hdri
I was hoping to get some help with this:
I have been using HDR environments in Iray...but i am not really getting satisfactory results because my final renders come out to dark and without shadows. I am using the free hdris from HDR LABS
http://www.hdrlabs.com/sibl/archive.html
What i do understand is that each hdr comes in a zip file which contains 4 different items:
a BG a ENV a REF and a SUN...and all these 4 are supposed to work together and make one single environment that lights the scene with reflections and shadows complete...only in Iray i can only load one of these in the environment map slot...usually i load the biggest size hdr...but as you can see in my render...this is not enaugh lighting for the scene...the reason being because the other files also have to be loaded together to form a complete lighting rig with shadows and everything...but its not possible to do this within Iray...in the environment slot you can only load one file at a time...and due to the fact that all the files must work together...the final rendered scene will remain underlit.
Correct me if i am wrong...maybe i am doing this the whole wrong way...thats why i need help...i also read somewhere that you have to add extra lights to the scene when using these hdris...but how is this done?...i have no idea...is there any tutorial on how to properly use hdris within Iray?...
Here is a scene i made with one of the free hdris from HDR LABS...clearly the scene is very poorly lit...sometimes i crank up the environment intensity...but this is not supposed to be the way to do it....even then i would get no proper shadows.
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Comments
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I don't see what the problem is with that HDRI...if you look closely, you'll see that she is in a somewhat shadowed area and not in any of the intense lit areas. My guess is that if you rotated the image, you would get more shadow and more light, overall.
The light appears to be shining straight down. She has shadow below her chin, the inside of her thigh and below her feet, very soft shadow but it is there.
I also don't see any problem with this light, just maybe your expectations. While sometimes a HDRI image give all lightning necessary to the scene, sometimes you need add some extra light to make it more interesting. As mentioned above, you can rotate the HDRI to get a better light angle, or may you can just add some photometric lights pointing directly to the subject. I use HDRIs with photometric lights all the time.
Think as a photographer. This picture could be an editorial or fashion photoshot, so you certainly would add some directional lights to detach the subject. How many lights and from what direction would depend from the mod intention which you would be looking.
The bright spot on the left side of the background is not reaching her...it's being blocked by the building...so she is standing IN shadow. The vending machine light isn't reaching her, either, so what light she is getting is coming from 'off camera'...close to straight down.
try rotating on the y axis (Dome Orientation Y) to get the light in the direction you want. You can also increase the brightness, or decrease it (Environment Intensity).
Also, deleting or invising walls or rooves that are not required for the shot can let in more of the HDRI.
You can use the jpeg version as the texture on a skydome sphere during setup. This will help you 'preview' the output without rendering. If you rotate the dome, rotate the Environment in the render settings the same amount. Before rendering, delete or hide the skydome.
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You can if you enable the Iray preview mode in the aux window...the problem with that, is it pretty much needs an Nvidia video card, or it slows everything down as if doing a full render, at least in my experiance. I have yet to try anything on my son's machine...he's got the 'good' card...I've got the 1 GB 440.
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I have been able to use the Iray preview in the Aux Viewport, with a pathetic little 450 GTsomething. Essentially the preview drops back to smooth shaded while working and then comes back after a stop doing stuff, so it isn't by any means fully interactive but it is - just -usable.
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