for your reply

However, this solution doesn't mask anything. It only adds a gradient falloff to the pane. However, I would need this pane with gradient to Mask the object it overlaps so I can see the background (with a falloff edge).. Besides that, I need to anymate the masked portion, so I'm not sure I can do this with a pane.. Also, I cannot accomplish this in for example After Effects because the scene construction and the nature of the scene's animation forces me to do it in 3DS Max..

ragupasta · #4 01-05-2009, 11:18 AM

If this plane is sat infront of what you want masked, then it will mask whatever it is you want masking out with a falloff like you wanted.
Animate the plane or a uvmap modifier's gizmo to get translation.
Without images to support what you want im guestimating, as that is a work around for what you asked in the above post.

If you say masking a background, why not put the background on a plane in the scene instead of using the environment rollout background option, and then this will work for you.

Other that that ive no idea what you want. It all makes sence to me!

roel018 · #5 01-05-2009, 11:46 AM

Hi!
Well by following your steps, all I get is a plane with a falloff edge (which is good), but without any masking effects. (I rendered the scene). So, if I place the scene in front of a simple box, I can still see the plane, but what I would like is, I would like to see the background in the position of the plane..

What I'm trying to accomplish is this:
I have a background picture of two mountains. There's the first mountain which, is in place A.
I have a second mountain, in place B, in front and slightly to the left of the first Mountain.. But from the cameras point of view they overlap for the biggest part. .. Still, this is all in the background image (photograph).

In between the mountains, I'm creating a volumetric cloud.. Now, this cloud has to appear in front of Mountain A, but behind Mountain B, so what I did was I created a closed spline, converted it to an Editable Poly, applied a Matte/Shadow mask to it, adust the outlines of the Poly so it followed the corners of Mountain B, and voila, I got what I wanted, however, the mask's edge I created (by applying the Matte/Shadow map to the spline) is too sharp, it needs a slight fade, a falloff.. I do not want it to just cut off.. Because now there's a hard edge between the fog in the distant and the Mountain in front of it....

Hope you understand what I'm trying to accomplish .. !

Hope to hear from you,
Kind regards
Roel

ragupasta · #6 01-05-2009, 02:21 PM

Hahaha, now I see what you mean. I still say this would be easier to do inside a compositing package, with a very basic rotoshape/rotospline/B-Spline. All rotoshapes ive used has a falloff.

Should be easy in After Effects as its layer based.

Renderpass Mountain A single frame as a .tga (need the alpha channel)
Renderpass Mountain B single frame as a .tga (need the alpha channel)
Render pass volumetric cloud. as a sequence so that noise and turbluence is seen in the cloud ect render as a .tga (need the alpha channel)

I would assume After Effects has a 3d section to it as most compositors do. Add each one to a 3d plane in AE and stagger them infront of each other. Mountain A at the back, vol cloud in the middle, and Mountain B at the front. Now animate the planes in 3d space to cause the parallax effect of distance between the mountains, and the alpha channels with take away the need to masking/rotoshapes.

Its really quite easy and very effective.