Blochi's HDRI challenge

[Cyborgguineapig]

Wow very nice:applause:

[AdamT]

Wow, great job Chris! :thumbsup: :thumbsup:

[Chrissyboy]

Nice job! I feel a bit reluctant to comment as it's so far ahead of anything I've managed, but... the one thing that stood out for me as obvious CG is the glass, the ultra-heavy refraction and zero shadow.

Are you allowed to comp caustics on afterwards, or is that against the rules?

Interesting site too, thanks for the link - that XSI render is good though, huh?

Good luck - C

[That Adrian Guy]

Wow.

No crits here... The bed and the couch are top notch!

Maybe you can do some P.P. to get rid of the foggy look?

[VestanPance]

That is amazing! But I am a bit confused...you didn't model everything in that picture did you. I followed the link and say that some of those objects are highlighted in red....are those the CG ones?

EDIT: OK....follow this link: http://hdri.cgtechniques.com/~blochi/show.php?id=326&PHPSESSID=0de729c8f91df882613c6d3029148c40

and it shows you what is real and what is not.....great HDRI image! I think I may give it a shot.

[Halogen]

looks very fun, i might give this a shot for my own experience :D

[LucentDreams]

looks very impressive, but I'd take out or continue tweaking the cup an saucer, the differences betweeen yours and the rel one are too substantial, your highlights are crisper and slightly brighter, the models are slightly different sizes and such, and the saucer especialy has a different smoothness to the surface.

otherwise fantastic job.

[Katachi]

Wire of the elements that are CG please. :)

[Chrissyboy]

Originally posted by Designer
Wire of the elements that are CG please. :)

Hi Samir - the whole scene can be downloaded from the competition site:

http://hdri.cgtechniques.com/~blochi/

It does take some figuring out which bits are real though!

Seeyou C

[chris_b]

Hey Guys,

Thanks for the encouragement.
The scene is provided in several formats and contains the camera, textures and an assortment of objects positioned on the table. The CG elements are
the large chrome ball (surprise surprise), the three glasses, the cup and saucer on the left, the plate, the knife/spoon/fork, and the two smaller balls near the french press.

Primarily, this is a lighting, materials, and camera matching exercise... and boy is it tough to get a close match!! I saw somebody elses post on the site (done in Cinema) and he had basically given up, blaming Cinema's handling of HDRI, so I felt compelled to jump in and try it myself.

Matching the blue ceramic material is really tricky... you can get really close, but that last 3% is very tricky. The glass is also a real challenge. I briefly tried incorporating caustics, but unlike Mental Rays photon tracing, Cinema's won't cast caustics based on an HDRI... it is worth trying to set up a caustics pass for a comp though. Also, it is really hard to get any substantial shadows from the glass (using the HDRI).

If you have a few minutes to kill, I would highly recommend that everyone try out the scene. We have a good opportunity here to push Cinema's new HDRI to the limit and maybe find its weak points in direct comparisson with the other major engines out there.

Here is a page showing wires of the objects:

http://www.blochi.com/gfx/hdri/

PS. It is rendered in one pass with no alphas (i think that is one of the rules) so that you can't do any colour correction and tweaking in post.

[AdamT]

I wonder if it would be considered cheating to use lights for caustics (no diffuse) and/or to enhance shadows?

I would suggest using Oren-Nayer for the pottery materials rather than Phong. Heck, I may have to give it a try myself!

[stefkeb]

Can you use a smoother anti-aliasing in the renderFX from Cinema4D itself? Could help smoothen the look and fade in more with the environment.

Anyway, I tried it yesterday with the 8.0 demo and it didn't look any good, so it's all in the hands of the artist.

You mind writing down a few settings for others to learn about it?
(That's one of the reasons CGTechniques organises such a comparison-competition).

How do you make the table disappear and still receive shadows? I wasn't able to get it right... I can use the compositing tag on the table geometry, but it doesn't receive any shadows (maybe because the HDRI settings for the sky don't provide them?). Do you use the HDRI-image on a SKY-object or on a large sphere?

I'm also trying with Max, but so far it doesn't look that good... I guess it's down to trial and error again.

[chris_b]

For anyone interested, I have updated the scene with a few tweaks and have posted the scene file for download.

http://www3.sympatico.ca/kdagg/Apartment.c4d.zip

Perhaps somebody can pick up the ball and run with it :)

http://www3.sympatico.ca/kdagg/chrisb_blochi_hdr1.jpg

http://www3.sympatico.ca/kdagg/cb_blochi_wire.jpg

[g0tenks0]

haha most of it caught me as real i was just looking at the spheres

[AdamT]

Just noticed that the shadow direction is wrong. The real shadows are at about 5 o'clock, while the CG shadows are at about 7 o'clock. May need to rotate the HDRI.

[smoke]

The wine glasses kind of look like they are hovering
and the shapes are crisper then the original image, is adding a little blur against the rules? maybe use DOF....

[derwolpertinger]

apart from the shadows it looks pretty cool! :D but it is not only something wrong about the shadows direction, the shadow should also be a tad bit harder, just compare the shadows oof the cg cup and the real one, they are very different from each other. additionally the real cup is more enlightened inside than the cg one.

[chris_b]

hmm... interesting.
A lot of what look like shadows in the plate are actually a mixture of very diffused reflections in the wood and shadow from the window. I couldn't find
and easy one-pass method to incorporate the reflections, so I left it alone.

Have you had a chance to look at the file?

The HDR is definitely in the right position.
If you look at the reflections in the chrome, there is confirmation of that the rotation is correct. I set the sample rate pretty high also, so I don't think the inaccuracy of the shadow has anything to do with an undersampling of the .hdr.

HDRI seems to be able to generate pretty good shadows, but a dead match may be beyond its capabilities. The Reflections are fantastic though, and can enhance glass materials incredibly.

Another interesting thing, is that Cinema's photon tracer doesn't seem to cast cautics from the HDR (MR can).

[derwolpertinger]

yeah that's right caustics can only be achieved with normal lights. :( afaik the calculation would take way too long when the hdri had to create them.

[Shademaster]

Why not put the hdri sphere into a dicloner sphere + a light? Then remove the colored lights and give all the white bright lights a small amount of caustics?
That could work if you REALLY like caustics.
:)

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