Splotchy and dark... what is the general cause?

[devres]

Not sure what went wrong here. Any ideas how to make this smoother and less blotchy? ESPECIALLY the molding... eesh!

 

I used IR map for primary and qmc for secondary.

 

Thanks for any help.

[blade911]

hey thr

 

try usin light cache as secondary and u might wanna use exponential as the color mapping. blotches are common when usin qmc n linear multiply, at least to my experience

 

increase the irr settings a bit too

 

also ther seems to be lots of artificial light inside ur room? gives it a sky light effect. jus keep one target light outside as ur sun or vray sun.

 

chek it out

 

cheers

[abl_langs]

did u modeled it CAD? co'z for me that seems to be the problem..

[Brian Smith]

yes...switching to light cache should fix the problem. You can fix the problem while keeping QMC but the settings in the QMC Sampler rollout will have to be increased so much that it won't be worth the rendering time.

[devres]

I modeled in Arch Desktop... is that problematic?

 

Light Cache... ok, I've had fantastic results with light cache for single images, but for the flythroughs I've never been able to get good results.

 

Currently I render between every 50th and 100th frame multiframe incrmental with the IR map. I tried the same with light cache but it just didn't work very well. What is the trick with that? More samples or what?

 

I remember watching the gnomon dvd said something about the number of samples being distributed thoughout the range of frames.

If that was the case, would say 5000 samples for Light Cache on a 500 frame animation be a good starting point for a high quality render. (once again, doing every 100th frame for the map calculations)

[Brian Smith]

Light cache needs to calculated in Fly-through mode...not Single Frame...and it only needs to be calculated in one frame (which frame doesnt matter). Good test render values are 100-250...good production render values are 10x the amount, 1000-2500.

[devres]

So, on a 500 frame flythough.

 

I would end up with Primary of IR - secondary of LC

 

Now, for IR I have to run my multiframe incrmental at every 50th to 100th frame.

 

So you are saying for LC I set it to flythough and only calc one frame? What happens when/if I turn a corner or turn around? I'm slightly confused here.

Sounds too good to be true.

 

Thanks for your help!

[Brian Smith]

When you turn the corner everything will look fine because LC is created globally in fly-through mode. The Nth frame setting is highly dependent on how quickly your view changes so every 50th maybe ok, but it might be too infrequent if you're camera moves quickly. If your view changes abruptly, you might need to set it at every 10th or 20th.

[devres]

Brian.. thanks for the help man.

 

I still have a few questions though.

 

So our shots are always slow moving interior shots, with an exterior here and there. I understand that the speed has everything to do with the nth frame setting. I have no real problems with the IR workflow.

 

I'm still a bit confused as to how I would set my render settings for LC. Will I be running the IR calc and the LC calc at the same time.

 

Set IR as I normally do, then set LC to flythough and just run it at my normal nth frame setting. Or do I save the LC on a second calc alltogether only doing one frame?

 

I'm excited to give this a try. Thanks again for your time and your help.

[pg1]

Set both primary and secondary engine to light cache

 

set the light cache to world (for animation) and fly through mode set the light map to be saved somewhere u can find it.

 

The light cache is now worked out for one frame but shoots rays throughout the whole animation timeline (not the amount of keyframes so go to the time configuration panel and make the total frame no. the same as the length of the animation)

 

Hit render

 

Now you have you light cache calculated and saved go to the light cache panel and change from fly-through to from file and find your saved light map.

 

Change primary to irmap and leave secondary to light cache. The irmap is calculated faster as it can read the info. in the light cache

 

Calculate Irmap and save it out.

 

Finally primary to irmap (which now has the info from the light cache and its own irradiance info) and secondary to none.

 

Turn on render final image in global switches and render.

 

If you haven't seen it already check out

 

http://www.spot3d.com/vray/help/150R1/tutorials_imap2.htmhrough.

[Brian Smith]

Here is a quick guide I wrote for a class. Should help.

[devres]

You guys RULE!

 

thanks again... I'll post back with updated results next week some time.

[martin walker]

Brian,,,thanks for posting that PDF...but isnt calculating the Irradiance Map first, then the Light Cache pointless ? If Im not mistaken, the Light Cache is a rough approximation of the GI and the the Irradiance Map uses the LC data and refines it in a secondary pass ?

 

interested to hear other peoples takes on this....especially Chris Nichols if hes reading this !!!!

[Brian Smith]

Martin,

I am leaving with the family at 3am tomorrow morning and driving 1200 miles from tampa to dallas for turkey day so i will have to make this short for now. To answer your question...yes and no. Yes the Light Cache is a rough approximation of the GI but the results either way are going to be very similar, both in time and quality. I should have made mention before but this is not THE way to do it, but a way. It was a quick document created in a class a while back. It was done before a lunch break when we had a small window to get a good IR map calculated. It was actually dictated by our timeline for the class...we were taking advantage of our lunch window and trying to get a decent IR map calculated (which takes much longer than a good LC). I didnt even recall the way it was written...i just posted. Bottom line, no method or group of settings is going to be the only or best way. If a scene were structured just so, you could get away with a LC for 1st and 2nd and the results might be decent and the GI calc. cut in half. In other scenes, your LC settings would have to be too high (to achieve the same quality as an IR) to warrant using LC for both. I will often render a IR map first if I know that it's going to take 6-10 hours and my LC only takes 1 because i want to take advantage of the 6-10 hours i have off at night, come in calc a quick LC, and send the animation to net. render. It's that sort of thing that manuals neglect to talk about. A lot of manuals teach programs well but not necessarily practical application.

[Christopher Nichols]

You need to calculate the LC first. The Irradiance map depends on the Light Cache. Basically you need to think in of the rays in reverse. First the secondary bounces, then the primary bounces, then the camera.

 

Vlado wrote a basic outline tutorial on the subject:

http://www.spot3d.com/vray/help/150R1/tutorials_imap2.htm

 

BTW... if you want more detail in that molding, try using the detail enhancer in the new vray 1.5. It is designed for that.

[devres]

First off I would love to show my gratitude by sending out some small holiday gifts to those of you that helped me out here. (Trust me our office gives nice gifts)

 

So...

 

Brian

Christopher

Martin

 

If you can PM me an address I'll shoot some stuff your way!

My way of saying thanks and hoping that you'll be there to help in the future.

 

Thanks again you guys. I'm experimenting right now and am already getting some much better results.

 

In regards to Vray 1.5 we are having major issues over here with stability. I think we need to go back and uninstall all the old stuff and start fresh because I can't get any of our heavy scenes to run without crashing. It works perfectly on smaller scenes which really kind of has me stumped.

 

As of right now lol.. as I think about it we have too much stuff installed, multiple versions of Max, Vray, RPC, VR4Max, on and on. It's time to refine the workflow. I think I may stick with 8 and 1.47.03 until the first SP for Max is available (and hopefully an update to Vray as well).

 

Thanks again to everyone.

[pg1]

Thanks for clearing that up Chris/Martin

had my brain in a knot trying to figure out how you could work the light cache after the irmap