A small test with photon map

[hughg]

Goncalo thank you very much for posting your tips \advice and scene setup, but I am still trying to figure it out and Jesus me I am still lost......

Your point
4-With the all lights on, calculate the photon map only with the convert to irradiance map checked;

do you mean all the below lights that in the scene
1. Direct01
2. SunVRayLight03
3. And two VRayLights
because in your scene the SunVRayLight03 is off and it is in the same position as the Direct01 light. Are you using both of them or just the one. When you have the time can you clarify this, realise you are busy...

Thanks in Advance

Hugh

[GoncaloP]

No, only use the standart direct light as Sun, and the others two vray lights as skylight portals

Gonçalo

[hughg]

More the power to ya! Gonçalo
Thanks
Hugh

[PitFreedman]

I wonder how do you manage to read 5000 photons on Direct Light and 1800 on VrayLight? Even with the empty scene, Max on my machine crashes after reaching 98% of the tracing of the second VrayLight(2500 photons).It is still possible to read the first VrayLight but when it starts to read the second one, it significantly slows down and then simply crashes. At the same time the chart in Task Manager reaches 1.3GB. I can’t even read the scene in GhonsaloP http://www.gprospero.com/vray/tests/Small-room200-a.zip.

 Here is the configuration of my PC:

PIV, Xeon 3Ghz Dual
2Gb memory (4x512mbKingston)
WindowsXP Pro
SP1 3Dmax 5.1
Vray Adv 1.09.03n

I tried to play with Page File, restarted the HyperTrading, even added 1GB of the memory ( originally it was only 1GB). It still doesn’t work. Please let me know how I can fix it.

Thanks!

[GoncaloP]

Sorry but I had a mistake in photon map settings, I ve explain it but that is you need to change the max density to 1.0 and search dist to 5.0

Try to use the default unit settings, in this way it will work, your system is stronger than mine

Gonçalo

[didjaja]

Hi GoncaloP,thanks for this great tutorial
Some questions
You say some time "the result of the distribution from one vray light should be equal to the standart light used as Sun" and "you need to have the same smoth look,but not the same amount of light"
Can you post an easy example to understand that?
And what mean "convex hull area estimate" in the parameters?
Very very thanks in advance

[GoncaloP]

To see what I mean, the best thing is to check photon map for first and second diffuse bounces and then trace photons only for one light, in this way you will see the contribution of each one.

If the solution gets very dark, you can increase the photon multiplier to be alble to see what is happen, but for the final image, better to keep this at default 1.0

Gonçalo

[didjaja]

Well,i try but i dont understand "the result of the distribution from one vray light should be equal to the standart light used as Sun"
This mean than the contrast of bright and shadows of the photons are similar?I dont know
I have done this scene and this is an example of equal distribution of lights
Is this right? or this is erroneus



Very thanks
My settings:
Vraylights Multiplier 1.0(intensity,not difuse multiplier) Difuse subdivs 500
Direct Sun Multiplier 2.0(intensity,not difuse multiplier) Difuse subdivs 2000
Bounces 20
Max density 1.0 and search dist 5.0
Convert to irradiance on 20 inter samples
Treshold 0.0
Retrace bounces 20

[GoncaloP]

It seems right, but probably I would trace even more photons. Try to check it with irradiance map for first diffuse bounces, if you get good results its ok, but if not just increase the number of subdivisions.

Remember that:

1000 subdivisons > 1.000x1.000= 1.000.000 photons
2000 subdivisons > 2.000x2.000= 4.000.000 photons

The small bright dots you can see in your images, means that you need more subdivisions

Gonçalo

[didjaja]

Very thanks Goncalo
This is the final image with irradiance map in the first bounce
11min rendertime
Some adjust of levels and noise added in photoshop
For the moment its ok for me
Very thanks,i learn very much with you
Thanks

[GoncaloP]

Very nice

[metroberlin]

photons are the users best friend !!!!

[didjaja]

More questions
How can increase the global secundary ilumination with photons?
I put 70 bounces and i see a little more ilumination,but only a little
I change to direct in secundary bounces and i put 4 in deph and the ilumination is very very strong and the time is less
What can i do? Increase the multiplier of bounces?
I render without bounces (None in secundary bounces)and the image is a little dark but is very similar that global photon map 70 bounces,the change isnt strong
I dont understand,please help me
Thanks

[GoncaloP]

To get a higher secondary illumination with photons you can increase the the multiplier of the secondary bounces, but if you want to keep the contrast better to play with color mapping increasing the dark multiplier. There you can find three types, linear exponential or HSV exponential.

Gonçalo

[didjaja]

Yes I know but
Why with the same parameters in all (multiplier of secundary bounces,color mapping,enviroment....)with direct in secundary bounces and only 4 in deph the image is very much iluminated than with 70 bounces in global photon map?
And with direct is faster,why?
Why i need increase the color mapping and the multiplier of secundary bounces working with photons and i dont need working with direct?
Very thanks for your time GoncaloP