[brodie_geers]

I'm having a difficult time with my HDRI's. They seem to be washed out, which is typically a gamma issue, I know. But I'm not sure how to fix it or where the problem is.

Here are some images from some recent tests.

Dosch backplate. This is what the IBL background and environment SHOULD look like.


Rendering with a dosch HDRI. This is one of the lower res images presumably recommended for the illumination channel


Rendering with a different dosch HDRI. Same as previous HDRI but it's a much higher res image that comes in the package. Presumably for reflections and background channels.


First of all, I'm not sure why Dosch seems to have these HDRI's of diff resolutions burned in with different gamma info (this is apparent from opening them up in Photoshop). I'll take that up with Dosch unless anyone has any idea why that would be. Secondly it's apparent that both of them are very washed out compared to the backplate which means that I have to replace the background (fine), but it also means that my reflections and lighting are washed out as well, yes?

I've tried some other HDRI's in case it's just an issue with the Dosch pack I bought, however I have no reference to tell me what it SHOULD look like so at that point I'm just guessing that it's washed out in the rendering. Is there some more scientific method of testing I can do here? And has anyone else had this issue? I presume that the gamma for the HDRI's being inserted SHOULD be 1.0, yes?

-Brodie

[brodie_geers]

btw, never mind the huge splotches on the rendered images. Dosch didn't do such a hot job of splicing them together apparently.

-Brodie

[Mihai]

Yes, it's strange they create them like this. You can adjust the gamma in PS, adjust>exposure. Move the gamma slider to the left until it says 2.2 so basically removing that gamma info. The HDR should have the correct contrast now.

[brodie_geers]

Thanks. I emailed Dosch about the issue. Unfortunately, neither of them seem to be correct. There seems to be a difference of 2.2 or .45 depending on which way you're going. Yet neither of them matches up with the backplate, which logically must be 2.2 and visually looks correct.

-Brodie

[Daniel Hruby]

I am looking for some HDR answers too. I have some huge 70MB HDR Sunsets from Hyperfocal. The EULA has some info about what files to use.....

Included with each Hyperfocal HDRI Sky is:

- One full size HDRI in exr and hdr format for use as a background and reflections.
The full size HDRI sky can be used for lighting, backgrounds and reflections depending on the software you are using and
your requirements. For some applications you will want to use the low resolution HDRI for lighting. Rendering your scenes
with a HDRI sky background allows you to use a dynamic exposure level or "shutter speed", especially useful in animation simulating video footage. When rendering to a HDRI output format such as .hdr or .exr, it also allows you greater control
over the final look and feel via post processing.

- One full size LDR jpg for use as a non dynamic background.
If your scene features no reflections and you do not need any of the benefits stated above, you can replace the HDR you are
using for your sky background with the LDR. If you wish to use a different exposure level, you will have to load the HDRI sky in
a HDRI image editor such as HDRShop or Photoshop CS2 and adjust the exposure settings before saving out in your 8 or 16 bit format of choice.

- One small HDRI in .exr and .hdr format for use in lighting.
This lighting HDRI comes unblurred, allowing you to blur it to a level of your choosing either in a 2D HDRI editor or within your
3D application.


How does this apply in Maxwell? As suggested above, you could use the LDR.jpg for background/sky. BUT Maxwell won't load a JPG File type into the IBL Slots. So, is it Hi_res HDR For all slots but Low Res HDR for Illumination?

Secondly, the Intensity values are a bit of a crux for me too. The default of 1 seems pretty low. IS that 100%? is a value of 100 = 100%? It seems like if I set the illumination intensity to 20, the lighting starts to looks like something is happening, but it seems washed out. Is there a relationship with the background image tot he illumination intensity as well?

[Bubbaloo]

As suggested above, you could use the LDR.jpg for background/sky. BUT Maxwell won't load a JPG File type into the IBL Slots.

You can load the background jpg image into Maxwell and save it as HDR, then use it for the background slot. Then use the real hdr/exr for the reflection, refraction and illumination slots. Also, the higher resolution hdr's are best as they will provide better lighting and reflections/refractions. The blurred low res hdr's are for other render engines.

[Mihai]

Unfortunately, neither of them seem to be correct. There seems to be a difference of 2.2 or .45 depending on which way you're going. Yet neither of them matches up with the backplate, which logically must be 2.2 and visually looks correct.
-Brodie

How much does it match when you move the slider to the left ('resetting' the gamma)? Probably it won't match completely with the regular LDR background photo because first it went through some tonemapping from camera to software giving it that look, second perhaps Dosch further enhanced it (saturated the sky, increased contrast etc). Plus the HDR you are viewing on your monitor is Photoshops tonemapping to be able to display that HDR on your monitor. It may look different opening it in another HDR application. But at least if you can remove any initial gamma stored in the HDR, you avoid too washed out lighting from it when rendering. Then matching the render with the image is a further step to tonemap the render, which initially is tonemapped linearly so you could use a plugin that mimics different filmtypes to get it closer matched to the background image.

[Daniel Hruby]

Is there a way to have the physical sun contribute to the shadows with HDR? Even with a bright sun, sharp shadows seem elusive for me.

[Mihai]

You could use the Save to HDR in Studio Physical sky settings, then blend that HDR with your photographic one in PS. It will give you the very bright sun needed for sharp shadows. Or easier, in PS lower the exposure of your HDR until you see the sun actually starts fading out instead of it getting smaller but still being very bright in the middle. Then brighten just that small area using the Burn tool or similar. Resave it and it should give you sharper, darker shadows.

[pipcleo]

Any chance of reintroducing the physical sky/HDR lighting combination from 1.7 ?
What was the reason for removing this option from v2 anyway ?

[Daniel Hruby]

+1, this is why I was asking. I thought I recall that feature being there and now its gone. I think that that 1) Physical Sun checkbox should be added back, 2) interpolation really should only be on the illumination channel only, and the ability to load LDR. jpg into the background slot would be nice.

[pipcleo]

add your sig for this to the wishlist !

[brodie_geers]

Just wanted to post an update on this issue, at least as it relates to Dosch. As it turns out my original email got eaten by gmail somehow (it's not in my sent folder anywhere and was never received). I sent Dosch a new email pointing out the issues and got an email from Sebastian Dosch the following day who agreed that the quality of the HDRI's in that pack weren't up to snuff and that he'd be taking them down from the site (which I notice he's already done at this point) and he offered a couple solutions to make it up. I'd also had an issue a long time ago with some 3d tree models I'd purchased and Sebastian took care of me in a similar fashion. Just thought I'd put that plug in for Dosch's customer service which is phenomenal.

-Brodie