[Half Life]

I tested them out quickly and at default exposure values they would need to have an IBL "Intensity" value somewhere in the 50-60 range to be useful.

Best,
Jason.

[adzling]

thanks jason, so you think my HDR images may be part of the problem then..

looking at commercially available HDR images such as those from HDRI-studio.com i can see what you mean....they have far more black space than my freebies do....

if i pump the illumination intensity up around 50 as you note the image gets very washed out

[Half Life]

Yes, that would be my experience -- especially with reflective surfaces.

Best,
Jason.

[adzling]

thanks it's good to know my assumptions are getting more correct

so does anyone know what the ideal resolution for an HDRI within maxwell is?
or is that like asking "how long is a piece of string"?

i'm asking cause i also have some insanely huge HDRIs my friend dropped on me, however their resolution is a mind-numbing 10240 by 5120...
which i would imagine ain't gonna help the render time...

[Half Life]

Well, you have to remember that intensity will also depend on exposure -- I specified the default exposure, meaning I created a camera in Studio and touched none of the settings... typically that exposure would be used for outdoors "sunlit" shots so the intensity would need to be higher to compensate, but it would also help the contrast a bit.

Bear in mind if you are lighting a shiny white or mirror type object then you will want lots of contrast in the IBL to add interest into what would be a pretty "flat" looking object to begin with.

The high resolution will not hurt the render time, although it may be a problem if your system is not 64-bit (and have lots of Ram) -- but otherwise higher resolution is better.

Best,
Jason.

[adzling]

yes understood about the exposure settings..mine are at default.

i am going to try and fudge with the contrast on the HDRIs i have before i spring for a retail package from someone.

do you have a studio lighting type HDRI package you like that doesn't cost an arm and a leg?

-----edit-----

well i opened the HDRIs i have in photoshop and using the offset slider under the exposure menu option i was able to make it a lot punchier/contrasty and this seemed to dramatically improve the render result (it's a glossy white object with flat and some curved surfaces).

thanks again this thread has been incredibly helpful to me.

[Half Life]

do you have a studio lighting type HDRI package you like that doesn't cost an arm and a leg?

No -- I would say photoshop in some cases but that costs an arm and a leg as well... The reality is for studio-type lighting most professional options will cost a decent amount.

If this was not a common problem for your renders, meaning you tend to light using physical sky or with emitter planes then I would say just mod the freebies in photoshop and work around the limitations.

However if you find that this a common issue for you then I would recommend HDR Light Studio (which has direct support in Studio) and while it is not cheap it is in a comparable price range to purchasing a few nice sets of studio type lighting from suppliers like these:

http://www.hdri-studio.com/index.html

http://www.doschdesign.com/products/hdr ... ts_V2.html

With the advantage of being completely and dynamically flexible to the needs of your project.

Best,
Jason.

[Half Life]

You may find you get better results from the "exposure" dialog in Photoshop for the studio005 file with settings of:

Exposure -0.25
Offset +0.05
Gamma 3.5

and end with a Gaussian Blur with the radius of 0.5 pixels.

Also worth saying is you can do some of this in the Maxwell render app as well.

Best,
Jason.

[adzling]

hmm when i do apply these settings I am getting a very blown-out look, verrrry white.
was this your intent?

in my last experiment with a different HDRI i just dropped the offset to something like -0.25 with no gamma or exposure correction.
this resulted in a very contrasty image with pronounced dark and light areas.

[Half Life]

That is odd... with those setting I get very smooth shadows and highlights and good falloff between them -- I'm still using an intesity of 50 in Maxwell as well so obviously there is some disparity between our camera settings or perhaps the settings would yeild different results with the full-rez files.

Either way my only concern was that excessive use of offset can lead to harsh "posterized" type edges in what is essentially meant to be a "soft box"... but as they say "if it isn't broke don't fix it"

Best,
Jason.

[adzling]

ah, i was referring to the look of the actual HDRI in photoshop.
i haven't tested the HDRI modified with your recommendations within maxwell yet.

my prior test with the HDRI mod'd with an offset of -0.25 used an IBL setting of intensity 10 within Maxwell.

[Half Life]

It could be possible that the settings have changed the way they work in newer version of Photoshop -- here's what I'm getting with those settings:



Best,
Jason.

[adzling]

yeah something screwy is going on.
I am using photoshop CS3, not sure what version you are on but somehow i doubt it's a photoshop thing.
could have to do with the delta between mac and PC gamma (assuming your are using a PC, they have a gamma setting a lot darker than macs).

here's what i get when i use the studio 05 file with your exposure settings noted above:


by way of comparison here is a stock hdri image

and the same image with just a modification to the offset (can't remember exact setting but it was something like -.15 or so)


that final image above is what i am currently using in my test renders for a product type shot with a glossy white object

[Half Life]

Yeah, your mods look better but you do push some values to a flatline black which can lead to undesirable results -- the easiest way to fix that is to copy and paste the original HDR over the top and fade back to 25-35% to work a little of the shadow details back in.

Definitely could be a Mac/PC thing on the gamma as it looks like yours went the opposite direction as mine.

Best,
Jason.

[adzling]

thanks for the tip, i did think those blacks looked a little nutty