How to use hdri environment map?

[rws]

Hi,
What is the best way to use hdr environment maps at this stage?
Brute force and irradiance maps take monstrous amount of samples/quality to clear up, and using dome light appear strange:

I thought perhaps "intensity" or "shadow" under the texture influence might have some effect but they produce error on export.

Is there a method?

Thanks

EDIT,
If, for this to be possible there needs some more development to the settings of dome/hemi light - how much $$ will encourage it close to the top of your to-do list for early next year? (after what your mind is working on now)

[rws]

Hi bdancer,
I will donate 65 USD (~50 EUR) on your paypal donate button, if you get this hdri/domelight business all working quite soon.
Let me know

[bdancer]

Re: How to use hdri environment map?

Hm... will try to do it as soon as possible =)

[jorisAR]

Re: How to use hdri environment map?

I'll ad another 50 euros to that =)

[voytov]

Re: How to use hdri environment map?

BTW Andrey,
If I put a dome/hemi light into scene it causes quite visible noise in renders (also when hdri map is connected to that light). I can fight it increasing Image sampler Max subdivs value significantly... But should I ?
Before enabling the dome light the image was smooth and sharp.. (and rendered much faster).

[rws]

Re: How to use hdri environment map?

Hi bud,
Any news/thoughts?

Thanks

[arquitecto]

Re: How to use hdri environment map?

I have discovered that some hdr images dont have this issue.
It seems that this great amount of noise only appears on hdr with small and few bright areas ( sunset and night)
Bright hdr renders fine.
Maybe if we could increase subdivs for world texture this issue would be solved.
Can someone see if 3dmax has this setting?

[rws]

Re: How to use hdri environment map?

Low contrast hdri's dont have the issue by their nature. If you want sharp realistic daytime/sunset shadows you need high quality images with huge contrast between the sun and sky, this is where the unoptimized envmap slot completely falls apart at giving is a good image in a realistic time (if ever).

The reason for using hdri's on a dome light is because of the importance sampling(and other things) dome light has, it makes vray trace more rays in the direction where most of the light is incoming. Instead of evenly distributing samples from the entire environment map.
In the case of a sun hdri, it will focus on rendering light from the brightest spot(sun).

Unfortunately only low contrast maps render clean enough to be used in the envmap slots, but alas you cant get realistic sun/skylight from that.

[bdancer]

Re: How to use hdri environment map?

I've made a few additions - please test.

[rws]

Re: How to use hdri environment map?

Thanks, it appears mapping is correct now although there is some problem.

I'm running some comparisons with CGSkies test scene, this is where I notice the flipping in comparison (who's correct?)
This is the image I'm comparing with:
[attachment=1:2p2agitm]CGSkies_0228_renderspheres.jpg[/attachment:2p2agitm]

Though there appears to be some sort of problem with the light it emits. I don't know whether this is to do with my settings or not.
This is my result, (Hemi intensity 30, Texture multiplier 30, Texture Gamma corrected 0.6). I'm using the sample .hdr from cgskies 228, It's probably not possible to get the sharpest shadows from that resolution but there should be something.
[attachment=2:2p2agitm]1.jpg[/attachment:2p2agitm]
The sun is having minimal effect, odd glow from under the cubes and the ring around the reflection on the main sphere (I'm 95% sure its not aliasing)


I've been fidling with the settings to see if there's any result that could help you or me. I set some crazy settings (hemi intensity 1, Texture multiplier 100, Texture gamma corrected 0.2) and the sun is having effect now, wrong as it may be.
[attachment=0:2p2agitm]2.jpg[/attachment:2p2agitm]


Here I have a zoom of the reflection ring.



Now I scale the ground circle down and zoom in more. Notice the black ring of the empty sky increasing.
The light ring appears to be an area of the ground circle which is being effected by the light more.



Now I return the circle to the original size and place a pink plane (much smaller than the circle) over the ground circle, and a green cube on the corner of that pink plane.
Check out the shading on that cube too.


Interestingly it looks like everything but what is out in that reflection ring is... possibly some sort of shadow.

Now I should have done this before, but now I move the camera.
Now check it: Crazy.



Here is the scene:
http://dl.dropbox.com/u/24789652/cgSkiesTest.blend

Hope this helps.

[arquitecto]

Re: How to use hdri environment map?

Hm interesting.
I was using world and added a texture to it. Thats the reason for my comment.
I used the background multiplier and the gi slot to balance the light.
The hdr you used gave me no noise on the older build.
But with hemi light it in fact gave me lots of noise on the older build.
Interesting because the gi generated by the world texture has no subdivs and works perfectly well with good and big hdr textures.

But I must agree that hemi lights are much more flexible. Have it working is important.

[rws]

Re: How to use hdri environment map?

@bdancer, Here is another tidbit of information. I select intensity checkbox and the odd line is affected:
[attachment=1:1s1fiwea]int.jpg[/attachment:1s1fiwea]


@arquitecto
Try this one 340, for a better example of problem with not importance sampling. In this one the point of the sun is smaller as well as brighter.
[attachment=0:1s1fiwea]splotch.jpg[/attachment:1s1fiwea]

[arquitecto]

Re: How to use hdri environment map?

I will try it.
Dont know if its hepfull for bdancer but one thing I have noticed is that blender treats world textures diferently from other 3d software.
If you place a texture on the world properties blender internal squeezes it to the top half sphere of the world.
It seems like this is a mapping problem that is causing al this noise...
But I will try to see what I can figure out from here...

[arquitecto]

Re: How to use hdri environment map?

Hi,
With hdr texture on world settings with backgraound and gi override i can get rid of the noise and just need to increase irradiance map settings.
With hdr on hemi light I still get the same noise you have.

[rws]

Re: How to use hdri environment map?

@arquitecto,
Could you show your result of the scene with one of those cgskies, using hemi lamp? I wonder if it has the same problem as mine.

@bdancer
It appears though as if there is something funky with these skymaps that vray doesn't like or something strange in my vray version (even though one of the cgskies samples is rendered with VRay 1.6.2).

I did some more mucking around, first thing I did was to remove the cgtextures logo from the bottom of the image using compositor to reduce confusion, this removed a messed up reflection on the bottom of the main sphere (which has no sense to be there anyway):
See in this pic:


Next thing was to try others maps, HdriLab's and Dutchskie's. These are actually full environment maps, not half black:
Seems ok:



Now was some more button fidling, I change the filter type on the image to area.
Low and behold the sun actually appears to come out, however only during light cache generation stage (of course afterwards it turns into a mess with such a setting)
Check this:

The other files are not effected by this setting.


As it seems probably not something under your control Bdancer, I believe I will send your money through soon.

I will try some further things also.