Interior render help needed

[deadoxygen]

Hi all,

It's the first time I am posting something here for help. Any advice is welcomed!



I have been trying to render an interior lobby space with vray. All light sources are from light emitting objects (each set to an intensity of 1000). From the rendering it looks already too bright, however, I am still getting the blotchy spots on the floor and the ceiling.



This is how it looks like in rhino with ghosted view. (this is in NURBS, when i render I made everything into meshes using one of the tools provided by Micha's tool bar. Thanks Micha!)





I have read previous posts about the same problem, and have changed my settings accordingly (bumping up the subdiv and sample number, setting adaptive DMC to 0.85, etc). However, not only is the rendering speed insanely slow now (2 hours for an image of 800x600) the blotchy spots still seem to be there.




1. Could someone please suggest a way where I can get rid of them and get faster rendering?


2. Another thing is... right now, the wooden wall material is without any reflection. If I add a reflection layer to it, the whole rendering process is even slower. Any tips on this?


3. last question, how do I get the light rays from light bulbs that we normally see. Such as in Micha's sample renderings






Many thanks for all of your help!

[iamcapitano]

Re: Interior render help needed

Hey buddy, those blotches could well be caused by the light sources, how many subdivisions do they each have?

Also some settings need adjusting, in your irradiance map you have samples set to 120. This is very wrong as the samples blurs the detail in the GI. and could also be the reason for the blotches. Also, having such a big number also slows down your render tremendously. You should never have it over 30 (in my opinion).


Also, in the irradiance map you have the min/max set to -3 and 0. These are very high quality settings and also make the render take much longer, for testing you much smaller numbers (-6, -3 for example).


Also in the light cache your number of phases is set to 4. This number should be equal to the amount of processors in your pc, so if you have a dual core pc, change it to 2.

Change these things and your render will take a few minutes instead of 2 hours.

[iamcapitano]

Re: Interior render help needed

The light rays in those images come from omni lights (or rectangular lights) and then enhanced in photoshop to give it that "glowing" effect.

[deadoxygen]

Re: Interior render help needed

Hey buddy, those blotches could well be caused by the light sources, how many subdivisions do they each have?

Also some settings need adjusting, in your irradiance map you have samples set to 120. This is very wrong as the samples blurs the detail in the GI. and could also be the reason for the blotches. Also, having such a big number also slows down your render tremendously. You should never have it over 30 (in my opinion).


Also, in the irradiance map you have the min/max set to -3 and 0. These are very high quality settings and also make the render take much longer, for testing you much smaller numbers (-6, -3 for example).


Also in the light cache your number of phases is set to 4. This number should be equal to the amount of processors in your pc, so if you have a dual core pc, change it to 2.

Change these things and your render will take a few minutes instead of 2 hours.

Hey thanks so much for your reply. The reason I set sample to 120 is because I saw it in some previous posts about similar problems. It seems like the general solution is either to bump up the subdiv or to bump up the sample number, in which I did both. That's why I'm confused why there are still blotches.

For the question about how many subdiv for the lightsource. I simply used an emissive layer for the lightbulbs not any other light sources, so there is no subdivs for this (if I understood your question correctly)

I will try what you suggested and see if the blotches go away. Again thanks for your help!

[deadoxygen]

Re: Interior render help needed

The light rays in those images come from omni lights (or rectangular lights) and then enhanced in photoshop to give it that "glowing" effect.

Do you mean instead of using light emitting materials I should have also an omni light inside my light bulb object?

[iamcapitano]

Re: Interior render help needed

Ah okay, well that's the reason then, emissive lights aren't very good at sampling so should only be used to visualise the glow in the material. I bet you have very high emmisive intensities, and this is the reason for your blotches. Emmisive layers aren't used for lighting, you have to use an omni light or rectangular light in there for actual light.

And have the omni light outside the bulb (unless the bulb is made out of glass or a transparent material).

There is a video tutorial that actually talks just about this subject! so for a more detailed explanation (and visual aides) watch the whole video. Should be helpful to you!

http://www.youtube.com/watch?v=AnbPufCLEtY

[deadoxygen]

Re: Interior render help needed

Ah okay, well that's the reason then, emissive lights aren't very good at sampling so should only be used to visualise the glow in the material. I bet you have very high emmisive intensities, and this is the reason for your blotches. Emmisive layers aren't used for lighting, you have to use an omni light or rectangular light in there for actual light.

And have the omni light outside the bulb (unless the bulb is made out of glass or a transparent material).

There is a video tutorial that actually talks just about this subject! so for a more detailed explanation (and visual aides) watch the whole video. Should be helpful to you!

http://www.youtube.com/watch?v=AnbPufCLEtY

Great! thanks for the feedback. I will try what you suggested and post resulting images. Let's hope it will work!

[deadoxygen]

Re: Interior render help needed

Ah okay, well that's the reason then, emissive lights aren't very good at sampling so should only be used to visualise the glow in the material. I bet you have very high emmisive intensities, and this is the reason for your blotches. Emmisive layers aren't used for lighting, you have to use an omni light or rectangular light in there for actual light.

And have the omni light outside the bulb (unless the bulb is made out of glass or a transparent material).

There is a video tutorial that actually talks just about this subject! so for a more detailed explanation (and visual aides) watch the whole video. Should be helpful to you!

http://www.youtube.com/watch?v=AnbPufCLEtY

this is the new rendering with the omni lights placed at the bottom of each light emitting object

and here are the settings:




As you could see from the rendering there is still some blotches on the wall.

I followed the video tutorial recommended to change the settings of the omni lights, however they are still not giving me any light rays.


Any suggestions people?

Thank you!!

[deadoxygen]

Re: Interior render help needed

could anyone comment on if the omni lights are indeed placed at the right place? they create some weird shadows on the ceiling for some reason....

[Micha_cg]

Re: Interior render help needed

Point/spot/dir lights slow done rendering, so be careful for mass light scenes. Area lights can be set to "use with IM", that help for more speed too. In your case you could think about emitter materials + a long invisible area light for the whole floor. Add the right floor ground material and the scene could be better looking.

Also for interiors play with the IM subdiv count against splotches. I use 100 ... 200 or more subdivs some times. The IM calculation is quite powerful and fast, you can push it high.

Maybe the starterkit at the forum tutorial section could help you with some hints for the general usage. For example I seldom use IM max rate 0, it slow down the calculation to much and don't bring so much additional details most (for example in your case should it not be needed).

[deadoxygen]

Re: Interior render help needed

Point/spot/dir lights slow done rendering, so be careful for mass light scenes. Area lights can be set to "use with IM", that help for more speed too. In your case you could think about emitter materials + a long invisible area light for the whole floor. Add the right floor ground material and the scene could be better looking.

Also for interiors play with the IM subdiv count against splotches. I use 100 ... 200 or more subdivs some times. The IM calculation is quite powerful and fast, you can push it high.

Maybe the starterkit at the forum tutorial section could help you with some hints for the general usage. For example I seldom use IM max rate 0, it slow down the calculation to much and don't bring so much additional details most (for example in your case should it not be needed).

The Almighty Micha! Thanks for your help. I have tried with area light that came with your toolbar. It lits up the interior quite nicely, however, it wouldn't give me any light ray effects I wanted to achieve. How did you do it in your renderings? Could it be possible with only light emitting objects? ie. no point lights?

Thanks for your help!

[Micha_cg]

Re: Interior render help needed

Light ray effects? I'm not sure. At my floor rendering it's the light cone from the spot light. But in your case the walls are quite far away from the light source.

[andybot_cg]

Re: Interior render help needed

The shadows on the ceiling in your rendering are cast by the light fixtures (directly above each light source). One way to fix that is to increase the shadow radius on your omni-light to something like 10.0. That will give you softer shadows, but it does add to rendering time though.