Environment Sphere Map Reflection Cutoff

[mncarlton]

Does anyone know why the reflections on the building would stop like below? I have a spherical environment image mapped to the Environment/Background Switcher. It seems like the environment sphere is not covering the entire height, so then the building reflects blackness above. My environment settings are also shown below. This is using Mental Ray rendered, btw.

I appreciate any insight, thank you!

[Alfred.DeFlaminis]

Hello @mncarlton and welcome to the community,

I'd like to help with this rendering problem.  Is it possible there is a light in the sky there that could be blocking the environment rays?   Or some kind of photon emit radius issue with a directional light or something along those lines? 

To properly diagnose this I would need to get a look at the scene if possible.  I can create a private folder for you if you'd like, it makes problems like this much easier to solve.  If that is impossible, can you do a render with a chrome sphere instead of the building and post a screenshot of that?   Or, maybe remove the building and post the rest of the scene?  

This is a weird shape for it to be reflecting the blackness of the background, I would expect a straight line for that but in this case it's angular like a partially directional light or something along those lines.  Which version of 3ds Max is this for?  Thanks for the information!

Best Regards,

[Alfred.DeFlaminis]

Hello @mncarlton,

I just wanted to follow up here, any thoughts on my previous post?

Best Regards,

[mncarlton]

Alfred, thanks for the reply. That would be great if you could set up a private folder and take a look at the scene to see what's happening. Let me know how i can get the file to you.

Thanks!

[Alfred.DeFlaminis]

Hello @mncarlton,

No problem at all.  I have set up a private folder for you if you'd like to upload your files there. You should get an email about it shortly, and if you don't see it please check your SPAM folder. These files are private and will not be shared with anyone but yourself and the support staff. Please let me know if you have any questions. Please use at least an 8 character password or the Box account may not work properly.  Thanks!

Best Regards,

[mncarlton]

Ok, I uploaded the files to Box. I did find out that once I deleted the sky portals that I had set up in the corner towers, the issue went away. Now I just want to know why they caused the issue. Let me know what you find out.

[Alfred.DeFlaminis · Accepted solution]

Ah ok, that's a key bit of information @mncarlton.   In most high end renderers, lights act as a ray blocker.  (As a light source in real life isn't invisible.)  So the problem was that those lights were blocking the environmental rays.  You shouldn't need any portal lights for an exterior render, so just take them out and you should be good to go.  The point of portal lights is to direct rays into a small opening, so you use them for windows in an interior shot to focus the rays into that area, but for an exterior show they don't add anything to the mix.  

I didn't look at the file yet, but this is what was happening based on your previous post.   If your goal is to get more light onto the building, maybe there are actual light sources for that on the building itself, or you can just raise those lights up a bit higher so that the angle for reflections doesn't see them.  Would that work?

Best Regards,

[Alfred.DeFlaminis]

Hello @mncarlton,

I just wanted to follow up here, is it all working now?

Best Regards,

[mncarlton · Accepted solution]

Alfred, yes it works properly once I deleted the skylight portals. I had them entirely within the walls of the towers, acting as uplights. So I wouldn't have thought that they would have any effect on environment lighting outside of their boundaries. Anyway, thanks for your help!

[Alfred.DeFlaminis]

Happy to help @mncarlton, thanks for the update.  I was equally puzzled by lights acting as ray blockers when I initially discovered it.  

Best Regards,

[Alfred.DeFlaminis]

Hello @mncarlton,

I know this is resolved for you now, but something just doesn't seem right about them being inside the walls but affecting outside.  Is it possible they were scaled using the scale tool as opposed to the dimensions for the lights in the modifier menu?  Scaling lights can sometimes lead to weirdness and it's always best to use the dimensions in the actual light settings.  Just wanted to double check.

Best Regards,

[mncarlton]

I don't believe that I scaled them, but rather just sized them with the dimension toolbar. But I'm glad you agree that the portals shouldn't have affected the scene the way I had it set up. Either way its good to know that they can cause such an issue! Thanks again, Alfred.

Matt Carlton
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