Photons artifacts

[ediris]

Ok i have taken a modeled form my the previous city exported to OBJ and imported into EIAS via Transporter. Some pieces are missing but...
The problem i see besides a lot of shadow errors is that soft shadows with the GI engine totally avoids raytracing of the surface, being the car reflective and yet i had to set a few lights to ignore and as secondary lights.
What is going here?Thanks,
Edgard

[arketype]

Hi Ed,

Enabling Soft shadows using the GI engine does not automatically use photons.
Shading of secondary points (like your reflections) still needs a light (or lights) with mode set to "secondary". (You should avoid turning on secondary rays in the GI dialog, as they impose a severe render time penalty).

If you enable photons from the light's photon tab, AND set the mode in this tab to "GI and Secondary" then the secondary points (RT reflections and RT transparency) will use the photon map for shading, which is very fast. As an additional benefit RT blurry reflections are extremely fast as well.

The tutorial for "hidden light objects" walks through the complete process of setting up photons in a step by step manner. (You can ignore the setup of the hidden light dome if you place the car into an enclosed box).

Dave

[ediris]

Hi Ed,

Enabling Soft shadows using the GI engine does not automatically use photons.
Shading of secondary points (like your reflections) still needs a light (or lights) with mode set to "secondary". (You should avoid turning on secondary rays in the GI dialog, as they impose a severe render time penalty).

If you enable photons from the light's photon tab, AND set the mode in this tab to "GI and Secondary" then the secondary points (RT reflections and RT transparency) will use the photon map for shading, which is very fast. As an additional benefit RT blurry reflections are extremely fast as well.

The tutorial for "hidden light objects" walks through the complete process of setting up photons in a step by step manner. (You can ignore the setup of the hidden light dome if you place the car into an enclosed box).
Dave


Thanks Dave for replying,
I have photons activated to use GI and secondary rays.
In the dialog box i havent used a secondary rays, it will be of not use as this control how intensive is the shadow or if it has some artifacts.
None of these has been in my way.
I have one radial light with quadratic dropoff enough to cover the entire car. i have these light with soft edge and high specs to soften the shadows, photons are activated to use GI engine and the secondary rays.
Maybe with area shadows but not with radial lights.
Whenever i turn off soft edge it will cast RT reflections/refractions but otherwise doesnt seem to work for me.
Thanks,
Edgard

[ediris]

Well it seems that Photons cant cast RT reflections with one light only.You have to set one for GI only and another as a secondary.
Doesnt matter what type of light you use tired area,radial and spots.
In the other hand i am amazed by how fast soft shadows turned out to be thanks to the GI engine too bad RT reflections are not working for me.
Is a bit silly to use an HDRI when you can add some luminosity planes.
Thanks,
Edgard

[FrankyCh]

Hi Edgar,
does your scene have something to reflect?
If you look at the front bumper of the car, you can see it actually shows the reflection of the "radiator".
Are you using global reflection maps for the windows and other chrome parts?

Cheers
Francois

[ediris]

Hi Edgar,
does your scene have something to reflect?
If you look at the front bumper of the car, you can see it actually shows the reflection of the "radiator".
Are you using global reflection maps for the windows and other chrome parts?

Cheers
Francois
Hi Francois,
Does it has something to reflect? No but these is a second light that added to act as a RT reflection set up as a secondary lights.
I have tried it with soft edge and no photons/GI engine and it does work but when i activate the GI/photons it doesnt.
I mean soft shadows works very nice with Photons/GI, i did apply to my light GI and secondary rays on the photons dialog by the way.
I dont want to place an HDRI as a global reflection if i need to yeah, and i dont want to place a bitmap to reflect i just want RT reflections.
Than i can add a bit of a bitmap and maybe some HDRI reflection but i want to start from zero.
Thanks for the reply,
Edgard


edit : i will be very happy if Photons and RTReflections could work with one light.
I will not feel the need to get Vray , can somebody please send me an scene with one light emitting photons and RT reflections.
Thanks,Edgard

[ediris]

Hi Ed,

Enabling Soft shadows using the GI engine does not automatically use photons.
Shading of secondary points (like your reflections) still needs a light (or lights) with mode set to "secondary". (You should avoid turning on secondary rays in the GI dialog, as they impose a severe render time penalty).

If you enable photons from the light's photon tab, AND set the mode in this tab to "GI and Secondary" then the secondary points (RT reflections and RT transparency) will use the photon map for shading, which is very fast. As an additional benefit RT blurry reflections are extremely fast as well.

The tutorial for "hidden light objects" walks through the complete process of setting up photons in a step by step manner. (You can ignore the setup of the hidden light dome if you place the car into an enclosed box).
Dave
I finally found the culprit, SOFT EDGE whenever i activate it with light radius 0/ samples whatever number the reflections RT reflections will show but when i increment the sampling number above 1 they disappear. The photons are set to GI and secondary and the GI engine is emitting primary rays with no secondary rays as explained before.
What am i doing wrong?
Dont know but is driving me crazy!! :)
Thanks, Edgard

[atlantis23]

Hi ediris

It should work. Here's an example scene similar to your setup using soft shadow, photon map, and RT reflections.

http://www.atlantis23.com/pmtest.zip

[ediris]

Hi ediris

It should work. Here's an example scene similar to your setup using soft shadow, photon map, and RT reflections.

http://www.atlantis23.com/pmtest.zip
Thanks so much atlantis that was very helpful. Really loving the new feautures i just cant seem to understand how important is the to set the right amount of photons,the database, and more important than anything the distance ref% that is the main key here.
But i will read more into the manual i think that is the first place i need to re visit.
Thanks,
Edgard.
edit: Not sure if i can compare the renders to Vray physical camera.

[atlantis23]

You're welcome.

My workflow to find the number of emitted photons:
1. Enable Quadratic Dropoff as recommended for photon maps. Choose a reasonable Dropoff Control Distance.
2. The Dropoff Control Distance is automatically used as photon map Control Dist.
3. In the Photons tab, make sure the Control Dist is also the Density Diagnosis Distance. Lock the Density Diagnosis Distance box.
4. Choose lookup radii. GI radius 2 is recommended.
5. In the Database Options, choose the Segment Length. Segment length should be at maximum twice the lookup radius. For radius 2 choose segment length 2-4.
6. Enter a number of emitted photons. Watch the Photons value in the Density Diagnosis. The value should be at least 200-250. Increase the number of emitted photons until the photons count in Density diagnosis is 200-250. If your shadows look too grainy, increase the number of emitted photons.

For soft shadows (using the GI sampling engine), the primary GI ray count should be at least 250. 400 rays is a good value for smooth shadows. The GI Color Tolerance should be at least 2. The default soft shadows samples count 12 is usually ok. If you use a very large light radius or your shadows show fuzzy edges, turn off the Optimize option and increase the samples.

[ediris]

Hey is working pretty nice, one thing i havent figure is how much photons do i need to emit on the emission dialog.Other than that is fine for now.
Thanks guys.
Here i did a test with 100 Photons and with 10.000 photons.
Thanks,
Edgard

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