[Steve Bentley]

I think I get it – you want to put something abstract within the water shapes right?

Couple of things off the top – that wide shot of the fountain should indeed have an alpha from the stock company – you’re right that’s what the checkerboard means – they usually don’t supply the alpha in the low rez temp version just to save bandwidth. However, I don’t think the alpha has been done properly. It should have some parts within the water that are blocking the alpha and other clear parts that let the background through – I only see alpha outside the body of the water. That shot looks like a CG shot that’s just had an “outside alpha” rendered. So you could use that element to mask your abstract but it would be a fountain silhouette and would not look like the abstract is being distorted by the water. If that’s the look you are after you are home free.

As for a luma or color key on the other water element, this can work but remember that while it keys out the black (or uses the black as a mask) it can also key out black “reflections” and distortions in the water itself that may be meant to be opaque. It can work if you don’t look too close but often it just doesn’t feel right.

Depending on the background you can often “screen” or “multiply “(the blend modes) the water on top and then use a distortion or displacement filter to warp the image being masked by the water. This is often a good enough illusion because parts of the water will step on the abstract and the background depending if they are brighter or darker. Water is usually clear but it usually isn’t showing what’s right behind it through the clear parts and when it does the background is distorted by the water drops. And you should be getting some specular highlights and reflections that will obliterate what you can see through it. Keep in mind, any added hilights should be “screen”ed on top so that any thing brighter behind will still penetrate through just the way real light works.

So the layer order would be from bottom to top.
Background, abstract art passing through a track matte of the water alpha, then the water again either screened or multiplied on top. For extra points you could add a displacement filter to the abstract, using the water element as the displacing layer and then mask all of that with the water alpha to contain the distortion, and that will give the abstract some refraction effects. You could also try the glass distortion effect or Mr Mercury effect (if its still around), compound blur might do the trick too if you use a blurred version of the water as the distorting element in that effect.

[Steve Bentley]

You should be able to get there in AE. Pshop and AE are very similar – Pshop got its layering system from AE but alas AE has yet to get its paint from Pshop (how long have we been waiting?).

Anyway – the only real difference is in the track mattes in AE and the precomps instead of folders.
To use the track mattes, a masking layer sits on top of the layer you want to mask. The track matte layer becomes the mask (and is usually turned off) and you can choose either to use the trackmatte layer’s alpha or its luma levels if it doesn’t have an alpha. You can reverse the masking as well.
Depending on what version of AE you have you may not have any folders to work with. (so that you can pass blend functions through from whats inside the folder). To do this in AE you may have to precomp the layers in question. That precomp becomes a single layer in the outer most comp, and that precomp gets rendered before it gets layed on top of the rest of the layers in the outer most comp (AE is more like Illustrator in this way). The problem is any blend function you use on the precomp in the outer comp is on the full render of the precomp. And any blend function you use inside the precomp is only good inside that precomp and doesn’t always work if that precomp is on nothing because you are trying to keep your matte (“Screen” for example doesn’t work properly if there is no background to screen onto).

What might be best is, to have a go at it in AE and then post the project and we can have a look and suggest a way to organize it so it does what you want.

With the exception of some fx that might not be in AE, that you do have in pshop, all should be doable. Even things like running the dodge tool along a path can be done in AE but in a different way (the path becomes a mask that you apply a levels filter through)

[Steve Bentley]

When you say playback in real time do you mean once its cached? Have you checked the memory allocation in the preferences? What video card are you using and is Open GL turned on or off? How about Mercury transit? How many monitors? Whats the stage size and frame rate you are trying to hit?

[Steve Bentley]

Think of the white in either the image (for luma mattes) or the alpha (for alpha mattes) in the layer that is acting as the track matte as a window the video below can shine through. If you pick alpha matte whatever is white in the alpha of the track matte layer (not the layer below it) will act as a window and “project” that lower layer on top of all the layers stacked up to that point. If the lower layer has an alpha too, it will combine with the track matte layer’s alpha – so a white circle in the alpha of the track matte layer will combine with a white square in the lower layer’s alpha (the layer that is “passing through” the track matte layer) to create a circle cut off by some straight sides and tops (assuming he square is only a little smaller than the circle).
The same goes for the luma matte option except the track matte takes the grayscale levels in the RGB channels of the trackmatte layers and uses those as the window.
You can do all this with the inverse – so in a sense the black in the track matte layer becomes the window. That’s why there are 4 choices in the track matte drop down.

Be careful too that you don’t double matte your photoshop elements. If you have white text on black in the RGB channel and then use that same white text in the alpha channel to act as a cookie cutter for the RGB channel, you are really masking that image twice: once with the alpha and once with the black edges encroaching on the white text through it’s antialiasing. If you want clean text or any other shape, make sure the edge of the RGB elements bleed over the edges of where the alpha element falls. (or just fill the RGB with solid color and let the alpha be a cookie cutter).

You can also just make your text or graphic a layer in photoshop and then import the file as a photoshop file into AE and choose that layer to be your artwork. It will self matte when its a layer. You can also use it as a track matte to pass lower layers through the area where the artwork is – there is an implied alpha with a photoshop layer.

Remember too that when you crush levels or curves to make an alpha channel out of something that might not have been black-and-white enough to be alpha, you will often get ratty edges as the nice smooth roll off of the antialiasing gets crushed in the levels filter.

[Steve Bentley]

Keep in mind too things like luminence with a fresnel can be really cool but often it won’t show if the object is 100% transparent. Try bringing your white (the transparency amount) down to a 95 % gray and see if that helps.
There’s also a couple of shaders in the legacy “extra” bundle that you can combine with transparency. Do a search for Danel or Mabel in the content browser and that will reveal where they are stored. (its not those two but I don’t recall the shader’s name, but it was part of the pack that included the two above)

[Steve Bentley]

Thanks Brian, you’re right of course. I just have so many hairs in that one poly they are busting at the seams. Using a circle gradient in the density tab of the shader helped with that but that brought up a new problem. There is no spatial mapping setting for the gradient in the density tab (its grayed out – in what circumstances would it be available?). And I can’t quite figure out the mapping.
If I set a plane to 9 divisions (3×3) and use the center poly to emit the hair, applying a gradient (in density) to that seems to map the gradient to the whole plane, using only a small fraction of the gradient for the center poly – that made sense. So I thought, hey if I delete the unemitting polys the gradient will map to just that one poly. Not so much.
So how does one determine what expanse the texture you are using to set where hairs aren’t can stretch over? For a sphere for instance what mapping routine is used for that density “texture”?
Is there a way to apply the texture (in my case a gradient) to another object that will set the spatial nature of the map, and then point the density tab to that material on the other object like you would with a mograph shader effector (I mean I’ve always believed all of these cool toys are all based on the same system given the cloning nature of them).
And now that I’ve written that, I’m off to try a shader effector being use with the hair object. Mad Science! Frankenshader!

[Steve Bentley]

On closer inspection of your set up – you already have the spline to extrude from. Get rid of that loft object.
Close the spline (the one side of the shape) with the check box in the spline attributes, then put that closed spline under an extrude, make sure to check “Create single object” in the caps tab of the extrude object. Make sure the extrude direction/distance is in the Y only. Then put all of that under the symmetry object and make sure to check “weld points” in the symmetry object tab.

The other thing you can do with that kind of shape is tuck it under a cloth object. Then you can set the thickness. It often creates geometry that can be problematic but it is a sort of extrude.

The reason your solution doesn’t work is that the spline has a direction to it. When you use symmetry, the mirrored spline has the reverse direction so the two splines can’t be joined by the system in one long continuous spline for extruding. Try it – use the spline on the one side and put it in a symmetry object, and then close that original spline with the check box. The end of the original spline will join to the start of itself and so will its mirror spline. So you actually still have two shapes in there. Unfortunately once you make the symmetry object editable you can’t disconnect those splines, reverse one and then join them (which is what you would normally do when closing one spline with another). To join two splines they must be going the same direction. The tail of one joins up to the start of the other (you can tell the direction because they start out white and then fade to blue at the tail.)

[Steve Bentley]

Here’s a project of the steps I mentioned. Don’t forget to change the caps on the extrude to triangles or you will have bad geometry.

13797_extrudingaloft.c4d.zip

[Steve Bentley]

It really depends on what the loft shape looks like and what you are trying to achieve. The idea with an extrude is that it takes the boundary shape and makes those the “walls” of a new taller object. With a loft, often there are lots of polys on the “top” surface.
What you could do though is select all the perimeter edges and then choose “edges to splines” and then extrude that spline. You will probably have to triangulate after that so you don’t get bent polys (assuming the resulting spline is no co-planar).

[Steve Bentley]

Thanks Brian,
I figured that about the selection filling. Too bad the interactive preview doesn’t reflect that.
But doesn’t that mean that, given the hair will fill each poly in the selection (by the time you get a thick enough forest of hair), we’re getting hair plugs?