Has anyone done any side by sides? I'd be interested because currently I dont use GI or GR and am wondering if I'll get much of a realism quality boost if I do. Basically, I'm the cg guy at a visualization company and we do viz for proposed buildings and the such. I'm trying to get the most realism I can because I have to compete with the likes of VIZ and 3DSMax on a regular basis. My work has to stand up with the likes of them. Has anyone done a side by side or has experience with this?

Well, one thing I have noticed is that, when you load up a preset atmosphere that is NOT GI or GR, and then go into the lighting settings tab in tha atno editor and make it GI or GR, the light gets darker and "fuller"... it's kind of hard to explain, but the shadows get darker, and the light gets not brighter, but changes color a bit and creates sharper contrasts. Hope this helps. -Zak

OK, I'll tell you that I always use GI for outdoor scenes. GI spreads shadows in a far more realistic way than standard lighting, especially on plants. Try it on a simple scene with a few trees, you'll see. Choose any atmo, and check GI, you'll see your scene gets darker as Zak said, because it's like I said GI spreads shadows. You'll need to raise the skydome lighting gain ( at least 60%) so your scene gets brighter. The shadows will also take a nice bluish color if you use a sunny atmo, just like in the real world. Then I usually set the sun's shadow to 80% only, so the scene is less dark. (100% shadows is not real world accurate anyway, because the colour black is used in Vue for shadows, and it's not the case in outdoor lighting.) Tip: move the GI quality slider to -1, speeds up render times without affecting quality. GR is different, and is better used for indoor scenes. GR simulates how the indirect lighting coming from light sources bounces from the objects touched by the light rays. Objects hit by light will absorb some of the light, but not all of the light ( depending on the optical properties of your object's materials), so the remaining light bounces off the surface of your object, and reaches the surrounding objects. And so on. This is the most accurate method for photorealsim in CG, and I think Vues engine, although really slow is very good at GR.

-Really good advice...!

Thanks Bruno. I'm going to do an official test soon here on an actual render. Thanks! -Ryan

well GI and GR improve realism dramatically ! standard ligth make flat image, without "rebound" of light around the scene. GI make a most "volume" on shadows and on light GR is the best ! also colors in rebound-lights... but GR vue engine is terrible slow !!!

Cool... how long (if you remember) did each take?

Attached Link: Vicolo with GR

a simply sphere is an "istant" render... different if you use complex objects... i can tell you one example : my image Vicolo use GR was about 20h, about 2h in standard light, not try in GI...

Wow. I dig the realism. However, 20 hrs? I usually render at 3000-3600. It'd simply take too long :( Whats your workflow for GR? Do you set all materials at a set reflectivity and just work through them...adding specularity/reflections as you go?

Ryanspaulding, If you have rendercow on other computers you can network them all together via an ethernet cable and get them all working on your pic. You're supposed to be able to batch them too so you could leave them all going whilst you are away or something. I have 4 puters linked for rendercow, 2 macs and 2 PCs Love esther

For outdoor scenes I always use GI, but I tone down the quality to -1.0 or -1.5. This will reduce your rendering time down and you will barely notice the difference on outdoor scenes. The example is a crop of an area from my latest visualization, the bridge face is from the existing photo but the columns, wall, road, barriers and cars are Vue rendered. Notice the subtle shading on the wall as it gets darker the farther under the bridge it gets. This is the affect GI has on a model. I will post an example of a direct comparison on a building shortly.

Standard Lighting on a condo

Now with GI I had to adjust the standard lighting when switching back and forth in order to attempt to get as close as I could to the look of the GI render, the most noticeable differences are in the shadows, like it was said earlier, a LOT less flat.

Oh, I might also add, don't bother with GR on an outdoor scene, unless you're really really looking at it you won't notice the difference between GR and GI on the large outdoor scenes and the difference in render time is insane.

Attached Link: http://www.art-head-start.com/

Here are some Vue 5i renders from my upcoming eBook for digital art students at art-head-start.com.

The setup in Vue:

No GI, no Radiosity, just ray-tracing:

With GI:

With GI and Radiosity:

Beautiful work nanotyrannus!
Right, the effect of Radiosity render is usually not very visible in distant outdoor scenes, so it's not worth all the extra render time.

HTH :)

Message edited on: 11/10/2005 18:50

Here's my test. Both rendered at 3000 px wide. No GI took 9 hrs. GI took 23.

I must say, I'm disappointed with the speed for quality tradeoff. I'm not sure the GI version looks any bit better.

You know, I actually think that RyanSpaulding's standard Ray-Traced image is better than the GI one... maybe it's just me... -Zak

I think RyanSpaulding's GI render needs more ambient light to get the effect of GI. Turn down the ambient light slider in the lighting tab to at least 25% (e.g. 75% ambient).

I'll try dburdick's suggestion tonight. It may be my file setup.

You might check your rendering settings too, I almost never use anything higher than the "superior" setting and usually have my user settings if needed at a little bit higher, I never use ultra.

Default user settings are a good trade off.

Actually, we should have a thread about this...about what to look for in GI/GR to make a better image. If I would have known ahead of time that you have to have ambient light set at a certain level, I coulda changed it. Other than ambient light, and other changes perhaps?

Here are my lighting settings. My rendering was Superior before I made some changes in User Mode. It's not what Ultra is.

Hmm. You might do a test using Global Ambiance (the middle ground between GI and Standard) and see if that gives you a happy median between the flat standard lighting and the time intensive GI. Here's a screenshot of the lighting settings I had for the condo building GI I posted earlier. I'm running time tests now to see what the time differences are.

Attached Link: http://www.informatix.co.uk/piranesi/index.shtml

BTW- something that doesn't get much mention- Reworking your render through Photoshop. I have found that a TREMENDOUS difference can be made on an image- saving MANY hours of rendering time, by using Photoshop to tweak everything. People don't talk about this in the Photoshop Forum- or here...

That's why V5I has all of those render output options that can be saved as PSD files with layers and tweaked!

I've been also working to get Informatix and E-On together so that V5I will output EPIX files. I have been told by E-On that it can already be done via Python- but of course they don't offer a Python script (heh!) But Informatix is pushing for it also with E-On- so hopefully it will happen someday and we can use V5I with Piranesi (see link)...

I don't think it's useful to give more than generic settings and general tips for high quality renders. Every scene is unique. If you want to bring out the best in your scene, you should let it tell you how it wants to be rendered - by looking at your scene very carefully and by trying many (small area) experimental renders. And several small and barely noticeable tweaks can add up to a significant improvement. Applying someone else's "render formula" won't give you the best result, nor teach you as much, as lots of experimenting. Of course commercial workers have to meet deadlines, but they should still do at least one intensive and perfectionistic experimental render for learning purposes, IMO.

RyanSpaulding: As I suspected you need to use more ambient light in your atmosphere settings to see the effects of GI. Move the the light balance slider towards "Ambient" - try it at 25%.

Message edited on: 11/12/2005 02:33

Very nice thread. Nnanotyrannus, Ryanspaulding, may I ask you where do you model your buildings?

In my opinion, much more important than the GI-GR dilemma, is to use an image-based lighting scheme. And mind, it does not necessarily have to be an HDRI to produce good results. If the photograph is good and properly made, even a normal photograph can produce very good results. Attached is a test scene I made using a photograph of mine. What you see is an "environment" (i.e. IBL) scene that uses my photo as source and the DEFAULT values (yes, default! No need to tweak sky illumination). GR is used but I tested GI and it gave a practically identical results. Both GI and GR were very fast with this scene. Rener mode is Superior. Orio

Orio- My models were built in Autocad using plans from the architect and then imported into Vue. I'd have to second jc's advice as well, experimenting really is the best way and he's right, every scene is definately unique, depending on a lot of variables in the scene. But he's also brought up a good point that you and I are both very familiar with. Commercial work (or in this case architectural/visualization work) is very short on time, most of the time you're hanging on just trying to scramble to meet the deadline and you're usually pushing right till the last minute with stuff, so experimenting is not always possible, which is too bad because I'd love to go back and tweak some of my previous sims just because I know they could have turned out much better if I'd just had an extra day budgeted. Orio, I'll have to do some experimenting and see how IBL comes out on the model I've been testing with, thanks for the suggestion.

Attached Link: http://www.renderosity.com/messages.ez?Form.ShowMessage=1961255&Form.sess_id=376235&Form.sess_key=1

Here's an image of the RDNA Roman Villa made with the HDRI file that comes with Vue 5. I did this render over a year ago when Vue 5 first came out.

Personally- I think HDRI renders FASTER and often looks BETTER than most other choices. I didn't use any extra lights or atmosphere in this scene- but HDRI-IBL gives you the options of using FILL and KEY lights- as well as mixing in a Vue Atmosphere. Plus of course- you could use Shadow Maps and Reflection Maps with the Key and Fills- so LOTS of choices...