fading out materials HELP ASAP

[schmoron13]

I'm animating a reinforced concrete wall that rocks back and forth, but rather than define the wall with a certain foundation, my boss wants to simply "dissolve" the foundation downwards. I did a mockup like this:

 

Initially, I thought I could cutout the still, and then using after effects (since I'm compositing the animation anyways) simply insert that still (as a screen?) and be done with it. Unfortunately, it's not working at all. I can't seem to "cutout the shape" and then stick it on the bottom of the animation.

 

I see two possible solutions: the first is to create an alpha channel and then simply put that file in there, but as a) I've never used an alpha channel and don't know squat about it, and b) it's superimposed on part of the existing file, I'd assume that would be hard to do.

 

The second option is to create an effect in the material that mimicks this....sort of a fadeout within a material. I was wondering if this is even possible? would it be better to do that with say, an env. fog that caps at a point, so it dissipates and thereby "dissolves" the object?

 

I'm CONFUSED!!!!!

 

-doron

[Paulcalif]

One approach is to use sub-object animation, on the verticies. The verticies that make up the top edge would be positioned at the top for frame 0, then, at the end frame, move the verticies to where they are in your illustration.

 

Put the mapping modifier above the edit-mesh, or poly modifier, so the mapping doesn't squash as the vert's move down.

 

Another way would be to use morph targets, and animate them. You would model the two versions of the concrete; the full version, and the 'melted' version. Using this technique, it is important that all meshes(the morph targets) are derrived from the same mesh. By animationg the morph percentage, the mesh will blend(morph) from to another over time.

 

Paul

[schmoron13]

thanks for the reply paul, but I think you're looking at the wrong aspect. I simply want the bottom of the concrete block to dissapear. It shouldn't be animated. Simply, I want the block to appear as if it continues endlessly, but rather than do it in a solid manner, I want it to LOOK faded out.

 

 

Another way of putting it is simply, if it's a "section of a wall," I want to illustrate that the portion that ends in the illustration is not the definitive end of the piece (which would be assumed if the bottom was a solid line. I'm kind of going for that effect of a "half drawn object" where on one end, the object is simply a rough sketch but as the eye progresses across said object, it become whole, thereby showing what the structure looks like, without defining its proportions definitively...

[3d-doctor]

if you in max have you considered particles

i did something moreor less similar to this earlier this year using max and sandblaster where using a invisible proxy of the wall and invisible particles you could build otr demolish the wall to suit

metaparticles could give you the softer edge

i think sandblaster is now included into max4+5

have a look.............

[David Barbarash]

Hmm... since you're composting to a white background, if you're using 3d max, you could create a mix material having one part your concrete map, the other being a gradient map in the opacity slot. You can then change how much wall shows up and where the fade begins by editing the gradient. I haven't tried it in this particular use before, but in theory it should work. Keep us posted!

 

David Barbarash

david@tencza.com

[TAKA]

David is right.....using the Opacity map should solve this easily......

plus if you want to composite it on any background, just create an alpha channel of ur animation.

 

In max it's simple.

Open the render dialog box.

expand the render elements tab.

Choose "add" and select alpha.

that's all.

Now when u render ur animation or still u get 2 files: for for the original view and a grayscale alpha channel....

 

good luck

[schmoron13]

thanks guys for all the help I still havn't gotten it quite right, but here's an update:

 

I've done the following:

 

Taka, this is gonna sound retarded (and show my ignorance of the alpha channel), but once I have those two files, what do I do? I'm really at a loss. How do I incorporate them in After Effects?

 

-thanks again for ALL THE HELP AND ENCOURAGEMENT...y'all are life savers

 

-doron

[Tony]

If you are useing a gradient ramp map you need to set the mapping to planar and rotate the map -90 in the material w, I tried it and it works great. If you apply a box uvw I got the same result as you did, the inside of the material shows.

 

You should only need the gradient in the main opacity slot.

 

Tony

 

 

[ August 06, 2003, 09:00 PM: Message edited by: Tony ]

[TAKA]

In aftereffects

import both files (the concrete render and alpha channel)

Add them to the timeline with the concrete render file on top of the alpha.

Select the concrete render and add an "Set matte" effect.

In the timeline, expand the set matte effect, and change the "Take matte from layer" to the alpha channel file we imported in the begining.

Change "Use for matte" to "lightness"

 

And that's it

now u can add other background or other footage underneath these 2 files in the timeline.

 

PS: if the opacity is inverted check "Invert matte" to "On"

 

Hope this makes sense

 

Cheers

[digtlpete]

If you simply want an object to disapear over a certain amout of frames you can set key frames in the visibilty track in the dope sheet editor. Hit f1 while in max and look up visibilty track in the help file. I am pretty sure it will walk you through the process. I hope this is what you are trying to accomplish.

[schmoron13]

thanks digtlpete, but actually, i don't want the object to dissapear over time, rather I want the bottom of the object to appear like it's continuing endlessly, and the best way is to probably gradually fade out the bottom...

[digtlpete]

Sorry, my firewall was not letting me see the images. Now that I can see them, my comment was a little off base.