HDRI: No shadows without a Corona sun present

[AnubisMe]

This has really been bugging me for a while but I just can't get any good shadows in my scene with just a HDRI. I have tried several HDRi maps and its as though shadows practically don't exist. I load my maps with 32 def exposure and set the gamma to around 0.75, and still the shadows are weak as hell. I even tried custom editing my maps so the sun is just a pure white circle with a very dark blue sky. I think maybe my problem is the highlight exposure? Both metal Ray and Vray require a skylight in the scene does Corona also require that? I will post en example tomorrow of what my scene is looking like right now.  One of the maps I am use is peter guthrie blue sky sun maps so I am not using weak maps by any means.

[Ludvik Koutny]

Not really, you just need a good map. Most of the HDRIs sold are claimed to be HDR and yet they are just edited 8 bit images. Also, a lot of HDRI vendors are dumb enough to save EXR with wrong gamma, such as Dosch, so you have to pass it through colorcorrect node with 0.455 gamma. Lastly, when opening HDRs, you need to make sure you open them with 32bit depth and def. exposure.

[Ludvik Koutny]

I got this one at work http://www.3six0.net/HDRILibrary/image.php?image=7414 and it creates nice crisp shadows without any problems.

[Ondra]

This has really been bugging me for a while but I just can't get any good shadows in my scene with just a HDRI. I have tried several HDRi maps and its as though shadows practically don't exist. I load my maps with 32 def exposure and set the gamma to around 0.75, and still the shadows are weak as hell. I even tried custom editing my maps so the sun is just a pure white circle with a very dark blue sky. I think maybe my problem is the highlight exposure? Both metal Ray and Vray require a skylight in the scene does Corona also require that? I will post en example tomorrow of what my scene is looking like right now.  One of the maps I am use is peter guthrie blue sky sun maps so I am not using weak maps by any means.

send me any map with this problem, I'll take a look

[Polymax]

I got this one at work http://www.3six0.net/HDRILibrary/image.php?image=7414 and it creates nice crisp shadows without any problems.

I agree, no problems with shadows from HDRI, if use good HDRI textrure.

[AnubisMe]

Not quite the result I was looking for. I will get back to you Keymaster for getting you some files to look at.

[Sam75]

I am able to get nice shadows but then we have a problem with fireflies, workaround with corona sun is to hide it from reflection but what can we do for hdri ?

Can't we have an option to clamp the hdri for reflection only ?

[Ondra]

Do the objects with fireflies have reflection? If yes, then you either need to blur this reflection, or use reflection environment override (with something without the bright spot)

[Sam75]

Yes they have reflection

[Ludvik Koutny]

If the trees have strong highlights under HDRI sunlight then they would have exactly the same highlights in real world. It is not a bug, the problem is that people tend to make materials a LOT more reflective than they are in real world, so there's your problem ;)

Matching real world reflection and glossiness of an average leaf material will do the trick for you. If you for any reason need leaves to look like glass, such as in your case, then you can alternative duplicate your bitmap, open the HDR/EXR map with only 16 or 8 bit depth...  and then put the bitmap opened at lower bit depth into reflection environment override slot.

[Sam75]

If the trees have strong highlights under HDRI sunlight then they would have exactly the same highlights in real world. It is not a bug, the problem is that people tend to make materials a LOT more reflective than they are in real world, so there's your problem ;)

Matching real world reflection and glossiness of an average leaf material will do the trick for you. If you for any reason need leaves to look like glass, such as in your case, then you can alternative duplicate your bitmap, open the HDR/EXR map with only 16 or 8 bit depth...  and then put the bitmap opened at lower bit depth into reflection environment override slot.

The difference with reality is the pixel scale. I will try to render it at a much bigger res to verify that.

[Ludvik Koutny]

If the trees have strong highlights under HDRI sunlight then they would have exactly the same highlights in real world. It is not a bug, the problem is that people tend to make materials a LOT more reflective than they are in real world, so there's your problem ;)

Matching real world reflection and glossiness of an average leaf material will do the trick for you. If you for any reason need leaves to look like glass, such as in your case, then you can alternative duplicate your bitmap, open the HDR/EXR map with only 16 or 8 bit depth...  and then put the bitmap opened at lower bit depth into reflection environment override slot.

The difference with reality is the pixel scale. I will try to render it at a much bigger res to verify that.

That is not completely correct. The difference ends as soon as you capture that image with a digital camera, which projects it's luminance measurements on pixels. The reason you do not see any of these strong fireflies on photo is that they are usually covered by some secondary effects, mostly glares. And if you take a picture of a tree under sunlight, it is not usually full of glares. And that is because leaves are not nearly as reflective as you have them.