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Carrara F.A.Q (Last Updated: 2024 Nov 28 3:44 pm)

 

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Subject: Glass and bottle WIP


marcq ( ) posted Thu, 24 July 2003 at 9:06 AM ยท edited Thu, 14 November 2024 at 2:05 AM

file_68492.jpg

Here's a current WIP I'm working on. The glass, bottle and wine are modeled in Amapi7 (and use the importer without incident). The floor and walls are just for test purposes. I'm playing around with the shaders in these test renders.

I wanted to post the WIP in case anyone wanted to offer some suggestions but also because it illustrates something Jeremy Birn mentioned in his great book "[Digital] lighting and Rendering".

In the first picture, one of a number o fissues is that the far lip of the wine glass seen through the near edge of the glass is rather indestinct. Jeremy mentioned that often the issue is not the lighting or shader but the model itself. In this case one of the problems is that I forgot to add a rounded lip to the wine glass.

Marc


marcq ( ) posted Thu, 24 July 2003 at 9:08 AM

file_68493.jpg

So I added a lip. It helped a little but not as much as I wanted it to. So I started experimenting more with shaders.


marcq ( ) posted Thu, 24 July 2003 at 9:14 AM

file_68494.jpg

In the current WIP, I added a fill light that doesn't cast shadows (for a second set of highlights) and played around with the highlight channel.

I'm not satisfied with the shaders yet but my thought was to broaden the highlight. I still wanted the small bright highlight to indicate glass but I was looking for some broader color to help show the shape of the glass.

So I used Mark D's iridesence shader to create a highlight that has a small white spot where the two lights create white spots and then a broad, dim color region. Not really satisfied with the result yet but I think the technique is promising.

Things I'd still like to fix (and would love suggestions on): The caustics for the glass base are too bright. In my actual scene, the arrangement will be such that this is probably not an issue. But any ideas on adjusting this?

The bottle shadow's internal detail is too crisp. Is there a way to blur this (without CS3-beta ;-)? I'm using GL with indirect light and caustics.

Marc


EMC ( ) posted Thu, 24 July 2003 at 10:14 AM

I agree with you on the shadow cast by the inner part of the bottle being too crisp. I might not be the entirely wrong look, but the difference seems to thick (i.e. the glass may be too thick, which makes that seem unsightly). Besides that, all the wine glasses I drink out of are clear, and don't really have any color what so ever. I did a scene with your average wine glass and bottle in Raydream St. 5.5 a while ago, and it can really be a pain to get right. EMC


marcq ( ) posted Thu, 24 July 2003 at 10:39 AM

I may have to do a post-render blur on the bottle shadow if it is a problem in the final scene. On the glass color, the scene will be a fantasy scene with some faeries and a rustic appearence so hopefully an off color in the glass won't look odd. I'm still experimenting with a subtle glass irregularity in the bump channel (there is a ripple there now but it is probably too faint at the moment.) Thanks! Marc


mykael ( ) posted Fri, 25 July 2003 at 9:06 AM

What happens if you turn soft shadows on? For the high lights, try adding a long, glowing, white rectangle off screen towars the camera. Hopefully it'll generate a long high light running along the length of the glass to show off its curves. You might want to consider adding a vertical one for the bottle. Mik


marcq ( ) posted Fri, 25 July 2003 at 10:07 AM

Tnanks, Mik. Good suggestions.


marcq ( ) posted Sat, 26 July 2003 at 7:44 PM

file_68495.jpg

A little too blurry on soft shadows but better. I'll try a lower blur next go-around. I'll experiment with your lighting suggestions in the final scene; they sound quite useful.

Marc


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