is there a tutorial for creating radiosity type lighting from a point light source or using a constant shaded object as a light source as the help card doesnt have the link, its inactive.

or could someone tell me how i have to set this up? i need to light a room from a single lightsource.

cheers,

Mark

Hey Mark

I think u just add another light with a Vex Global Illumination shop in the light shading bit.

Set Vex Global to full irradiance. It should use you original light as source for bounced light
Also remember what Phil was saying about needing to create a phantom object to create bounced colour.

Cant really remember full details, i can check our notes if u want

Anyway, call later hehe

J

i cant get that to work , that still seems to be a background illumination technique, ie, an `external` scene.. when you have an enclosed space it occludes it. what i`m looking for is more like radiosity. could you have a flick through those notes and let me know if there is anything that looks like it might be this.

cheers.

ok dude - just got to pop out, ill check notes when i get back - have u tried setting the global tint up to something like 8?

normally u cant see it, and u have to adjust brightness, or global tint

i dont think the gi light does it.. well.. maybe it does.. but as far as the full irradience and AO go theyre environment lighting.. from an infinite hemisphere as far as i can tell.. i want radiosity.. from a specified point…

eg.. place a point light in a cg room.. it lights the room with all the light bounced around from that point.

dude - ive just put something together to demo what i mean…im sure it must be what u want. - i just dont know how to attach .hip files here!!! if someone could let me know

so i posted it on your thread on odforce:
http://odforce.net/forum/index.php?showtopic=3282&st=0&p=21851& [odforce.net]

when u get it..

Load up - and look through the cam.
Fire off a mantra.

The GI light dimmer is set to full - it should render as u want. if u set the GI light dimmer to zero it will not have bounced light

Let me know if im completely wrong here, as i am interested in what u are wanting to achieve.

Cheerth

J

I think you want Photon Mapping which will bounce photons around the room.

1. Create Photon shaders for each object. To start, set diffuse and specular each to .5 probability.

2. In the Mantra ROP turn on Generate Photon Map, specify a Global map, clear the Caustic map.

3. Create a Light object set to Realistic falloff, likely you have to crank Dimmer to 5 or so.

4. Set the Light mask in the Mantra ROP to only use this light.

5. render the Photon maps.

6. create another light that uses the GI Light shader, specify the photon map in the GI light shader.

7. Render using this one “normally” and there you go…

Cheers,

Peter B

Pbowmar - thats really cool - thanks, will give that a try myself.

Could you explain to me what is going on with the Vex GI then? My Radiosity/GI knowledge isnt the greatest in the world - but I do recall doing a SESI tutorial where I pointed a cone light through a simple box room with a window, and in order to create the bounced light in the room the Vex GI was all that was needed set to Full Irradiance (with global tint boosted), without the need to render photons as you mentioned.

This seemed to work fine, and the example I posted on odforce, seems (to me) to be doing something similar in a box room with a point light in the corner - ie, using the VEX GI to spread bounced light about the room.

I would really like to clarify what is going on.

If the Vex GI is environment based lighting as Mark mentions (ie an infinite hemishpere) how is it working in the example i posted which is a box with a point light in the corner?

Thanks, would really appreciate any tips

J

PS - you from Bournemouth?

Hey,
Irradiance is just a single bounce of light, photons will keep bouncing until they run out of energy. Basically, that's it… and yes, I'm in PG11 )

Cheers,

Peter B

ok - much clearer, thats really cool - thanks!

just need to ask a couple more things - sorry, its just so hard to get houdini info at the mo, and the tutorials i have (and i have all of them) only deal with photon mapping when it comes to caustics.

To keep on Marks topic - im a bit confused now as he mentioned that the Full Irradiance setting was a..

'background illumination technique, ie, an `external` scene.. when you have an enclosed space it occludes it'

I assume he is right, (normally is) as he also mentioned that it worked from an infinite hemisphere - which would also be logical - especially with Ambient Occlusion.

However, if irradiance is a single bounce of light - how is this working from an infinite hemisphere - and surely, even though there is only a single bounce of light, this is still radiosity - it is lighting from a single point isnt it?

Cheers

J

PS - PG 11 eh? shame, as Mark and I have just finished the MA - did u get to see our project on the 2005 reel?

hey pbowmar

this sounds like what i want.. but i still cant get it to work… followed you up to `and render this like normal` regarding the GI light..

i`m still just getting black.. do i need to have the global map read into the GI light in the photon maps tab.. i assumed i do.

also i assumed i need to render in a new mantra.

but i still get black.

it was easy in max *cries* (houdini is still better tho)

hey spaceboyzero,

i replied over at odforce so i could attach hip and image.. should get you going on photons..

http://odforce.net/forum/index.php?showtopic=3282 [odforce.net]

in regards to the ‘render like normal’, peter just meant to shoot off a normal mantra (image that is) as opposed your mantra rop rendering photons..

@sesi: any chance of attachments to posts? kinda liked it in the early access forums..

hey - deecue

thats really cool - thanks, today has cleared up so many of my own thoughts and questions

especially as there are no tutorials yet available on this functionality

Houdini being my first and only 3d package - sometimes its like flying blind with no prior experience to draw from

i hope SESI do sort that out soon as Houdini is such a great package

Cheers

J

deecue
@sesi: any chance of attachments to posts? kinda liked it in the early access forums..

Yeah, very useful.

jason_iversen

deecue
@sesi: any chance of attachments to posts? kinda liked it in the early access forums..

Yeah, very useful.

Your wish is my command!

catlee
Your wish is my command!

Can I get you to have a little word with my boss? :idea:

JohnnyBGoode
Houdini being my first and only 3d package - sometimes its like flying blind with no prior experience to draw from

thats not such a bad thing. my biggest problem when first learning was trying to think relative to how things are done in other apps

What Deecue said ) When I did the room radiosity tutorial I started out using the Photon stuff, but I was frustrated by the fact you could not “aim” the photons, and there is an upper limit of 2 billion or so (I believe an Integer 32bit limit or something?) so I had a hard time getting the detail I wanted. Then I ran out of time (

Cheers,
Peter B

there was a tutorial? :shock:

There's a video tut for the Irradiance stuff. It's here

http//sidefx.vislab.usyd.edu.au/houdini_video/by_topic/rendering/index.html

Cheers,

Peter B