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Dangertaz
05-20-2009, 04:07 AM
I'd like to use the photo lens and rayswitch advanced together with physical sun+sky as described here at the top....

https://www.blogger.com/comment.g?blogID=36992715&postID=4256118424571007843

I plug everything in as he describes: lookup_spherical plugs into default channel on rayswitch advanced, sky plugs into rayswitch final gather channel. Rayswitch advanced is then plugged into the camera's mental ray environment channel. The objects are lit correctly by the sun but the background is BLACK. I then connect an exposure simple lens and the background appears although its very dark and I'd like to change the orientation of the HDRI.

So...

How can I get the photo lens shader to "see" my HDRI/jpeg in my rayswitch default channel and is there a way to move it?


Anybody have a better/simpler approach to using Sun+sky with a different background for reflections?


Many thanks in advance!

royter
05-20-2009, 04:26 AM
try linking it to the env. port of your physical_sky node.

Dangertaz
05-20-2009, 04:25 PM
I can see the background without the photo lens but I like to use tone mapping, so it's kind of a "must"...

Anybody?

Dangertaz
05-21-2009, 12:29 AM
I tested the set up again and with a simple exposure node the backgorund appears, although its a tad dark. With photo exposure, I have to crank up the iso values extremely high (or lower the f stops, shutter speed) to see the background, but it is there. Unfortunately this blows out any geometry in the scene, as my jpg shows.

Is there a way to increase the color gain on an mib_lookup_spherical node? Something to brighten it up so the photo lens can have reasonable settings and still see the HDRI background?


Any help would be fantastic!

igi
05-21-2009, 12:11 PM
I think this is answer to your question

http://mentalraytips.blogspot.com/2008_02_01_archive.html

ytsejam1976
05-21-2009, 04:25 PM
Your background needs a multiply node from spherical and background. Set up the value of your multiply over 8000-8000-8000


I hope that i know what do you talk. :)

royter
05-21-2009, 07:27 PM
I think this is answer to your question

http://mentalraytips.blogspot.com/2008_02_01_archive.html

I have read Zap's whole article ( and the 2 others related to it).
I understood the whole problem and what's causing it.
basicly the mia_exposure_photographic not "affecting" the background image wich turns out black due to weak luminance.
But the solution is a bit MAX specific. I would really like to know the solution in Maya.

Dangertaz
05-21-2009, 08:52 PM
Is there a way to fix this in Maya?

igi
05-22-2009, 10:48 AM
Solution is to crank up your color gain value in texture node to few thousand (similar to what ytsejam1976 said).

Dangertaz
05-22-2009, 04:22 PM
With a maya surface shader it's easy, or with an Mia material, you can simply plug a gamma correct node into the diffuse color and control brightness that way.


But mib_lookup_spherical grabs a texture, but that texture doesn't have a diffuse or a color or anything that seems like a gamma correct node or a multiply/divide node could connect to.
I've included a screenshot of what the connection editor sees with I drop the multiply/divide into the texture of the lookup_spherical, how specifically do these two nodes work together to increase brightness?

Maybe the mental ray environements aren't the way to go for this?

Thanks for all of your suggestions so far! :)

ytsejam1976
05-22-2009, 04:45 PM
no.
You simply drag the spherical lookup node into input 1 of multiply divide. In bachground of phisical sky, insert the multiply divide and after this set the multiplydivide input 2 to 5000-5000-5000 and over.

royter
05-22-2009, 05:17 PM
5000-5000-5000 and over.
is there a reason for using that exact number?

ytsejam1976
05-22-2009, 06:32 PM
is there a reason for using that exact number?

Oh no, never reason, but for see the image on spherical lookup, with exposure photografic, the way is this. :)

Dangertaz
05-23-2009, 05:50 PM
Sorry about all the questions, this was the solution!

Thanks again!

royter
05-23-2009, 05:58 PM
Oh no, never reason, but for see the image on spherical lookup, with exposure photografic, the way is this. :)

hmm... seems to mee like a blind guess.
usually i like to know what i am doing and i don't like exceptions.
but if it works than why not.

ytsejam1976
05-23-2009, 11:06 PM
No problem Dangertaz. :)

royterr, in ever my tests i have the full control of any situation.
You know that the rgb unit conversion, is to set the multiply in a more simply control. But if you set the rgb to 0.000000 the multiplier of sky is in lux, like 80000, 127000 or 0.07 in a moon light. If you use exposure simple, the cntrol of the multiplydivide is set in more cases on 3, but in the exposure photo, for the conversion factor, we must set the multiplydivide input2 more up and up and up.

In this time i'm busy for tests, but in future, i know the results, thechnically. :buttrock:
Bye bye and good work

Dangertaz
05-24-2009, 03:29 PM
So you could set the RGB conversion on the physical sky to 000000 to convert it to lux and then in your multiply/divide give it a value of .07 (lux?) when using a simple exposure? I always wondered about physically accurate moonlight....

Thanks again!

ytsejam1976
05-24-2009, 03:30 PM
No, in the multiplier of the phisical sky, but some test reports the value on 0.100. Is more various about the exposure shutter speed and ISO.


0.01 lux Quarter moon

0.27 lux Full moon on a clear night

1 lux Full moon overhead at tropical

igi
05-25-2009, 08:58 AM
thx ytsejam1976, good to know :cool:

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