Help with a cup

[webshot]

looks like you got hdri grain in there. I just asked this question and got some good answers if you search the boards for "hdri grainy" you will find my thread.

[blaqDeaph]

What lighting do you currently have set up?

[Xristot]

I have one area light and 3 distant lights. Only the area light is casting a shadow while the others are just for general lighting purposes.

Thanks webshot. I remember seeing that thread but I wasn't sure if it was the same problem. I'll check out that thread again.

[Xristot]

Ok, I followed the advice given on spinquad and so far I got the image below. The bad artifacts are gone and the glass looks a lot smoother. For this I basically applied HDR exposure to the HDR backdrop and applied a blur to it as well. I still don't know how to get it completely clean. I don't know if its the polygons or the ray recursion limit or anything. Any help would be appreciated.

http://img.photobucket.com/albums/v239/Xristot/cup_better.jpg

[webshot]

yup I was going to say do that, but it was explained in my thread. I had that exact same problem. I also used hdrshop to edit things a bit more and it came out alot better.

[Xristot]

i just am wondering how to get rid of the those problems I still have on the edges. I don't know why I'm getting them. Thanks for telling me about hdrshop though. It looks useful.

[akademus]

Maybe setting your AA to higher level will take care of edges (if I got your problem right). You can also play with new PLD antialiasing if you have newer LW version.


greets

[Xristot]

Higher level AA did not work. I've tried a lot of things. I am now using gradients instead of fast frensel but its not helping much. I am rendering a shot that is really close up to see the noise better. Ill put it up when I get it rendered.

[Ayreon]

Under processing tab (ctrl + F5) check Limit Dynamic Range and see if that helps. Helped me out a few times!


Ayreon

[Xristot]

I turned on limit dynamic range but for some reason it is still not working. I got a close up picture with low AA turned on to see the grainyness a bit better. Here it is.

http://img.photobucket.com/albums/v239/Xristot/glass.jpg

I don't know why it looks like that. I'm really at a loss about how to fix that. Maybe its my model...

[akademus]

if you are replacing fresnel shader with gradients i highly recommend tutorials from Worms of Art. It's great explanation of how fresnel effect works. Check it out on http://www.the-worms-of-art.com/

[blaqDeaph]

Try increasing the Ray Recursion?

[Xristot]

The only problem with ray recursion is that it drives up the rendertimes. But, I did bring it to 24 and it wasn't helping. Thank you everyone for the help so far!

[Ultimatum]

Try adjusting the gamma in Image editor for the HDRI image. It sometimes helps.


- U

[RPG2006]

Rather than adding and upping settings, you could try to remove a few to isolate the problem.

Maybe try removing the hdri image, and see what it looks like with a simple gradient backdrop. Is the grain still there?

Try removing all the lights except the area light and exchanging the area for a spot or distant light. Again can you still see the grain?

As you've said yourself it maybe the object. So you could try replacing it with a simpler glass object.

I've spent days in the past experimenting with this sort of thing. Quite often when I've been struggling with results I end up stripping the scene bact to it's bare basics and having another go.

There are quite a few tutorials out there. My personal favourite and one I've posted a few times is the jack daniels bottle and glass tutorial.

With regards ray recursion, I believe 24 is way too high. When it's too low, from experience you tend to get dark areas, where the light is not bouncing around enough. Much like yourself I have found that over a certain point the only thing increasing is the render times, rather than quality. In the tutorial I mention above, his results are very good and if I remember he uses a ray recursion limit of between 6 and 8.

Here's the link by the way.

http://www.liquid-arts.de/techniques.htm

RPG:)

[Xristot]

I have run through that tutorial actaully. Its a very good one.

Going to what you said, I have been stripping the scene down to the basics. I took the HDR image off and was playing with a few objects. I still have yet to get a good solution. I'm still going to work with it though. Thanks.

[Xristot]

OK, I did some tests and changed some values around. I changed the area light to a spot light and got the following results. It looks like I wanted it to now, but there is still grain on the sides. This image was made with low AA and a ray recursion limit of 10. I lowered the gamma on the HDR image, added HDR exposure to the HDR image with a white point of 1.15 and I added a full precision blur to it as weel. I don't know where that noise is coming from though. I made a very simple cup and was still getting those results. Maybe I should build the mesh from scratch again? As you can see the center looks perfect...but its on the sides where I am getting that grainyness. Thanks for all the help again.

http://img.photobucket.com/albums/v239/Xristot/whereistheproblem.jpg

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