HDRI light probe from interior scene with vraycam

[teabag]

Hello,

In former vray versions prior the ones with phys cam it was easy to make an HDRI probe render from an interior scene.

Now its impossible. the settings in render dialogue do not override the phys cam FOV...it renders the same and the result is nowhere near the angular map look it should have when u set the FOV in render dialogue to 360 (spherical cam)...

the only way would be nozt to use physcam, but thats not what i want to do really...

is there any workaround?

Thanx Martin

[studioDIM]

There's the dome camera to take probes.
I think the physcam should behave the way it does, as a standard lens would distort what you see (should it ever get to a 360degree viewing angle...) in pretty much the same way the physcam does .
I *think* i could cook up something to try and match an unexposed camera to a vray physcam, so that most of the exposure could be done through material darkening/GI demultiplication, and the switch to a spherical camera would give the same results as the physcam in terms of lighting...

Lele

[teabag]

Hello Lele,

ive tried the dome camera, but it does not have any exposure settings.
so the result i get is overexposed as if was rendering the scene from a perspective view if u know what i mean....

another thing is, when i set the dome cam, it does not give same result as spherical with 360FOV (the angular look)...so i suppose the dome cam is still in its early stages of developement...

i think the only way is to get rid of the sun and sky and do the clasical LWF render without any physical properties....

The only thing that surprises me is why the chaos guys got rid of the override FOV setting for the physcam.

[cpnichols]

Hello Lele,

ive tried the dome camera, but it does not have any exposure settings.
so the result i get is overexposed as if was rendering the scene from a perspective view if u know what i mean....

another thing is, when i set the dome cam, it does not give same result as spherical with 360FOV (the angular look)...so i suppose the dome cam is still in its early stages of developement...

i think the only way is to get rid of the sun and sky and do the clasical LWF render without any physical properties....

The only thing that surprises me is why the chaos guys got rid of the override FOV setting for the physcam.

You can still do an exposure control using the Color Mapping, and taking the Bright Multiplier to 0.001 or something like that.

[teabag]

this is what i am getting now with dome cam FOV set to 360

not sure how to work with this though as i was used to angular look of the spherical cam ....

this is the WIP scene..i want the dome cam to be set on top of the table in the middle


this is the probe i am gettin with dome cam fov set to 360mm. taken from just above the notepad..


thanks for the hints guys so far

martin

[Micha]

Sidenote: I don't use 3DSMax, so my only access to the current system is my SketchUp beta test license. And here I can disable the phys cam and enable the previous standard cam with spherical projection (multiplier of the color mapping at 0.05).
I think, this UI makes sense, because 360° panoramas dosn't need phys cam effects. So it seems to be a problem of the Max UI, if I understand right.

[teabag]

Sidenote: I don't use 3DSMax, so my only access to the current system is my SketchUp beta test license. And here I can disable the phys cam and enable the previous standard cam with spherical projection (multiplier of the color mapping at 0.05).
I think, this UI makes sense, because 360° panoramas dosn't need phys cam effects. So it seems to be a problem of the Max UI, if I understand right.

well i can do that too in max...use standard cam, direct light for sun, lwf....but i thought i could use the phys cam for this as well.

i dont agree that 360 panoramas do not need phys cam effects!!!! if u r making interior HDRI that is goiong to be used later on for natural lighting and reflections and even if not for this purpose....being able to render off an angular map from a scene shouldnt be a big problem imo....but somehow 4 me it is cos i cannot get the dome cam to render it and i think it is not capable of rendering an angular map at all.

[studioDIM]

ive tried the dome camera, but it does not have any exposure settings.
so the result i get is overexposed as if was rendering the scene from a perspective view if u know what i mean....

This is what i meant: there has to be a physcam exposure (for a given lights/materials setup) which leads exactly to the values of an unexposed camera.
So set up your scene without any gamma, and no physcam.
Pick the top-left pixel of your image with an unexposed camera and note down the first float value (R).
Render the same view with the Physcam, re-pick that pixel.
divide the newly picked pixel by the old picked one, and divide the ISOs of your camera by the resulting value.
ie: original pixel was 1.000 Red. (only the leftmost float value is considered)
Exposed pixel is 3.200 red (eg. at 200 ISOs, the physcam defaults)
3.200/1.000 = 3.2 (new pixel / old pixel)
200 / 3.2 = 62.5 (Camera ISOs / multiplier= camera ISOs)
or
30 * 3.2 = 96 (1/seconds exposure time / multiplier = 1/seconds exposure time)

Once matched with the standard cam, you can go about with tweaking your scene as view through the physcam, and benefit from DoF and whatnot should you need it. Then you'll switch tot he domecam to render the panorama (which matches perfectly the mapping types available in max)

Hope this helps.

Lele

[percydaman]

correct me if I'm wrong, but if the physical cam is built around the model of a real life camera, shouldn't you have to perform the same operation in order to create an hdri image? ie render several images at different fstops and then load them all together?

[teabag]

thanks Lele, will try that....just need a little time now to finish modelling the scene ....i wish i had your knowledge though ...lol

percydaman: you can sure do that percy but no chance u would get that to work as an HDRI reflection probe. normal physcam wont give u angular HDRI render

vlado: is there any chance that dome cam would have some of the properties as physcam has?

[teabag]

so if i get this as an output from dome cam....what mapping type in vrayHDRImap do i have to use? spherical?

what should be the correct value for the fov parameter if i wan to create an HDRI reflection map to light the stuff on the table....the dome cam is placed 5mm above the table surface looking up...

do u think 180mm should be enough for this purpose?

[jow]

You could try using a Physical cam set to the correct exp. All need to do is drop the focal length to about 10ish mm, then up the distortion value to about 0.5 ish. This will give you a physical fish-eye lens with about 170-180° view like a real fish-eye lens....
Then just place the cam on the table pointing straight up.
Seems to work ok..

[teabag]

ha..... there u go lol....cool

i think 170 fov should be plenty for this purpose

thanks everybody