Kray frustration - help!

[larry_g1s]

(modified PM I wrote, but decided to post it in a thread)

ARRUUUUUUUUUUUUUUUUUUUUGGGGGGGGGGHHHHHHHHH Why do I suck so bad at lighting! </rant>

Okay, sorry about that. I just don't get it, I fully admit I don't understand CG lighting. It's the reason why I purchased Kray a couple of weeks ago, to help me learn, but I'm getting frustrated again. I know there is no quick fix, & I'm not looking for one, I really want to learn Kray...I've seen what it can do by many of you on the boards. I just feel at a lost as to where to go. Many of you have been very helpful, and I appreciate the tutorial that Jure had created. But it seems when I try to apply even the same settings in Jure's tutorial (i.e. basically trade out rooms) mine is still so dark. Granted his room has larger windows, but the windows I'm working with are decent size for the room.

I even tried it with a scene from a thread on the NT forum, where again...basically swapped out objects/rooms, used the same settings & everything, and used my room I created (the one I posted on this forum for people to play around with, practice, & learn from one another - found here). What I don't get, is when I did that, I would have thought, I would have got relatively the same illumination in the room...but no. It was still so extremely dark, and I don't know what I'm doing wrong. Any help would be VERY much appreciated.

EDIT: P.s. I've attached an reference image/render. This is what I'm not getting, it would seem like from the light that is on the floor, that there is a decent amount of lighting coming in. Why is it that not much else of the room is very bright?

[Pheidian]

Ok, here's one idea about "what you're doing wrong"... You have Photoshop in your hands? Basic idea of photography as well as CG, is to check your levels in image. I got your image to PS and saw there was practically NOTHING in some points of levels, so I "deleted" them...

Here's attachment of the photoshopped image you sent, even though the GI solution is bit splotchy, you'll see the difference? Also tweaked the colouring little by adjusting the ratios of yellows and blues...

Also a shot from PS, to see what I mean.

You cant always get the results you want by Kray, or any other renderer, that's where PS comes at hand... You can create quick results with Kray that look good, if you just PS them a little...

[weepul]

Learning from other scenes is a good starting point, but even Kray settings ought to be fine-tuned to your own scene.

Lighting too you can learn from other scenes, but here's a tip. It might sound sarcastic or obvious, but here's the thing; to brighten a scene, add more light. Make your environment brighter (use values like 300% for the layer opacity of an additive layer in Textured Environment) as well as your sunlight's intensity. Alternately, use Kray's exposure value; it just multiplies the values in your scene, making the whole thing brighter.

Also, make sure you're using a good amount of Gamma tone mapping (1.8-2.2 depending on your computer) or Exponential (around 3.5-4), or rendering to HDR and toning it in Photoshop or another HDR-capable image editor.

[bigstick]

This raises an interesting question for me. How much have some of the fantastic images we see on the forum been post-processed with Photoshop?

We have all seen some brilliant stuff where people have indicated that no pp has been used, and others where people have posted exactly what they have done to the images. The point then is how hard do you need to try to get lighting right in Kray if you are just going to correct results in PS afterwards?

I really don't know the answer to this, and try to get the best results possible from a 'raw' render. My attached images show this. Some time ago I did a quick, but demanding test with a single area light sun to see how well the GI worked. It is a simplified model of St Henry's Ecumenical Chapel in Turku Finland. There is only a small opening at one end of the scene, and I tried to duplicate the lighting effects quickly. Virtually all the interior lighting is indirect light bounced around, so it's quite tricky. I didn't want to cheat by adding additional fill lighting because I wanted to see how close Kray could get using physically accurate principles.

The raw image isn't really good enough, and I didn't really know where to start to improve it! So out of curiosity I just applied Irfanview's 'auto-correction' feature. I think the resulting image looks a lot better, and for the sake of 5 seconds in Irfanview, I saved possibly hours of rerendering and tweaking lighting and render parameters. Ultimately the final result might still not be as good as the auto-levels correction. I accept that it isn't a finished image, but it was a really interesting exercise for me.

Also if anyone can post any hints on how to approach lighting for this type of scene, I would be interested to hear about your approaches.

[erwin zwart]

whatever works, works for you.
My idea is that it is a waste of time trying to find the right gamma and exposure and tonemapping values before you render a final. I like to render to HDR and tweak afterwards.
That is why I want a postprocess tonemapping window in a future kray. When you are happy with the result of that, kray could render the next tests and final results with those values ofcourse.
For animations it is always better to have a HDR sequence and being able to change all these values in one shot.

[silverlw]

Pshop is god but i have limited knowledge of it so i never use it.
If it's to dark,raise lightsources or Exponential. If windows/lightsources gets way blown out and the room is black anyways i raise photonmultiplier.
I never ever use so called fillights.

[except]

Got a bit of a tutorial that concerns some matters discussed here:

http://www.except.nl/lightwave/hdr

Cheers!

[acidarrow]

Use something like Gamma, parameter 2.2 and exposure 3.5-4 that should fill the room with light better.

[acidarrow]

Okay I download the scene and it's a messy mess. If you are trying to get light in you should at least have glass that is more than 60% transparent and doesn't have any diffuse.

Here is a quick test with the glass removed gamma 2.2/4 and with override surfaces because I didn't want to mess with the materials. It's still a little dark, maybe I should use exposure of 6 or brighter light sources, but I think it's manageable.

[larry_g1s]

Ok, here's one idea about "what you're doing wrong"... You have Photoshop in your hands? Basic idea of photography as well as CG, is to check your levels in image. I got your image to PS and saw there was practically NOTHING in some points of levels, so I "deleted" them...

Thanks Pheidian. As a long time user of PS, I tried that to & it looks good. I just thought that could be achieved in Kray. How would you hand the situation for an animation? Just do the same thing in something like AfterEffects/Express/Digital Fusion/etc.?

The thing that seems to still be throwing me is it seems like I've seen plenty of well lit rooms with not much different settings, or window space for light to come through. I mean, if you look at my scene, the light is shinning right through the those windows, and still the room is not much luminated. I'm waiting for guys like you to take the scene and run with it and see what you come up with.

Lighting too you can learn from other scenes, but here's a tip. It might sound sarcastic or obvious, but here's the thing; to brighten a scene, add more light. Make your environment brighter (use values like 300% for the layer opacity of an additive layer in Textured Environment) as well as your sunlight's intensity.

No, I appreciate it. I did bump up the intensity on the lighting, but it seems like the the suggestion to bump it up in additive layer of the Textured Environment that seems to be help. So thanks.

This raises an interesting question for me. How much have some of the fantastic images we see on the forum been post-processed with Photoshop?

We have all seen some brilliant stuff where people have indicated that no pp has been used, and others where people have posted exactly what they have done to the images. The point then is how hard do you need to try to get lighting right in Kray if you are just going to correct results in PS afterwards?

Which, like I said, isn't a bad thing for stills, but what do you do for animations?

Got a bit of a tutorial that concerns some matters discussed here:

http://www.except.nl/lightwave/hdr

Cheers!

I read your article "Understanding Radiosity in Lightwave 9.2+" and like to say I really appreciate the time and energy it takes to do something like that. I haven't read it sence I've purchased & played with Kray, so it might be advantageous to re-read now. Gonna check out the hdr one, thanks!

Okay I download the scene and it's a messy mess. If you are trying to get light in you should at least have glass that is more than 60% transparent and doesn't have any diffuse.

Here is a quick test with the glass removed gamma 2.2/4 and with override surfaces because I didn't want to mess with the materials. It's still a little dark, maybe I should use exposure of 6 or brighter light sources, but I think it's manageable.

Yeah, I did change those settings. That's why I said in the post, I put the scene together pretty fast and didn't mess with much of the textures & that it was going to have to be done by the user.

Just out of curiosity, why did you take out the glass?

To everyone else who posted, thank you. I'm currently trying some of the suggestions.

[larry_g1s]

Okay, I've attached a couple of Kray renders from JQ that I liked, that don't seem to have huge window space for light entry, yet the rooms are very nicely lit. How do you achieve this?

http://www.kraytracing.com/forum/download.php?id=1355
http://www.kraytracing.com/forum/download.php?id=1356

[darickster]

...

[acidarrow]

I took out the glass because I thought it might become solid if I used the override surfaces.

For animations you generally use a compositing or NLE app. They also usually have tonemapping color adjusting controls.

I believe Johny Quick generally uses photon multiplier of 2-3 possibly Combined with a high gamma value and exposure.

(edit : darickster your suggestion is also possible, why did you delete your answer?)

[larry_g1s]

Okay, here is a re-render. Textures still need some work, but tell me what you think. This was kind of a cheap trick, I basically just took off the wall closest to the camera and toned down the light so as not to completely blow out the room. Then a little contrast added in PS. This is a little more of what I'm looking for, I've just gotta see if I can get it with some of the suggestions mentioned.

[bigstick]

Got a bit of a tutorial that concerns some matters discussed here:

http://www.except.nl/lightwave/hdr

That is a really interesting page, which explains a lot. It must have taken you some time to put together - thanks a lot!