Re: Hdri Free
Olegario Benford
Based on my understanding, if the quality of the HDRI is high then the sun on it will be strong enough to produce good, accurate shadows. If not, well then you can help yourself by adding a V-Ray sun to kind of enhance the effect of a sun being present. Quality HDRIs usually have more information in them ala the sun power is still there once you go to really low exposure values (this is just an example).
They are of a high quality most definitely and shadows etc are on point. You mention exposure at lower levels, I assume its correct to increase the camera exposure to compensate for lower light levels in the scene? i.e. obviously not having a Vray sun present in addition to a HDRI means there is less light being generated. I'm usually set with an F-stop of 10-14 with both a sun and HDRI, but using a HDRI alone I'm at F-stops of 2 minimum. Is this normal/expected? Would one look to increase the render multiplier within the Vray HDRI material too?
As said in the previous post, if the HDRI is of sufficient quality it should be able to light the scene and cast good shadows with ease. If you are still struggling with the sharpness of your shadows, try playing with the gamma of the HDRI.
The reason people inventing/ using sun or other directional light together with HDRI Dom lighting is to overcome the unsharp shadow problem that usually arise whenever use hdri map. In order to get a sharp shadow in case gamma inverting option is not helps much. Because many of hdri light source usually diffused therefore the shadow is not too obvious whenever one need that fx in their scene.
I primarily use HDRIs to light the scene and for the background image. I copy the HDRI to the background so that I can adjust the settings independent of the lighting. Then between the camera exposure and the HDRI used in the GI I get nice results.
People before me already answered this one but my two extra cents to this debate would be that yeah, try sticking to the values that are deemed "believable". It is normal to tweak them up and down, left and right but just for the sake of keeping things somewhat averaged I tend to stick to the more realistic values - I suppose this might help in translating materials you develop from one scene to the next.
There's no need in extra VraySun. Just open exr file in Photoshop, steal the color value in the center of the sun but pump up the value to +6-11 stops; then make one touch of round brush with say 90% softness in the center of the sun (to find it, you should lower the exposure`display slider).
Hi, Im trying to take some steps into vray and the one thing i just plain cant figure out is hdri's they are far too bright in the viewport and the dome light doesnt light my scene when the texture is applied everything is still pitch black. Why is it so much more complicated to set up HDRI lighting in Vray than in Mental Ray?
I can do that fine. I'm actually using one of peters skies. But it is just completely white when I set it as the viewport background as if the brightness has been bumped up far too much and the lighting in the viewport doesn't work at all in realistic mode the model is still completely black so I can't see it in realtime. It works in the render but I have nothing to judge the brightness in the bviewport its all guesswork until I render.
That's because Peter Guthrie sets the "default" exposure of his HDRi internally to be so high, not sure why, it's definitely outside of industry standard. I think it's because it let's him use them with 1 multiplier (at Dome, and at texture) with correct camera physical settings that were used when he took the mid exposure of these HDRis.
I think he also describes the workaround, which is quite simple, instead of 1/1 (regular/rendertime) multiplier in VrayHDRi material, he sets the regular multiplier to 0.01 for example, and render time multiplier to 100.
Riiight that makes sense now. So thats solved the exposure issue. The viewport shading problem is still happening though. Am i using the dome light correctly? Is it used in the same way as a MR skylight or does it need to be above the groundplane?
It's all the same. Multipliers (unless you set 1/1 in texture/light and use photographic values which don't make much sense with IBL lighting unless your HDRi is calibrated as well) are simple potato values. It doesn't matter what the value is.
I just wanted to ask because I could never really work with HDRIs inside Rhino with V-Ray. For some reason I never end up getting the result I am looking for, but most importantly, it is always a pain to work with them.
Why?
Mainly because they take too long to load and display changes. I have a pretty powerful pc and still it is not like I see with other 3d software where you can rotate hdris live, and get a preview instantly. Blender, Cinema, w/e.
a- a high resolution HDRI means more light rays shot to the scene that may cause noise into the image.
b- Previously I was storing multiple formats of the same image. the first one is a low resolution HDR with blur applied to it for a softer lighting & shadows, the second one is a higher resolution HDR for Reflection / Refraction. and a super high res LDR (.jpeg or PNG) for background.
So, my suggestion is to have 2 separate textures, Low Res HDRI (hdr or exr) attached to the dome light, and a Higher resolution LDR (jpeg) attached to the background slot in the environment tab.
Keep the Tex. Resolution to 512, and add a seperate background map.
yes, it is very common in the old days, now vRaySky is more improved. so, it is slightly becoming obsolete. especially you need to do additional tweaking to make sure the sun aligns to the light source in your HDRI.
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