View Full Version : Grainy transparency problem!

12-08-2005, 03:55 PM
Hi guys!

Please take a look at the rendering from a straight forward door with straight forward windows in it. Why are windows so grainy!

I'm using fresnel reflections with radiosity and an HDRI image. Here's what I have tried. I blurred the HDRI image, I cranked the Rays per Evaluation all the way up to 16x48, I adjusted the Ray Recursion Limit and IM GETTING UPSET WITH LIGHTWAVE!

Excuse the screaming, but everytime I solve one problem with LW, another stupid thing happens. Anycase, I needed to vent a bit!

Can anyone pleeez help?

12-08-2005, 04:12 PM

...maybe check if you have double-sided polygon ( polygons over polygons)

do this step:


it may resolve the problem.

if not delete all your glass and replace by a big box with a bit of volume ( not a flat polygon)

Hope it works .

Do you blur the HDRI with a lightwave image filter ?
if you do it with HDRshop or an external program, it's not working inside LW.
Must be blurred in LW ( to save rendering time use a small HDRI ( ie: 300*200)).

cheers !

12-08-2005, 04:15 PM
I've checked the polygons, there are no duplicates. I'll try blurring with an external application!


Captain Obvious
12-08-2005, 05:38 PM
Are you using blurred refractions, or a bump map? If so, you'll have to turn up the anti-aliasing to get rid of the grain. If you're using shading noise reduction, turn that off and increase the anti-aliasing. Shading noise reduction is only applied to things NOT seen through transparency or reflections.

12-08-2005, 11:06 PM
You can try:
1) do not use raytrace transparency
2) switch off shading noise reduction
3) do not use adaptive sampling

Captain Obvious
12-09-2005, 01:41 AM
You can try:
3) do not use adaptive sampling
Or at least lower the threshold.

12-09-2005, 04:06 AM
sorry , you didn't understand be well.

Don't blur it in an external application : it will make no difference in LW ... :thumbsdow
you must blur the HDRI pic in LW with image filter ... :thumbsdow

To finish, try to use a JPG or tga as environement map ( not a real HDRI) and see if it makes a diference.


yes I know it sucks ... got similar problems..

note: a dirty trick ! is to use a noise reducer plugin ( photoshop tool) , grain killer ...

12-09-2005, 10:11 AM
would it be possible for you to post your scene? with the HDRI in question or a link to it/path if it is in LW content.

It'd be interesting to have a go at this.

12-09-2005, 10:26 AM
Thanks for offering habanero, and thanks for all the advice guys!

I turned off the shading noise reduction, upped the samples per evaluation on the radiosity settings, and it seems to have fixed the problem!

I'm rendering a pic at the moment, I'll post it when it's done!

12-09-2005, 10:49 AM
So here's a quick render, about 8 minutes. It is a bit grainy overall, but this will vanish as the samples per evaluation are increased.

12-09-2005, 11:48 AM
Here I upped the rays/evaluation setting a bit here. I've now added a bit of a bump to the windows.

Captain Obvious
12-10-2005, 06:33 AM
That looks better. It doesn't look as grain on the windows, in my opinion. It looks like a very small low-frequency turbulence bump map. :p

12-10-2005, 06:42 AM
Thanks Cap!

I've added a bump map to the windows, but the first pic in this thread was without the bump. I first wanted to get the rendering right/better.

Personally I don't very much like LW's renderer, and frankly, I'm growing less and less fond of LW. But well, since I've brought the software, I'm stuck with it as I'm strapped for cash right now.

Some days I think I should have saved a couple of bucks more to buy Studio Max or Cinema 4D.

12-10-2005, 08:35 AM
I guess it doesn't like you either ...

Captain Obvious
12-10-2005, 11:30 AM
I think you're lacking patience, Josamoto. You can't just hit "render frame" in Cinema 4D and expect good quality, especially not when using radiosity. If you have problems, just ask us and we'll help you. Don't assume you have problems because Lightwave is bad software.

12-10-2005, 03:24 PM
Yep! I agree. I am a very impatient person. I'm the type that sometimes start panicking when deadlines approach too fast and the job is creeping too slowly.

One thing that concerns me now, is that I'm starting an arch.viz company in South Africa next year. I can't afford a render farm, and making super realistic renderings cost a lot of time.

To get slightly back to the subject of this thread, it takes me about 40 minutes to render this door in LW. So what am I going to do if a client expects me to render an entire house, with a basic garden...as an animation of 60 seconds long!!!

Anyways, I'll be starting a new thread on that later.

12-10-2005, 05:08 PM
If you are going to start an ArchViz company, I'd recommend Fprime. The render below is rather realistic glass with full internal reflection and 3 ray montecarlo render, 5 mins total to model/set up and another 6 for the render. Never mind the modelling and materials, The glass there is about as slow rendered and noise loving glass you can get:


For what you are talking about, using motecarlo radiosity is hardly common, you can get great results in seconds with occlusion or some of the tricks mentioned here (http://forums.cgsociety.org/showthread.php?t=300214). Vray is also something you maybe would want to check out.

I think to that it frankly speaking is your skills that is lacking in this case, there are lots of peope using LW for Arch Viz and at certain things speed is actually an major advantage of LW. If you can't afford a render farm, it is very possible to render on the net, even this is far cheaper for LW than for some other programs. And Fprime will allow you to just render till deadline and leave it at what is, it has a different kind of workflow than most other renderers out there.

Edit: I didn't notice the Word HDRI first. There are separate issues with them, search for HDRI and noise and you will get input. Fprime though is very capable:


This is like a 10 min render, not that it would be impossible to make that a little bit shorter.

12-10-2005, 07:04 PM
Thanks habanero!

Were all still learning, and I agree on the skills level. We'll I'm not a complete beginner I would say, but I'm definitely not the best either. Slowly but surely, I'll get there! We are all learning hey! :)

Nice door, looks almost as good as mine...just mucking about with you there! ;)

I think I'm going to have to learn to fake a lot of things to get better results.

Just a quick one on VRay, does it actually support LW?

12-10-2005, 07:07 PM
...I think you meant KRay Habanero. Thanks anyways, you got me pointed in the right direction!

12-10-2005, 07:09 PM
Oh, and by the way, I tried the Kray beta evaulation the other day. I tried it with a simple scene which contains a floor and a floating sphere. Everytime LW renders (using Kray), it simply crashes.

I probably need to do something special to my scene to get kray working. I'll check out a few tutorials.

12-10-2005, 08:02 PM
Sure did mean Kray ... I seriously need to get myself more sleep these days ... I don't know anything about it but that it can give really impressing results/time, particularly for static scenes with camera fly-throughs like you mentioned.

If you have photoshop the Photoshop PSD export [image filter] can be an incredible time saver as well, you can do stuff like picking each surface, blurring while keeping reflections sharp etc. as well as mixing render results, putting the problem items in a separate pass with higher setting. It is considered a little unholy in the LW forums, but to quote a Norwegian philosopher called Hank von Helvete: Sell your body to the night!

I only bougth LW this summer myself, still learning to say the least :]

12-11-2005, 04:59 AM
Where can I get the PSD export filter. That will be very helpful!

I downloaded kray again last night and finally got it working. Will be playing around with it later on, and if its good, I might even buy it...if I can scrape the cash together for it.

12-11-2005, 08:01 AM
Already in there! ctrl+F5 -> processing -> image filter -> psd export and there are lots of options!