GI project in progress

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Old 03 March 2006   #1
GI project in progress

Hey everyone
This is my first real GI attempt using EIAS 6.5r2. I am happy with some of the results and not so much with others. There is obviously a lot for me to learn. I was hoping that this forum would be a good place to learn and hopefully help others who are unfamiliar with EIAS GI understand better as well.

The image: The image is a jungle ruins concept. There is a lot to be done in this image, not just GI tweaks. More texturing and some modeling fixes. The 2 pillars in the middle of the screen for one. There are some faceting problems there. So critique what you will but I'm mostly interested in getting this GI render time down. I have heard EIAS's version of GI is fast. Well, I'd like to see that speed. This image took close to 3 hours to render on a 2.1ghz G5 with 2.5 gig of ram. That's too slow for me
After I try out any tips I receive, I will post updated renders and render times so that everyone can see what the differences are in speed and image quality.

So, if you have tips and rules of thumb, please share with me and the rest of the EI community.


Old 03 March 2006   #2
Hi Richard,

Thats a really cool image! If you share the project stats and your GI settings i'm sure you'll get some helpfull responses.


"I'm full of dust and guitars"
Old 03 March 2006   #3
thanks Nige
Yeah, the image is very big, so you have to expand your window out horizontally. The project info is actually under the image, you have to scroll down to get it. Sorry , I should have put this info at the top of the page. I'll do that for future renders.

Thanks again Nige
Old 03 March 2006   #4
Hey Richard!

The look is absolutely superb!

About your settings:

Primary rays: 200 looks good enough at the moment.
Secondary rays: Turn these off (0), this type of scene really doesn't need them, dun dun duhhhh, half an hour of your render time (probably more!)... that was easy

Sampling level: I'd change this to 8x8, 16x16 is faster but it isn't as sharp. Is your anti-aliasing set to Averaging? The ground especially doesn't look very sharp, that might be the texture though.

Bounces: The general rule here (although break it when ever you like) is 1 bounce for outdoor scenes, 2 for indoor scenes. This, again, will knock another chunk of time off the calculation (possibly another half hour or more).

Everything else looks dandy, so, have a firm handshake from me for a GREAT image so far !!!

PS. Are those shadows being created by a gobo or by geometry...?
Old 03 March 2006   #5
Nice job. The cast shadows of the plants look great.

It's hard to be too sympathetic about the high rendering time--to look at your setup, you've got every render hog in the book (multi-bounce GI, dome lights, hi-poly plants) in there. I'm actually amazed it only took three hours to render. If you want to cut down on the render time, I'd suggest:

A. reducing the bounces to 1, or even 0.
B. Using a lower GI sampling level.
C. Not using the illuminator dome.
D. Rendering the plants on a separate pass and doing the cast shadows with a gobo.

Old 03 March 2006   #6
Hi Richard,

Finally you found your way here...
you have missing for quite some time, must be very busy.

ok! back to the topic... that is very nice image you have done, vert impresive,

my GI setting

1. always set the secondary ray to 0, you can add another light set the GI mode to secondary, for the same (?) result with faster render time... especially with transparent object.

2. bounce light to 1, ant number above 1 won't help a lot, but cause render artifacts.

3. I see you use the old Illumiantor doom together with GI, try avoid that, i think it will solw the rendering because it need to calculate 17 times in your sample... since you use GI sky light, maybe you can increase the density a bit

4. try to avoid very small polygons sitting together in your model (see tumbnail), I think the only solution for this is faster machine and more RAM hehe

I'm still usung a very old machine, this tips help me quite alot...I learn from the expert, I think there might something else I have not discovered... any one?

Attached Images
File Type: jpg sample.jpg (24.6 KB, 76 views)

Last edited by yhloon : 03 March 2006 at 03:45 PM.
Old 03 March 2006   #7
Thanks Ian
Great tips! First, it should be noted. I jumped into the deep end after just glancing over the documentation. In the past EI's docs haven't been the best so that's why I just dove in. I plead ignorance on the secondary rays
The ground texture is actually hi res so your settings change may make a big difference, I'll check. Plus I beleive the displacement was too much and made it look bubbly. I have fixed that, looks much sharper now > see link. I am using adaptive antialiasing, that always looks sharper. I will also lower the bounce number. I will post a new render soon. Oh, and the shadows are mostly low res geometry. I do have one shadow casting tree that's off screen. I have never been able to find a good leaves image to use for a shadow map. Any suggestions?

Again, thanks Ian for the great tips.
Old 03 March 2006   #8
opps my reply are a bit too late...

one more thing, if you are using RT shadow transmission to the leaves, try use the tradissional transmission...


Old 03 March 2006   #9
Hey GM
Thanks for your input. Yeah, I knew I was doing stuff wrong, hence my involvement here
I will be reducing bounces and cutting off secondary rays. I will try eliminating the light dome, but the image was a little too dark for my taste with out it. I like the "hot day" look. I will not be doing any post work on this image though. This image WIP is to see what EIAS is capable of in a one time render deal. If it was part of a paying job and there might be fixes coming from a client, yes your right on the money. I would be doing this image in several passes.

Thanks again Giacomo
Old 03 March 2006   #10
How you doing? Yes, been quite busy as of late. Got some character work I'll be showing here soon. I need some feedback on that as well. It's been so long since I did a real render in EIAS, so I figured I'd do this project to refresh my skills. My character stuff has been more cartoony rendering styles.

Thanks for the tips. Indeed, I have been very nooby about the EIAS GI.

I didn't realize the issue with small tightly packed polys. Luckly, most of this image is using relatively low res props, except for the bushes.

And yes, I'm using raytraced shadows. I tried using buffer shadows but got spoiled with the look of raytraced shadows in this image. I think that answers your question.

Glad to be here Loon!
Old 03 March 2006   #11
Slap me if I start to be patronising!

Ahhhh, fabtastic.

That ground looks absolutely exceptional, one wonders how you came up with that great texture (not only one, but me too). If I'm to be hyper critical, I'd say turn the bump down slightly, it's messing a little with the ultra dark shadows.

I'm sure you know this, but with your anti-aliasing try setting both boxes to 255 (on averaging mode). That makes camera automatically 'mackie line' the render, which makes it even sharper still.

Stick with the illuminator man! Ignore loon hehehehehe, I have found it useful to combine GI and Illi domes in certain scenarios, and in this scene I would use one (or a light rig).

If you start to lose colour depth in the image then you have probably set your sky light too high (but 0.55 is great).

I think you have had trouble finding good tree gobos because there are none ! Total Textures have a couple of acceptable shadow maps but nothing beats the real thing...

I'd like to know your Sun shadow settings (light size, samples, and distance to reference).
Also, what's your scene scale (one granger unit = a cm etc).

Ace work, I'm jealous

I'm amazed at the pace of this thread! Great stuff, right back to my beer and painting my speakers

Last edited by halfworld : 03 March 2006 at 04:05 PM.
Old 03 March 2006   #12
Yeah, I love this texture. I bought it from .............. I can't remember. But I got a full cd and all of them are great. I'll try and find out where it's from and post it for you.

I will lower the bump a bit more, I think your right there.

I really like the skylight option. And yes, I really like the GI dome but what I'll do is render one with and one without. I'll see if the render hit is worth it. I'll post both.

Yeah, I prefer geometry gobos personally. Always seem to look better.

I have messed with the alis boxes in the past, but am unaware of what mackie line is? Enlighten me!

Light settings for main "sun" light:
Type: Spot Light
Intensity: 1.455 > This setting is nice and bright and doesn't blow out areas too much.
Size: 2.0
Shadow: Raytraced, soft edge enabled= Light Radius: 1.0, Samples: 12
Optimize Shadow enabled
Light to ref distance: 400

The scale is what ever EI defaults too I guess. Honestly, I never mess with it. Suggestions maybe?

Oh, and the pace may slow down a bit as I have to render

Thanks man
Old 03 March 2006   #13
Originally Posted by DickM:

So, if you have tips and rules of thumb, please share with me and the rest of the EI community.



Hey great image !

Ok, my suggestions, some already mentioned..

If you are using a soft edge on the RT shadows (which it looks like), i would turn the soft edge sample level down to about 7.

GI, i would really try and do without the illuminator, as you know, 1 sample= 1 light and with all those lights incuded in the GI calculation its gonna be a big render hit.

Use skylight instead, just turn up the intensity to compensate for tuning off the illuminator, could also try a skymap image, tinting the objects with some sky color adds realism.

Place a "regular" light in the position of your virtual sun, also use this light for shadow generation, included in GI with one bounce.

if you want to control RT shadow opacity, simply duplicate the "sun light" and turn off shadow casting for that light, turn intensity right down, like 0.2, now you have a "shadow opacity controller"

If i think of any more i'll post back

"We're on an express elevator to hell - Going down"

Old 03 March 2006   #14

Well, while my speakers dry Ill ramble on some more

When you set both boxes in the AA render tab to 255, camera goes in to Averaging mode (camera even says this in it's interface). If I am not mistaken averaging alters the colours of the pixels along object edges, essentially increasing contrast, when you do this in a dark room it is called Mackie lining - something that the 'Un-sharpen mask...' in photoshop tries to emulate. You end up with a sharper image and we use it for still images 75% of the time. If you start to get jaggies (because the image is too sharp) you can either turn sampling up to 2x2 (adding between 10 and 15% to the render time) or turn off averaging by putting a lower number in the top AA box. Hope you haven't fallen asleep yet!

On with the ramble! I work to a scale of 1 scene unit = 1 cm, so 100 scene units = 1m.

On this scale, in EI, I've found the optimum sun distance from a scene is:
On a super bright mid-summer day: 100,000 scene units.
On an dull (or spring/ autumn) day: 32,000 scene units.
At sunrise or sunset: 400 scene units.

If you want to be true to the real world, multiply all those numbers by 100, but sod that, this is CG and EI doesn't do real world falloff calculations.

So, and I'm not necessarily referring to this scene because you have a great look going, if you move your sun (which must be a spotlight) 32,000 scene units from the action, then look through the sun in the world view, then adjust the cone angles of the sun spotlight so it just covers the scene. One last thing to do, divide the sun reference distance (distance from the scene) by 10. That is you light size (3200). Exception: Never go over six thousand in your sun size, the render hit isn't worth it 99% of the time.

Right! So take an object in your scene, those pillars look about 1.75m tall? how many scene units is their Y in the info box... From there you can work out how many scene units there are to a metre et voila, you can get your sun to an optimum position.

Although, like I said, you have a great look, if it isn't broken, don't do what Ian says

Apologies for boring the crap out of you!!!
Old 03 March 2006   #15
This is a great thread.

The EI Manuals should be written this way. Instead of a check list of every toggle and entry box, they should teach what this stuff is for and how to use it.

Excellent info everybody, and Richard -- great image!
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