PDA

View Full Version : I want to improve my wall!


Tommi
11-26-2003, 08:18 PM
Hi there...

I haven't managed yet to do that blood splash effect, but here's
another take from our assignment film
("Tracer Bullet" ... slightly inspired by a Calvin and Hobbes comic
strip)...

It's a compositing shot which consists of three layers and
in particular I want to improve the Lightwave-rendered part
of it, but I'm stuck, because that's beyond my current skills.

Here is a total view of the object I want to make better
(probably texturewise :shrug: ) - I want it to be as realistic as
possible :hmm:

http://home.tiscali.de/tomkater/tb_mauer.jpg

I've increased the gamma to 1.3 in an graphics app.
For compositing I'm using After Effects 5.5 Production Bundle.
In the following video, you can see, that I've modified the CG
wall - I darkened it, changed the colors and I added a glow
effect; probably I'll remove that again, but I'm waiting for your
comments and ideas...

Tracer Bullet - wall shot (DivX appr. 4.5 MB) (http://home.tiscali.de/tomkater/mauerfahrt.avi)

I'm looking forward to your suggestions :)


P.S.: I think the image above and the video are very likely to be to dark on your monitor. In this case I apologize in advance... I decided for that level of brightness due to a couple of tests on some monitors (CRTs and TVs)... But maybe it's really too dark, I'm not sure about that...

Tommi
11-27-2003, 09:36 AM
Pew... almost 100 views and no reply... :surprised
Maybe I should be more specific with my question(s)...

I think the wall looks a little bit sterile and the water may not be the best solution arround.



- Are there any tips, hints or shaders for texturing stone and walls


- is there a way to project an animated procedural texture with a spotlight? I am using a rendered image sequence for the wall


- for the stream I'm using animated displacement procedural textures. I'm not quite satisfied by the result, but I currently can't say what's wrong with it


and here comes my general problem:


- I've been working too long on that and I feel that it is not good enough, but I cannot determine a reason, yet. Do you have any ideas?

SplineGod
11-27-2003, 09:23 PM
I think you need to add some specularity to the walls so thy look damp. I also think you need some kind of light source and then some caustic bounce off the water onto the wall. You can fake the caustics by projecting a texture thru a spot light.
Im not sure if thats a reflection of the wall on the water or we are seeing the wall under the water. Either way it doesnt look quite right. :)

Tommi
11-27-2003, 10:14 PM
Thanks for your reply, SplineGod :)

Believe it or not - there indeed is a caustic effect projected by a spotlight :D I assume that the effect isn't that visible...
Thanks for the specularity hint - for some reason I haven't thought about it, yet, because I was just thinking about darkness and making everything dark.

I have used caustics calculations on that scene a couple of times before. For some odd reason I did not manage to make the effect bounce off the water surface onto the wall. Neither the spotlight above nor a spotlight placed below the water (and pointing at the wall) made a caustics effect for me :(

The wall just continous a tiny bit below the surface, I actually don't know why the reflection looks that off.


By the way - I already tried to make use of a painted weight map and gradient textures as well to make the wall close to the water surface look wet and smoothly fade into the dry stone surface above. I couldn't manage to do these settings. I still don't get gradients, yet

SplineGod
11-27-2003, 10:52 PM
Focus on one thing at a time.
Everything has some amount of spec.
It would probably be more specular/damp near the water and probably in the joints between bricks.

You could do the castics a number of ways. One would be to project via a light. If your diffuse value on the walls is low it may not show up readily. Another would be to apply the water procedural to the wall in the luminosity channel but mostly near the bottom of the wall where it hits the water. You can use a weight map with a gradient to make it falloff. You do this by adding the gradient on top of the water procedural in the luminosity channel. Make the input parameter of the gradient be weight and then tell it which weight map youre using. Next set the blending most to ALPHA. The idea is that youre using the gradient and weight map as an alpha to blend out the water procedural.

Change the color of the water to a very dark blue, almost black.
Apply a gradient to it in the reflectivity channel with incidence angle as the input parameter. In the surface panel for the water surface play with color highlights and color filter under the advanced tab. You typically want reflections to be some value lesser then the actual surface you are reflecing in the water.

Add a main light and get your lighting on the wall to work and then add any additional fll lights to get the look you want. Use falloff on the lights too.

Do each thing one at a time so you get a feel for what youre doing. Its easy to become confused when adjusting more then one thing at a time. :)

rickycox
11-27-2003, 11:11 PM
There's very little contrast in the image. I like the brickwork on the top section, but the bottom section looks a bit cloudy. You should probably try to get you lighting right before you worry about textures though.

fig
11-28-2003, 01:33 AM
well, this may be more related to art direction but i look at it and i'm not quite sure why the wall is surfaced the way it is. the stone up top then brick doesn't quite make sense to me.

anyway, one thing i'd probably do is completely change the surface underneath the brick that's broken away, make it higher contrast or a different color entirely. don't be afraid to get the entire thing dirty and marked up either, if you go look at a wall downtown or a drain somewhere you'll probably be surprised at the the range of color and texture you see there. put some dirt and grime into the cracks of the brick and stone (there should probably be more contrast there to start with, the mortar between the stones is a totally different material), make some water or rusty-looking stains on the wall, anything to give it character. the caustic reflection looks a bit procedural at this point and doesn't really read as a reflection yet, just looks like the pattern on the wall (may be because its not animated). keep going tho, it'll get there :)

chris

Tommi
11-28-2003, 10:16 AM
Thanks so much! I really appreciate your help :)
I'll work on the scene immediately and post an update...

@SplineGod: your tips are invaluable as always :D

@riki: I'm glad you like the brick pattern - I used photo references of a real wall at the place we were shooting some scenes for our short film.
I traced the single bricks in Flash (because of the ease of use), imported the structure into LW, extruded and beveled each brick. That was the most tedious thing I've done in LW so far...

@fig: I think I answerd your first question above :D - I used photo references and I tried to mimic a rather ugly wall...
Thank you for your tips, I'm going to work on it now

Tommi
11-28-2003, 12:01 PM
Okay, here's the update. I worked on the light - two spot lights in front of the wall.
I tweaked the textures and tried to fiddle around with gradients, but I still need to figure that out :shrug:

http://home.tiscali.de/tomkater/tb_mauer_2.jpg


The strange pattern on the lower part of the wall is due to the water texture in the luminosity channel. I need to improve that somehow :hmm:




EDIT:

Okay, I'm currently working on the caustics effect. I put the procedural into the luminosity channel and above a gradient, blend mode set to alpha with input parameter "weight map". I created a weight map called "falloff", which fades from 0 % at the very top of the wall to 100 % at the base.
I don't know why, but this falloff weight map doesn't affect the gradient in any way. I tried several settings and even changed the weight map several times, but I can't see any changes. The current result is an overall overlit surface.
I'm just guessing, but it appears to me as if the input parameter "weight map" doesn't work for gradients :hmm:


2nd EDIT:

I could get the falloff to work, but somehow I still don't get how gradients work. Strange thing is the -100% offset of the very first gradient key...
Currently I'm not satisfied by the motion of the caustics. For the water surface it works, but not as a projection on the wall. Need to tweak that an than I'll do a further update...

SplineGod
11-28-2003, 08:36 PM
I think this is a big improvement so far. :)
Heres a weight map I used to limit the fake caustics down towards the bottom.


HERE (http://www.3dtrainingonline.com/examples/fake_caustics.avi) is an example of using the underwater procedural in the luminosity channel and then limiting where it effects the surface by using a weight map.

ASCIISkull
11-29-2003, 05:41 AM
One thing that is very noticable is that the water is flat where it meets the wall. Also, maybe having a darker area where the wall would actually be wet from lapping water would help.

Since the bricks and stones are actually modelled, you can use radiosity(or even a accesability shader) to create a texture map for the crevices in the wall, which you can then use to apply dampness, mold, or whatever between the stones.

What kind of lighting will be used in the final shot?

Tommi
11-29-2003, 10:04 AM
Thanks again for your replies...

@SplineGod: It works :)

@ASCIISkull: The scene is supposed to be "shot" at night, therefore I try to make it appear so. The current light setup consists of three spot lights. You're right about the water, I'll try to improve that. Before using the gradient & weight map technique, I tried to do something like a wet area of the wall - I created a surface and applied it to the lowest row of bricks. It looked a little bit awkward, because I didn't know how to make the shiny water effect fade out. I'll give it a try today :)

At which AA-level should I try to render radiosity?

SplineGod
11-29-2003, 10:27 AM
Hey Tommi,
Glad that part worked out. :)

CGTalk Moderation
01-16-2006, 06:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.