G.i. Workflow In Mantra

[kubabuk]

How about storing the path to you file in a global variable. This way you can easily update a map wherever it is used.

[wreath]

Yes it's an option but it should be a way to set it for all scene

[stu]

There is, and that's the way.

[wreath]

ok another question (99997 left ) how can i render my backround image? it's better to combine them in compositing but sometimes it's handy to see the backround image in render. By the way this topic becoming a nice reference for basic rendering stuff thanks for all your help but it would be better if someone ask questions except me i'm feeling weird a little.(the only guy who trying to learn rendering on earth)

[zasid]

ok another question (99997 left ) how can i render my backround image? it's better to combine them in compositing but sometimes it's handy to see the backround image in render. By the way this topic becoming a nice reference for basic rendering stuff thanks for all your help but it would be better if someone ask questions except me i'm feeling weird a little.(the only guy who trying to learn rendering on earth)

When you see your render in the Mplay do these steps .

1:Press d

2:goto the Background tab

3:and from there load ur background in the scene

If you want to see ur background in the view port follow the same steps .

Hope it helps.

[wreath]

When you see your render in the Mplay do these steps .

1:Press d

2:goto the Background tab

3:and from there load ur background in the scene

If you want to see ur background in the view port follow the same steps .

Hope it helps.

Yes i'm using it too but can't see in render, only viewport.

[wreath]

Found it; mplay window(render window) > windows > display options > backround

[Netvudu]

Don

[symek]

ok another question (99997 left ) how can i render my backround image? it's better to combine them in compositing but sometimes it's handy to see the backround image in render. By the way this topic becoming a nice reference for basic rendering stuff thanks for all your help but it would be better if someone ask questions except me i'm feeling weird a little.(the only guy who trying to learn rendering on earth)

If you're really after rendering with background, what is bad idea as you know, but lets assume you need it badly, you can always use fog shader to add it. The simplest code follows:

fog
bk(string map = "")
{
	vector ndcP = toNDC(P);
	Cf = lerp(Cf, texture(map, ndcP.x, ndcP.y), (1-Af));

}

cheers,

sy.

[Krakatuk]

Hi! Can someone tell me, why could it be so - when I render with just v_gilight, picture is clear, when I put a RAT map into environment, it becomes grainy. And can maps generated with isixpack be more than 256x256?

Edited March 20, 2008 by Krakatuk

[symek]

Surly they can be bigger, I've never heard about any limitations here. However the smaller environment map helps you deal with grainy look since the less differences in samples form a map means the less noise in occlusion. Rays in occlusion are scattered randomly across the hemisphere, they hit your texture and returns its colour. In bigger, not pre-blured images there are far too many pixels variations found by these rays, so image gets grainy. See the sky, the colour of it it's quite constant, isn't it? Clear gradient. That's why it's worth to keep your environmental maps small and/or blur it - with build-in filtering option in texture() or before rendering.

Did you turn on Irradiance cache? (Mantra ROP -> Properties -> Irradiance Cache) This will speed up your render + will help with a grainy look since thanks to cache Mantra interpolates colour samples across the surface == remove grain.

HTH.

sy.

Edited March 20, 2008 by SYmek

[Krakatuk]

Surly they can be bigger, I've never heard about any limitations here. However the smaller environment map helps you deal with grainy look since the less differences in samples form a map means the less noise in occlusion. Rays in occlusion are scattered randomly across the hemisphere, they hit your texture and returns its colour. In bigger, not pre-blured images there are far too many pixels variations found by these rays, so image gets grainy. See the sky, the colour of it it's quite constant, isn't it? Clear gradient. That's why it's worth to keep your environmental maps small and/or blur it - with build-in filtering option in texture() or before rendering.

Did you turn on Irradiance cache? (Mantra ROP -> Properties -> Irradiance Cache) This will speed up your render + will help with a grainy look since thanks to cache Mantra interpolates colour samples across the surface == remove grain.

HTH.

sy.

Thanks, but I truly still don't get it, how to render it with hdri but not so dirty. Here are pix and the scene. The dirty pic - rendered with v_gilight and env map.

testScene.rar

[Krakatuk]

Hmmm... when I use RATs from $HFS/houdini/pic/ - pic's clear too... But I converted hdr cross into rat by use of "isixpack file.hdr file.rat". What's wrong?

Edited March 21, 2008 by Krakatuk

[Krakatuk]

And when I use isixpack the output image is only 256*256, when I try with something like "-u 512 -v 512" - it is only 256*256. I don't get it.

Edited March 21, 2008 by Krakatuk

[stevenong]

Hi,

What isixpack is doing is to create 6 images: Right, Left, Top, Bottom, Front and Back. Basically, it makes a cube with an image on each face.

Try this: mplay myimage.rat & when mplay is opened, you'll notice there is a pull down button with the "Right" on it. Click on it & you'll get the other planes.

In the CreatingReflectionMaps wiki page, you'll notice the sphere in the first reflecting a cube which is what isixpack is.

Last but not least, this online Help page has some useful tips: http://localhost:48626/light/ambientocclusion

Hope the above helps!

Cheers!

steven

[Krakatuk]

Hi,

What isixpack is doing is to create 6 images: Right, Left, Top, Bottom, Front and Back. Basically, it makes a cube with an image on each face.

Try this: mplay myimage.rat & when mplay is opened, you'll notice there is a pull down button with the "Right" on it. Click on it & you'll get the other planes.

In the CreatingReflectionMaps wiki page, you'll notice the sphere in the first reflecting a cube which is what isixpack is.

Last but not least, this online Help page has some useful tips: http://localhost:48626/light/ambientocclusion

Hope the above helps!

Cheers!

steven

Thanks, I've surely read about ambient occlusion and that's why I'm here, because there is only the most basic setup and not enough for me to figure it out. Also I noticed black lines in those places where one surface intersects with another.

And you can kill me, but I don't understand the workflow with hdri. Is there an usual way like in VRay, modo, Maxwell of using hdri, without uncertain manipulations.

[symek]

As I told you already, your envmap is not pre-blured, which makes your randers grainy. Have you checked Area Light / Environment Mode in standard Houdini light? It gives you pretty similar results as GI/AO solution with as much as two clicks

If you're convinced to GI/AO path:

As far as I know It's hard to pre-filter maps after conversion to isixpack cubic texture, this should be done before. But you can use "pixelblur" option of environment parameter in occlusion() VEX for a cost of little time in rendering (although recent Houdini builds seem to deal with render-time big filtering (+200pixels) pretty well perhaps due to a new mip-map usage).

Unfortunately standard VEX GL Light Shader doesn't support texture filtering so you're forced to write your own VEX. Not so difficult after all. I agree this should be bundled in Houdini in a much better way than currently. See attachment for a VEX code in GL Light custom shader.

HTH.

sy.

TestGI_skk.hipnc.zip

[Jason]

Also I noticed black lines in those places where one surface intersects with another.

This is due to RayBias.