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View Full Version : Color/Lumin Gradiant Bug? Say it ain't so! (using The One Ring)



ChandlerL
04-03-2003, 08:46 AM
Hey all,

I'm attempting to recreate "The One Ring." However, I'm up to the point where I have created the Ring text on the outside of the ring using the bump channel. Everything is working out great.

http://www.myny.us/ring_issue.jpg

Then I want to make the text glow, so I go into the color channel and create a gradiant (WITH INPUT PARAMETER: BUMP). And I assign keys to the gradiant going from hot (White) to Yellow to Red, and finally to the color of the ring in the last key and assign that 0% alpha. The problem is my color channel is showing the text offset from the original bump text: shown here.

http://www.myny.us/ringlumin_issue.jpg

This all shows up just fine in Viper. When I go to render is when I get slapped. What have I done wrong?

I'll eventually be copying the working color gradiant to the luminosity channel to complete the effect... if I can get it to work. The same offsetting issue happens in the Luminosity channel as well.

I've linked the assets into a single zip in case anyone wants to take a look.

http://www.myny.us/RingIssue.zip

Thanks,

Chan

ChandlerL
04-03-2003, 08:48 AM
Hey guys, I figured out mitigating factors of the problem but NOT how to fix it without losing functionality. I've been discussing it with one of the best Lightwavers out there on CGTALK and even she is puzzled. Here is the link to the thread:

http://www.cgtalk.com/showthread.php?s=&threadid=53627

In the meantime, I've resposted what I figured out here for simplicity. Does anyone want to take a look at this? Any NewTek guys out there that can explain? May be I just don't have a full grasp of how Lightwave works with color/lumin channels tied to bump.. I'm really at a loss. At least now I can make the problem happen (see below) rather than grasping at straws.


***REPOSTED MESSAGE FROM CGTALK***

Waaaaait a second here. Leigh I took your advice and re-created the ring-- simple object anyway and lord knows... I need the practice-- Turns out you were right. This time, everything went swell.

As a matter of fact, I was able to complete my entire OneRing exercise without a hitch including all surfacing, glows, etc. Then just a few minutes ago, I went back to it because I wanted to center the letter text a little bit better on the ring-- I jumped into the POSITION tab under the surface bump, and moved the text and lo and behold.. The problem appeared with my new object/scene.

I went back into my original scene (the one you downloaded) and noticed I had originally messed with the texture POSITION in the Bump channel -- that is what is causing the god awful offset color gradiant and luminosity effect. I put all my POSITION elements to zero on my original broken object, and viola, problem solved.. but not really.

*THE TROUBLE IS*... Is this supposed to happen? Shouldn't the color & luminosity gradiants which have been tied to the BUMP channel FOLLOW the X,Y,Z positions of the BUMP channel? It's not as if the gradiants have their own positions one can type in.

Try it on my original ZIP file at the top of this thread, and you'll see what I mean-- you can restore it to working by zeroing out the x,y,z positions under the bump surface, but that means you can't move those positions without the color/lumin channels going haywire and not matching the bump channel.

In the meantime, I can always manually move the text on the texture image itself prior to bringing it into Lightwave, however, I'm sure with much more advanced textures this could cause a serious technical issue.

Lemme know what you think.

Matt
04-03-2003, 03:14 PM
are you sure the bump channel and the bump gradient parameter are supposed
to be tied?

according to the manual, regarding the bump gradient parameter, and I quote . . .

"Bump uses the height of surface using layouts default unit
on the general options tab in the preferences panel"

doesn't say anything about the height of any bumps map applied to the surface.

or am I reading it wrong!

according to that also, it means if you have a gradient with a bump value of
1.0 and your default units is set to metres it means it's 1m, but if it's millimetres it's 1mm?

If so that strikes me as kinda stoopid - tying surface settings to a general preference that will be different
on everybodys machines!!!

ChandlerL
04-03-2003, 03:38 PM
I completely hear what you're saying.. But here's the way I'm thinking of it. If I move the position of the bump texture. That moves the gray scales (white to black). If the gradiants are tied to the bump, shouldn't that mean that black areas have 0 gradiant and white areas, 100%? In other words, it would "follow" the bump wherever you moved it because the white/black/grays would move with the bump and therefore, the gradiant effects would be forced to move with it.

Matt
04-03-2003, 04:14 PM
as usual the manual totally doesn't explain it fully!

did a test . . .

http://www.creactive-design.co.uk/misc_images/bump_test.jpg

it's a bump map in the Y axis of a planar map.

the colour / luminosity channels are set to gradient->bump.

did two renders and moved the bump map, everything seems okay.

wonder if it's a cylindrical mapping thing?

ChandlerL
04-03-2003, 04:20 PM
Interesting observation.. You're gradiant looks just fine and matches up. Have you tried it with a cylinder? Two heads are better than one. Can you recreate the problem with a cylindrical map?

Matt
04-03-2003, 04:22 PM
aha! found it!

it appears to be a bug only occurs when using cylindrical mapping!

better report that one asap!!!!

http://www.creactive-design.co.uk/misc_images/bump_test_cylindrical.jpg

ChandlerL
04-03-2003, 04:27 PM
Sure looks like it! Thanks Matt. At least I know I wasn't crazy..

... Or right.. May be I still am.. But I'm not crazy when it came to this. :rolleyes:

Matt
04-03-2003, 04:29 PM
cubic mapping is fine, but it doesn't like spherical either . . .

Matt
04-03-2003, 04:32 PM
:rolleyes: :mad: :eek:

hunter
04-03-2003, 05:34 PM
Hi,
I don't like bugs either so I downloded your file and made a cylindrical UV map and used it.
Maybe less of a headache for ya.

ChandlerL
04-03-2003, 05:35 PM
Did you try altering the position of the bump maps by adjusting the x, y, z coords?

Try that and see what happens. The gradiant and luminosity channels will not follow creating a ghost image offset from the bump.

If you already have and it's working, then let us know what version of Lightwave you're using.

Matt
04-03-2003, 06:01 PM
hunter has a point, it might work with UV mapping, didn't try that, did think of it though!

ChandlerL
04-03-2003, 06:08 PM
Holy potatoes.. Sorry hunter.. I read your post so fast I didn't even realize you said cylindrical **UV**... oops..

That is an interesting point then.. If you UV it, the problem goes away.

At least we're zeroing in on the issue. We'll have to see what Deuce says.

hunter
04-04-2003, 11:01 AM
Hey,
No need to apologize:) I've been tweaking your scene a little more. This was done using 2 rings, each with your bump pic used as a clip map but inverted on one. So, one ring renders only the writing and the other only the ring (minus writing). This way you can set the glow intensity differently on the writing and the ring. BUt of course it now needs to be called Lord of the Two Rings. ;)
Sorry. :rolleyes:

ChandlerL
04-04-2003, 11:06 AM
*chuckle* Lord of the Two Rings? Poor Frodo.. :p

Very nice, hunter. Can you post up that object/scene? I'd like to study your surfacing and also how you used two rings for that effect. Never even thought of that and yours looks tons better.

What I've been working on now is making the ring look more like gold (a non Lightwaver said mine didn't sit right in there eyes as a gold ring - I think this new one gets closer to the mark)

http://www.myny.us/ring_moregold2.jpg

hunter
04-04-2003, 11:41 AM
Yea, I think that is looking a bit more like gold. Here is the zip. I was also trying the effect with volumetric lights in the 03 scene, but it seems more trouble than it's worth.

ChandlerL
04-06-2003, 01:20 PM
Hunter,

Did you by chance send me an incorrect file? I was studying what you sent me and I don't see the two ring objects, only 1. And my F9 render doesn't look like the image you posted.

May be the wrong file?

Anttij77
04-06-2003, 04:28 PM
I tried out the scene, and it turns out the object is scaled down to 0.246 in layout.
If you reset the size to 1.0, the problem goes away...
Funny thing is that it appears when the object is scaled down, not when scaled up...

ChandlerL
04-06-2003, 04:58 PM
This is an interesting find. I'll pass this information on to Deuce over at Newtek

hunter
04-07-2003, 09:56 AM
uh, yea, looks like some of the scenes weren't zipped properly. hmm? let me try again.
I checked. This one seems to work. Load the onering02 for the image I posted.

mattclary
04-15-2003, 06:54 AM
I liked this tutorial!