Strange Problem With Ocean Shader

[f3de]

I have an ocean scene with a large zoom from very far to very close, when I'm close to the ocean I need an high detail(many more polygons) so I have 4 different ocean planes with different size to but only the first (the big one) seems to render correctly. I explain: with the other ocean planes when rendering with mayaSW I noticed a strange cut of polygons, it's not the clipping plane of camera 'cause other objects render perfect,I noticed also scaling a bit or moving on Y the plane change the cut. It seems depending on the eigth of polygon like an orizzontal plane cutting the ocean. with mental ray there's no problem, but the ocean seems rendered best with mayasw.
here two sample image to undertand better

[duncanbrinsmead]

There is a bug where Maya displacements use the 2d view clip of the non-displaced ocean plane, which can result in problems with large displacements when the plane is viewed exactly edge on. A workaround for this is to make the the ocean plane geometry slightly non-flat. (not sure if this is your problem though) Also try and keep your far and near clip as tight as you can... for large scale scenes the near clip needs to be suitably large. Make sure that on your geometry "feature based displacement" is off.

Note that there is an attach to camera option on the create ocean menu. This will attach the ocean plane to the camera(using an expression) such that the most triangles are concentrated where the camera is looking. The plane automatically scales up when the camera goes up in Y, and tracks the camera in XZ. This allows one to fly the camera anywhere over the virtual ocean surface and never run out of ocean. One can animate the camera up into orbit, or get close in, next to the waves.

Duncan

[f3de]

tanks for your reply, I not understand well what do you mean for make the plane slightly non-flat. i must rotate a bit the plane or I have to modify the nurbs plane? what I have to do?
I've tried also the "attach camera" but when the camera zoom I noticed a lot of flickering of polygons, maybe it's caused by a low number of polygons?

[duncanbrinsmead]

QUOTE(f3de @ 02/27/06, 01:51 AM) [snapback]229382[/snapback]
tanks for your reply, I not understand well what do you mean for make the plane slightly non-flat. i must rotate a bit the plane or I have to modify the nurbs plane? what I have to do?
I've tried also the "attach camera" but when the camera zoom I noticed a lot of flickering of polygons, maybe it's caused by a low number of polygons?

With the attach to camera you may need to increase the render tessellation levels on the ocean to avoid flickering when the camera moves(basically the triangles are flowing over the displacement... the profile may wiggle a bit , although the bump shading should stay pretty consistent, at least with the Maya renderer).

You are probably not hitting that clip problem, but at any rate you could try displacing a cv or 2 of the ocean surface in y a little.

You might also try setting the boundingBoxScale (under "displacement map") on the ocean shape node to a large value by hand. (though I doubt this will help)

Duncan

[f3de]

i've reduced the length of big wave and it seems to work..... I've the boat, I've tried the nurbspreviewplane to create a curve to emit splashes....but now how can I create foam from the boat?

[duncanbrinsmead]

For foam you can use the ocean->wake feature. It creates both a wake displacement texture and a foam texture. If you make the wake intensity zero in the options and have some foam intensity it should only create the foam fluid if that is what you want. You can add multiple emitters to the foam fluid an parent to your boat, or emit directly from the boat hull into the fluid. (fluid->emit from object).

Duncan