CGTalk - Highlights problem

Pate

03-04-2003, 05:42 AM

Hi!

I have a bit of a problem trying to use the R8 Highlights post effect on a scene.

My scene has a metallic object in the foreground for which I want to use the highlights. The problem is that I also have a background that has some bright areas, which seems to confuse the highlights post effect.

First I assigned my metal object to an object buffer and told the Highlights effect to only use this object ID. This helped a bit (no bright background areas far away from my metal object got highlights), but I still got highlights from a bright background area that is very close to the visible edge of my metalic object, even when my object is very dark (in shadow). Does not look nice.

Do I need to use multiple passes to get the post effect to behave? If so, how would I do this? I have not needed to use multiple passes before, so I don't quite know what is the best way to do this... Any pointers?

Or is there another trick I can use to really get the highlights only for my object?

TIA!

Pate

Per-Anders

03-04-2003, 05:54 AM

your metalic object, is it reflective? if so bring down it's reflectivity a bit rather than darkenning tha actual metal, thatn should sort out the "egde" highlights, failing that you can increase the tolerance of the highlight together with having two lights fo the scene, one for the foreground metal object that's much brighter than the one that's for the background only (use include/exclude lists in the lights). that shouls olve hte problem for you.

Pate

03-04-2003, 07:35 AM

Thanks mdme_sadie for the fast reply!

I tried turning off reflection but that made no difference. I'll see if playing with the light exclusion/inclusion has any effect. Not sure if that will help either as the background nebula is luminescent and has no lights illuminating it at the moment.

I thought I'd include a screen shot as well. The top part is with highlights. It is supposed to be a spaceship in front of a nebula (still very much a WIP, part of an animation I am working on). The highlights on the nose of the ship (though exaggerated here for illustrative purposes) is what I am after, and would like to get rid of the highlights over the nebula.

Pate

Per-Anders

03-04-2003, 07:44 AM

ok, you're going to have to increase the strength of the rimlight on the spaceship some, and also increase the spaceships specularity a bit too, the higlight filter needs something bright to actually highlight int eh first place.

it's odd that you're getting highlights from the background even though object id is turned on, if i were you i would send that file to maxon support as it sounds like a bug that needs to be fixed imo (so send them the uneditid version where it really shows up).

Pate

03-04-2003, 07:56 AM

Heh, thanks for the suggestions mdme_sadie, though I'm not worried about not getting enough highlights at the moment. I'd just like to get rid of the extra highlights! :)

I'll see about sending the file to Maxon Support. I thought this looks like a bug myself, but I've thought so before and then found out I had done something wrong, so I wanted to check here first.

Thanks for taking the time to help!

Pate

Wilson-3d

03-04-2003, 01:44 PM

Hi. I am working with a scene some post highlights also. The lighting set up is finished and I Don't want to use exclude or include for the highlights b/c I already am in the set up. I just want one item in the scene ( a chrome toaster actually) to have the highlights. I have them looking just right on it but everything else is giving them off also. I gave it a composit tag and an object buffer and then assigned the highlights tag to object buffer 1(which matches). Is this what you ment mdme_sadie when you mentioned a bug? I think this should be working but perhaps I did not interprete the manuel right and you only use object buffers with highlights when you have more then one settings. I think this is what I should do if I only want one object in a scene to have the post effects highlights.
Thanks for any commenets. Just thought I would post with this one because I am haveing the same problem.

Pate

03-04-2003, 03:00 PM

Just to let you know, I sent a simplified scene file to Maxon Support. I just got a reply saying that there indeed seems to be a problem and that they are investigating the cause.

Interesting!

Pate

Wilson-3d

03-04-2003, 03:59 PM

Thanks. If you have time let us know what they say.

Srek

03-05-2003, 09:26 AM

Hi,
it seems you are using Anti Aliasing on the scene. This will "Smear" Color of sourounding objects in your to be highlit object providing additional bright spots n the object. I can see no way to prevent this other then not using AA or doing it via compositing with two renderings.
Regards
Srek

AdamT

03-05-2003, 12:58 PM

Of course you could do it the old-fashioned way: render at a multiple larger size and batch resample in PS or AE.

Pate

03-05-2003, 01:01 PM

Ah, thanks Srek for the tip!

Not using antialiasing is actually a viable solution for me, as I plan to use scene motion blur anyways. I just hadn't thought of that when test rendering my scene..

I just tested the scene without AA and now the highlights work beautifully!

Thanks!

Pate

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