Qustion About Background In Animation

[mike_w]

[b]I have Maya 6.5 and PhotoShop 7.0. I'm creating an animation sequence of a ship sailing along. Very simple actually. To use a sheet as a backdrop with a sky texture doesn't look too good. Maya recommends I use the default black background, batch render the animation then go in and, frame-by-frame, substitute the sky texture for the black. Great but in PhotoShop you have to select the black then reverse select and insert the ship/ocean into the sky texture. That's fine except in PhotoShop its all guess work.

The bottom line is what do you experts do to handle the background on out of doors animation?

Mike_w [/b]

[joojaa]

QUOTE(mike_w @ 10/25/07, 12:32 AM) [snapback]275382[/snapback]
Great but in PhotoShop you have to select the black then reverse select and insert the ship/ocean into the sky texture. That's fine except in PhotoShop its all guess work.

Thats why the renderer outputs alpha. And really theres no guesswork, the black is just transparent. But see photoshop isnt really the tool for animation comp.

[adam-clear]

Mike - There's really two ways to pull it off.

You can create an image plane that will render. The image plane would be stuck to the camera so it would always be in view. This really only works well if it's a static shot. If it's moving footage (image sequence) then you have 'matching' you might have to do in something like Maya Live or MatchMover to align camera moves.

The better choice is to render an image sequence of your 3D element with an alpha and composite it with your background in something like After Effects. You can learn more about it at this link. While Lightwave is used in the example the ideas are the same. You can find more about the proper execution with Maya in the 'Help' files.

Good luck.

[dryodryo]

For a background sky you can also do the following (assuming Maya Software renderer). This will allow you to use a moving camera without any compositing.

Create a large sphere-- just large enough to enclose your scene. This is your sky dome. If you wish, you can scale the sphere down in world Y to produce a flattened dome.

Assign a Surface shader to the sphere. Drop your sky texture into the Color attribute. The texture will have to be very high resolution for this to work well. You may also have to assign a UV projection to get the texture placement right.

Point Constrain the sphere to the camera. Now when you rotate the camera, the background changes. But when you move the camera, the background does not change. This simulates a backdrop at an infinite distance.

You may need to increase the Far Clip attribute of the camera.

[mike_w]

Thanks for the tips. Since I have several ships, islands, etc, I'll create one ocean/sky and rotate the objects in and out of the scene. Great thanks.

Just two little questions. On Global Render choices Mental Ray doesn't show up as a choice. What have I done wrong so it won't show? It was and is loaded. Also, for smoke to emit from a ships smoke stack I click the flat piece on top of the stack as the emitter. It creates a circle emitter. How can I change it to come more out of the center?

Mike_w

[dryodryo]

For your smokestack, just create a Volume emitter (cylindrical) and parent it to the ship. Don't use Emit from Object in this case.

[mike_w]

Thank you DrYo, you have been right on and very helpful. One more question. I've created my sphere for the background and assigned a sky texture to it. However there's an obvious vertical seam line in the sky. Got any ideas on how to I fix this?

[dryodryo]

You can adjust the U or V Offset attributes in the 2D Texture placement node, and that will move the seam somewhere else. Use fractional values like 0.2 or 0.4... if the Offset is 1.0, it just wraps back to where it started.

If you need a sky that is totally seamless, you'll need a very high resolution image, and it will need to be tileable. The quick way to create a tileable texture is to use the Offset filter in Photoshop and paint over the seam.

Creating seamless textures for a spherical projection is a bit tricky. But you can use the Polar Coordinates filter in Photoshop. That will remap the image so that it "fits" properly on a hemisphere. But this still might not give the results you desire.

Another way to approach this is to drop a Ramp texture on the skydome; this will get a colored gradient for the background. Then create clouds separately. You can make semi-transparent textures and place them on planes floating in the scene above the ground plane but below the skydome. Or, you can use particles or fluids to build the clouds. That gives the advantage of the clouds responding properly to light, and since they're volumetric, you can even fly through them.

[mike_w]

[b]Thanks for the advice DrYo and others. This is the best help I've had at any 3D graphics site. I feel that a number of the sites can't be bothered with newbie scum, after all they are the "professionals."

Anyway, I created a sky dome and attached a Photoshop .bmp of a blue/gray sky gradient. To avoid the seam problem I turned the image sideways - hey it worked! I did as instructed and created an emitter and attached it to the center of the ship's funnel. I then attached cloud texture to it and darkened it. When I play animation little particles emit like they're supposed to. Yet, when I render I see nothing. See attached links. I don't want to use a smoke sprite as that has to be hardware rendered and the ocean isn't visible for hardware render.

Mike_w[/b]

http://img.photobucket.com/albums/v713/mik...HEIANPIC-17.jpg
http://img.photobucket.com/albums/v713/mik...HEIANPIC-11.jpg

[dryodryo]

Are you sure you chose Cloud as your particle type and assigned a Particle Cloud shader?