PDA

View Full Version : Questions regarding luminous polys in Interiors!



prometheus
06-17-2011, 08:12 AM
Hi there!

Im a Newbie on interiors really, Im in a process of populating a gym room with machines, and I have some questions about luminous polys.

In the attached images I have one area light acting as sunlight (credit and thanks to those who posted the interior animated setup on this forum)
I just changed the room a little...and switched to srgb color space.

two luminous simple flat polys as ceiling lights.
The first image has a 100 % luminous setting and 500 diffuse.
the second image has 3000 % luminous setting and 500 diffuse.

Now what value would you recommend for luminous polys?

If I use the higher value, that would also give blotches, so I wonder if it would help or do anything to improve if I should subdivide the polys?

I guess I need to lower the minimum pixel spacing too.

I will encase light polys in to a frame later on, and I believe I should make the polys double sided to get a nice glow spread in to that frame?

Any suggestions?

the color space is set to srgb, see GI settings and color space settings, the test image resolution is 640x480.

I will work on filling the room with more stuff later on.

Michael

dee
06-17-2011, 10:45 AM
Your CS settings are not correct, set it like so:

http://www.newtek.com/forums/attachment.php?attachmentid=95969&stc=1&d=1308328984

You don't need diffuse on the lumi polys, set everything to zero except luminosity.

prometheus
06-17-2011, 11:43 AM
Your CS settings are not correct, set it like so:

http://www.newtek.com/forums/attachment.php?attachmentid=95969&stc=1&d=1308328984

You don't need diffuse on the lumi polys, set everything to zero except luminosity.


Ill go through the CS settings again later..and I guess I knew that diffuse isnīt needed, donīt know where the heck I got that from?

However the question and issue I would like to get a grip on is how much luminosity would be proper to use?
A 100% setting isnīt illuminating walls or even floor enough...but if I were to use a very high luminosity value, the blotchy spots would show up more, so I wonder if it would help to subdivide the luminous poly geometry or if It has absolutly no effect whatsoever to do that?


Michael

dee
06-17-2011, 12:09 PM
Subdividing the poly doesn't have an effect but the CS settings do. ;) Set the luminosity so that it looks good, some scenes need more, some less but min. 100. Also try different positions e.g. placing them in front of the windows.

Builtdown
06-17-2011, 02:05 PM
Why not use area lights on the ceiling and not luminous polys?

prometheus
06-18-2011, 03:44 AM
Subdividing the poly doesn't have an effect but the CS settings do. ;) Set the luminosity so that it looks good, some scenes need more, some less but min. 100. Also try different positions e.g. placing them in front of the windows.




placing poly cards in front of windows?..donīt think thatīs the route to go, area lights perhaps, but luminous polys?



Why not use area lights on the ceiling and not luminous polys?

I might, and thatīs what I initially did, but render times takes a huge hit compared to polys, and Ivé also been recomended to use polys instead.

Im not even sure If I in the end will use this type of long light panels, or simple switch to som round spots, probably also luminous polys.

Michael

Danner
06-18-2011, 05:48 AM
I use luminous polygons all the time instead of area lights, they render MUCH faster and don't suffer from graininess like area lights do. That being said, the effect is not the same, area lights give a nicer oclussion effect. As far as the value.. just go for what looks right, using linear color space you shouldn't have to turn them up over 200% If you still feel they are weak make them larger (unseen by camera of course). I use shadow mapped spot lights a lot too, the shadow can be put on cache and if nothing is moving they are your fastest option.

prometheus
06-18-2011, 06:32 AM
I use luminous polygons all the time instead of area lights, they render MUCH faster and don't suffer from graininess like area lights do. That being said, the effect is not the same, area lights give a nicer oclussion effect. As far as the value.. just go for what looks right, using linear color space you shouldn't have to turn them up over 200% If you still feel they are weak make them larger (unseen by camera of course). I use shadow mapped spot lights a lot too, the shadow can be put on cache and if nothing is moving they are your fastest option.


Thanks for the advice Danner, well I donīt think I can make them larger, and unseen by camera:) they are there to serve as light panels mainly wich are commonly seen on ceilings, not exclusively to light up the room thou it would help realism if they affect ceiling and light up wall and floor a tiny bit...and even the gym machines in the end.

of course I could create two polys, one unseen by camera and larger as you said, and one poly wich serves as the lightpanel onlys perhaps.
Im gonna test with some more objects beneath and encased around the luminous poly as well, to get a nicer spread/glow around it.
Or Iīll go back to area lights if that doesnīt work out.

As mentioned, Ivé got no big issues with the luminous polyīs except for when raising the luminosity values high, the lighting is good except for the blotches that appear from them when increasing it that much, I would like to understand why that is.

Im gonna work on this tommorrow sunday a little bit.

Thanks for the advices everyone, Iīll post some more pics later on, Ivé got a couple of more machines to put in there, some of them heavy on poly acounts, maybe 800 000 per machine X 13 machines perhaps..if lightwave and my machine can handle that along with all vertex normal data from solidworks..puh.

Michael

Danner
06-18-2011, 07:11 AM
You might be able to get rid of the blotchiness if you modify your radiosity settings.

I tend to get good results with
intensity 100
indirect bounces 3
rays per evaluation 600
secondary bounce rays 32
Min pixel spacing 3
Max " " 100

If it gets too slow change to 10 minimum pixel spacing.

Always do a couple of test renders to test "Use behind test" on and off. If you can tell the difference leave it on. if you can't leave it off. On slows renders quite a bit but somethimes it's necesary if you have flat things right on top of other flat things (paintings on walls for example)

prometheus
06-20-2011, 01:18 AM
Your CS settings are not correct, set it like so:

http://www.newtek.com/forums/attachment.php?attachmentid=95969&stc=1&d=1308328984

You don't need diffuse on the lumi polys, set everything to zero except luminosity.


You might be able to get rid of the blotchiness if you modify your radiosity settings.

I tend to get good results with
intensity 100
indirect bounces 3
rays per evaluation 600
secondary bounce rays 32
Min pixel spacing 3
Max " " 100

If it gets too slow change to 10 minimum pixel spacing.

Always do a couple of test renders to test "Use behind test" on and off. If you can tell the difference leave it on. if you can't leave it off. On slows renders quite a bit but somethimes it's necesary if you have flat things right on top of other flat things (paintings on walls for example)


Dee..hereīs the difference between my "wrong" CS settings, and how it looks with your recomended CS settings...see Images.

Danner...Im not sure your suggested settings would work better, My settings for the images above seems to be more enhanced...see GI & Camera settings.

I have higher settings in inderect bounces rays per evaluation and secondary bounce rays, Minimum pixel spacing set to 0.5 (yours 3) and
a very high Maximum Pixel spacing at 600.

now these test renders most likely have a too low AA setting in order to get decent final results.

I donīt think Itīs the adaptive setting that causes the splotches..since Itīs not really a grain issue more of a splotch issue.
Taking a look at the trouble shooting guide at the Except radiosity guide..http://www.except.nl/lightwave/RadiosityGuide95/index.htm

It might be that I should lower the maximum pixel values here?

Regarding the results of the different color space settings, Im not pleased with any of them..the first with my "wrong" settings are to washed out..and the other one is to dark and saturated.

Michael

prometheus
06-20-2011, 04:20 AM
Some different tests with luminous polys, and notes!

I guess that double sided polys isnīt what we need or want in these cases, but interesting to see how it affects the scene, especially when you enable doublesided and also have a very high diffusive amount wich affects the walls differently as opposed to only luminosity...see images.

Havent made the light panels complete either, they need a frame encasement.

Michael

Danner
06-20-2011, 07:23 AM
... My bad I hadn't noticed you posted your render settings.

Diffuse will make your panels brighter, thus affecting everything around them. The difference from luminosity is that going to high values on difusse multyplies what ever light is received by the diffuse value. Luminosity is uniform.

I'm really curious about those black artifacts, I don't recall getting them, but I don't usually go as high on the luminosity. It almosts looks like you have glow or corona or similar since the luminous pannel invades the the fan blades. As far as the colorspace I would stick with what you had initially, then do final color correction in a compositing app.

prometheus
06-20-2011, 08:42 AM
... My bad I hadn't noticed you posted your render settings.

Diffuse will make your panels brighter, thus affecting everything around them. The difference from luminosity is that going to high values on difusse multyplies what ever light is received by the diffuse value. Luminosity is uniform.

I'm really curious about those black artifacts, I don't recall getting them, but I don't usually go as high on the luminosity. It almosts looks like you have glow or corona or similar since the luminous pannel invades the the fan blades. As far as the colorspace I would stick with what you had initially, then do final color correction in a compositing app.

Uhm..I actually added some glow in the image processing, but Im not sure if that is the cause of the black artifacts, have to check later on to find out what it is and to understand it.

I do have some concerns on how this would look on a printed broschure, I printed out a sheet on our canon pixma pro 9000, and it didnīt match the colors on the screen exactly, It is pulling toward magenta bleeding..(as many prints might do I suspect)

My dell monitor U2410 (wich I love) is setup with a preset mode for Adobe Rgb, Perhaps I should have worked with the Srgb mode preset wich are available in dell monitor presets?

These colorspace settings and calibration and color profiles are a mystery science, I need a proper course somewhere:confused:

Michael

prometheus
06-21-2011, 05:52 AM
Tracking down the black artifacts on the luminous polys..

I had the image processing on with limit dynamic range, turning that off will get rid of the black artifacts, however the limit dynamic range are there to improve the AA on very bright areas, and as you can see in the attached image, without limit dynamic range you get much more jaggies.

I will try and see if I just can correct some of the values in the limit dynamic range, or simply just turn down the lumunosity from that extrem value of 3000%.

Michael

ingo
06-22-2011, 01:56 AM
Hi Michael,

the blotches are there because you dont have enough "real" light inside, only bounce light. You can either give the sbr a higher number or add some real light. An easy solution would be a distant light behind the camera, with low intensity and shadows turned off.

And dont forget post production. Just look at Jasons nice interiors, he renders a pretty dark picture out and he than uses Photomatix to make them look brighter.

prometheus
06-22-2011, 02:32 AM
Hi Michael,

the blotches are there because you dont have enough "real" light inside, only bounce light. You can either give the sbr a higher number or add some real light. An easy solution would be a distant light behind the camera, with low intensity and shadows turned off.

And dont forget post production. Just look at Jasons nice interiors, he renders a pretty dark picture out and he than uses Photomatix to make them look brighter.

uhmm...what blotches do you mean? room blothces?

Right now Im having issues with the black artifacts within the luminous polys right now.

I think Im getting rid of the overall blotches almost in my current scene setup, some changes in the GI settings etc, but I donīt think it was a question of lacking of interior lights, the room looked decent when I first tried it with a standard value of 100% of luminosity on the poly panels, but once I increased to 3000 % the bouncing becomes very appearent and I believe that can only be fixed with increasement in AA and in the GI settings with increased bounce rays and some other settings there.

The room is the animated sunlight/suncolor setup scene wich was posted somewhere here in the forums, I just changed the room a little.
Im my current scene setup, Im also putting an area light in front of the camera to simulate a slight flashlight, wich also will help to highlight specs on the machines.

The black artifacts on the luminous polys, can be reduced or removed, if I choose to not use dynamic range limit, but this also has to do with me using the perspective cam wich has a different AA method, If I were to use classic cam I wouldnīt get this artifacts and I would also get a much nicer AA on the edges of the luminous polys....so why donīt I use that instead??

well I must use the perspective camera in order to retain proper vertex normal smoothing on the imported cad machines, classic camera renders those incorrect unfortunatly.

Thanks for the advices..Ill check in to those tips anyway.

Edit ..even if I use this animated sun setup, Im not doing an animation sequence for this right now, I just wanted the setup in order to change sunlight realisticly in the room.
in the end Im gonna print a broschure of some gym interiors.

Michael

ingo
06-22-2011, 05:19 AM
are the black artefacts on the luminous polys or on the geometry of the light behind ? Usually when my renders get those artefacts its related to specular of the object, when i switch specular off its gone.

prometheus
06-22-2011, 06:16 AM
are the black artefacts on the luminous polys or on the geometry of the light behind ? Usually when my renders get those artefacts its related to specular of the object, when i switch specular off its gone.

Thereīs only the luminous polys consisting of a flat poly, close to the ceiling
and thereīs only luminosity on the lum polyīs all other settings are off.

as mentioned those black artifacts are most likely some sort of AA issue, as mentioned classic cam doesnīt get these artifacts, but perspective cam does and the same goes that having dynamic limit range on in the image processing, set them to off will get rid of those artifacts also, but will leave more nasty jaggies around the lum polys.

Try some luminous polys close to a ceiling, set a very high luminosity on them, and render them with dynamic limit range on and a perspective camera..then render them with classic camera and youīll see the difference.

Michael