Splotchy light in corners

V-Ray V-Ray Common Gallery
1

What settings can I adjust to get rid of these splotchy lights in the corners?

Not sure if this linked image is going to work…

Thanks,

Gunnar

2

Splotchy light in corners

For some reason I can’t get this URL to referece the image or create A link on this board but here is the address:

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5021391645481756658

3

Splotchy light in corners

it looks like you “Disable BBCode in this post” selected when you posted it. I unchecked that but I still can’t seem to get it to recognize the

4

Splotchy light in corners

About your issue though - are you using our rectangle / omni lights now or are you still using emitters?

5

emitters

I am still using still using the emitters albeit I have turned down the intensity a great deal (I suppose the multiplier represents lumens?).

I haven’t figured out how to get the effect I am looking for with the new lights. the top planes of the pendant fixtures are set at about 1250 and the visable parts of the pendants and the wall sconces are set at 250.

Thanks,

Gunnar

(PS: The BBCode is set to “ON” although HTML is set to “OFF” under the forum options.)

6

Splotchy light in corners

You should replace those emitters with our Rectangle light - the emitters aren’t sampled the same way as regular lights are and I believe that is the root cause of the various issues. The multiplier at this time is just a scalar multiplier - it does not have a physical unit attached to it yet.

I deleted your accidental repost

7

Splotchy light in corners

There are several things that may be causing the light splotches. First of is the geometry of the scene itself. Check those edges and make sure they are touching or joined if possible. If there is a gap or the meshes don’t interest then that can cause the light leaks. You may want to extend the faces so that they intersect just to make sure.

Secondly if you are using Irradiance mapping you can enable Check Sample Visibility. This basically determines whether a sample will contribute to a point’s illumination, or whether it is on the other side of a face.

We had a similar post a little while back. It may also be of some help.

8

thanks

Thanks. I will try both of those suggestions.

I am pretty sure the geometry is tight in this model. It seems strange that those light leaks occur at just about every single inside corner in the model. I know with Viz you could decrease the mesh size and/or check “regather indirect illumination” to solve splotchiness in corners. I didn’t know if Vray had siome setting that would allow for more precision in problem areas like this.

Most of the settings under the options are greek to me. I hope the online manual that you all are working on will explain all these settings in layman’s terms and give examples of what effect they might have on a rendering or why you might want to use them. That would be immensely helpful to a lot of us who have only dabbled in 3-d software before.

I have started replacing the emitters with the Vray rectangular lights and so far so good. However, the fact that these Vray lights won’t render when they are inside a component or a group however is a huge problem, especially for large scenes. Gotta fix that one guys… :slight_smile:

Gunnar

9

Splotchy light in corners

Ok,

I replaced the emitter lights with all new Vray rectangular lights with the same multiplier settings. Here is the image with the original emitter lights:

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5021858907858790402

and here is the image with the emitters replaced by the Beta 3 rectangular lights:

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5021858989463169042

The corner light leaks seem to be better (although they are definitely still there), but its hard to really tell if the rectangular Vray lights make a difference as the image was 800x600 as compared to the original emitter image which was 2048x1536. The geometry is tight. All the reveals in the door surround are made with the push/pull tool in sketchup (as are the coffers in the ceiling where the light leaks are particularly bad).

Here the astonishing part though: the larger image with the emitter lights took 9.5 hours to render. The second one took 3.5 hours just to render an eight of a 800x600 image. That would be 28 hours to render the whole thing. To render the same image at 2048x1536 it would take 6.5 times as long: 182 hours. Same image, same computer, nothing has changed except the type of lights.

Please, please tell me I am doing something wrong.

Gunnar

10

Splotchy light in corners

With the time you’ll have to remember that the 3.5 hrs includes any precalcuations that are needed. From the looks of it your only doing a light cache calculation so I presume your using QMC for primary bounces. I definitely don’t think it should be taking that long though. Your scene isn’t that detailed, so you could switch to IR and see considerable speed increase and not to much of a difference.

A quick note about increasing the resolution of your image. You can actually get away with “lower quality settings” for a higher resolution image. This is because primary bounce engines such as ir and qmc are resolution dependant, meaning that the amount or size of the samples they take are based on the size of a pixel. With larger resolution renderings any given pixel is describing a smaller amount of the scene then at a lower resolution. Depending on how much you increase the resolution, you can make adjustments so that it doesn’t take so many times longer than a lower resolution. I can post more details if people find this important.

Also post some details on your settings so we can see if there’s anything that may becausing it to take so long. It might also be helpful to note subdivisions on glossy materials as that can effect things as well (I see you’ve got glossiess on the floor at least).

11

Re: thanks

Good catch, I hadn’t tried that :sweat_smile:

12

Splotchy light in corners

I let the same image render at 2048 x 1536 over the weekend. 63.5 hours later it is only 5/8 of the way through:

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022882484464773154

If I had let it finish it would have likely taken a little over 100 hours… Yikes. That is well over 10 times as long as the same scene with the emitter lights. Same scene, same resoution, rendered on the same machine. There really isn’t that much difference in the quality of the renderings except the vray lights caused fewer light leaks (although they are still definitely there). I checked the geometry and it is fine.

I am using P4 3.4Ghz machine with 2GB of RAM.

The model is larger than you might imagine. What you are seeing in this rendering is a cross axis of this longer space with multiple light sources:

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022888024972585090

However, the 9.5 hour rendering involving the emitter lights had just as many light sources. I hope there is something I am overlooking because if there really is a 10 fold penalty for using the Vray lights I am inclined to just use the emitters and Photoshop the light leaks.

Gunnar

Here are the settings for the rendering in question (they have been the same for all renderings even the ones that use emitter lights)

Settings Page 1:
http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022884172386920562

Settings Page 2:
http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022882514529544242

Settings Page 3:
http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022882548889282626

Settings Page 4:
http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022882583249021010

Settings Page 5:
http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5022882604723857506

13

Splotchy light in corners

My main suggestion is to switch your primary bounces from QMC to IR. QMC can get great results, but its main issue is time. In my opinion IR can achieve results that are nearly indistinguishable (to the eye) in significantly less time. Unless you have a distinct reason why you’re using QMC, I would switch over. Also I might check what kind of subdivisions you are using on any glossy materials. That might also cause your rendering to slowdown unneccesarily.

Also within your LC settings I would enable Use for Glossy Rays as that will help speed up the rendering. Also if you have a single threaded machine you should change the Number of Passes from 4 to 1 (or 2 if you have 2 threads). This will allow you to skip the step of having to reconstruct those individual passes. Other than that I really can’t say to much without sitting down and looking at it.

14

Splotchy light in corners

Thanks. I will try all of those suggestions when I leave to night to see what kind of speed difference I get.

But I still don’t get why, with all other factors being the same, the v-ray lights caused a 10-fold increase in rendering time over emitting lights. That seems really steep to me.

Gunnar

15

Splotchy light in corners

If you have a lot of rect lights there can be a decent render time increase. Rect lights get sampled much more than simple emissive materials.

I think a 10x render time is a bit much as well, but without seeing your scene I cannot tell you for sure whats happening. Could you upload a copy of this file to ftp://ftp.asgvis.com/incoming ? Let me know the name of it if you do choose to send it to me.

16

Splotchy light in corners

I took all your suggestions Damien and re-rendered. The changes did make for a shortened rendering time (10.5 hours) but as you can see by the linked image, there is still more tweaking that must be done. Even though now there are fewer light leaks in the corners there is a noticable splotchiness to the wall surfaces and a weird “its-made-of-stars” effect going on in the glossy floor reflection.

http://picasaweb.google.com/ggarness/VrayInteriorTests/photo?authkey=UvHXq04EcmY#5023334954974439570

Since I have a Friday deadline for 3 renderings, I will go ahead and render the model with emitters and photoshop the light leaks away. But I would like to figure out what settings will eliminate these problems for future reference.

Thanks,

Gunnar

17

Splotchy light in corners

So I dumped out a debug scene file and it seems there are well over 100 rect lights being created in your scene. That will account for your horrendous render times. Overall your scene is not that complex - < 100k faces, settings are fine. But that rect light issue is a killer. I’m not sure if you explicitly put all these lights in or if there is some error on my scene parsing (I’m leaning toward the latter). I’ll keep you posted…sorry for the inconvenience.

18

Splotchy light in corners

Each face of those wall sconces is a rectangular light and there are 8 per bay plus 8 rectangles on the tops and the bottoms of each of the 7 or so ceiling pendants… so 100 plus lights doesn’t sound unreasonable to me.

There are so many of them because I didn’t know any better way to simulate the effect of diffuse square fixtures. Maybe there is a better way to form the lights in sketch up/vray so there aren’t so many individual faces?

Gunnar

19

Splotchy light in corners

Joe sent me your scene, so I will take a look at it. I’ll see if there’s anything else that pops up as well as try to create that effect with less lights.

20

Splotchy light in corners

Ok - then perhaps you might want to hide portions of the model that aren’t in the rendering. Damien may be able to provide you with more tips. But that many area lights will slow any renderer down to a crawl. I would also avoid using light cache for interior scenes. Maybe IM/QMC would be a better choice for interiors - do you agree Damien?