Render issues

[kdarius]

Hello all first off let me say i love Indigo. I instantly baught the licence when i saw the new version come out. I am having some issues though. I know the longer you leave it to render the clearer the image gets. Usually i will let it sit overnight but I still can not seam to get ride of the grain.

I have a dual quad core xeon 2.49 processers. 2 quad cores
With this much power i should be able to knock out great looking renders in no time.

In the image i have attached you can see the grain i am talking about..
I look at the website and see these crystal clear renders and that is what i am shooting for.

any help would be great.
thank you

[StompinTom]

You're using a lot of glass. That takes ages to clear up.

- What resolution are you rendering at?
- Are you using Metropolis? Bidirectional? Both?
- How long did this render for?

One option is to render at hi rez and then scale it down after rendering. I'm guessing that the images on the front page look so clean because they were actually rendered larger. Other than that, don't use pure !00% colors (keep everything below 0.8, 0.8, 0.8 or so).

Hope that helps...

[kdarius]

The effect i was going for was not glass. I wanted to be semi transperent to see the assests underneath the tent. I did this by using a blend with a Phong and null.

The rendered is set to both Metropolis and Bidirectional both being on.

The image i posted ran for 3 hours. Which would be a long render time on a regular dual core machine (12 hours).
I has 1500 samples.

I rendered it at 1280x1024

I have never heard of the 0.8 0.8 0.8 would this really effect the noise issue.

It has helped when i have rendered something double and then reduced the size but is this something i need to do everytime? Maybe this added info will help solve my problems.

[Soup]

It is because it's mostly beneath glass. But because your scene is quite simple, and the glass doesn't have any absorption effects or anything like that, try the 'ghost glass'. That should help a lot because it's quite simple.
If you wish to keep a more realistic glass, turn metropolis (MLT) on, it should help stop the glass being an issue.

[kdarius]

Can i change how transparent Ghost glass is. I want to see the outline of the tent. Like i said earlier i dont want the tent to look like glass but just somewhat transparent so people can see what is under the tent. Also Metropolis is already on.

[Soup]

Sure, the Ghost glass is a Phong blended with a Null material. Change the blend amount to change the 'opacity'.

But if you're not after glass exactly, maybe make a material for the outside of the tent, and then blend with a Null to add opacity.
Or you could make a mask to create the cut-away effect (same as as above, except using a 'blend map':

[Meelis]

You may turn off cauchy_b_coeff for some speed up, if u used it for your glass.
----
EDIT, u didn't use glass, sorry my bad.

[StompinTom]

Guys, he said twice that he`s not using glass already.

Can you post the full rez rendering? 3 hours isn't that much, even with dual quad cores. It takes 20+ hours sometimes for me to get decent results with large images (~3000x3000) with my quad, and even then there's still a bit of noise.

Having materials below 0.8, 0.8, 0.8 will help a lot, the noise should settle quicker. In real life, perfectly white paper only reflects about 85% of light anyways, so it doesn't make sense to go above that.

[kdarius]

Thanks for all your help guy i have to change a couple of things to the layout and am going to rerender today. I will upload a update later. The ghost glass did work pritty well. If i just want to turn down the opacity of a metterial i have to use a blend with a null right?


Thank you

[Soup]

Yep that's right. The blend amount becomes the opacity amount.
StompinTom's right, the white floor will probably be reflecting too much. Change it to 80% white, and mess with the tonemapping later to make it white.

[kdarius]

Hey Guys this is where i got this morning. I really did not get a chance to render it that long. The Ghost glass looks great. I think when i started following the .8 .8 .8 rule also has helped.

Thank you for all your advise. I know its not that great but i only had 5 hours to model and texture and only a little bit longer to render. But will work great for its purpose.

[galinette]

kdarius : You should also try with an envmap instead of the skylight. Then enable MLT, disable bidirectionnal. It uses to be much more fast to render glasshouses. I'm currently rendering a lot of glasshouses with tons of insulating glazing units (2 glass panes separated by air, meaning 4 interfaces) and this works much better than skylight. That's also looking more natural regarding shadows.

Etienne