HELP NEEDED Radiosity Lighting.

[JamesTaylor]

hi all!

 

i'm beginner working on some architectural images using radiosity for the first time and am after some advice on the lighting.

 

The scenes are set up using accurately dimensioned models and incorporate a daylight system with time and location specified. In side the house there are 20 photmetric lights positioned to replicate halogen light fittings, all of which have shadows switched on. However, when i render an image there seems to be an awful lot of light in the spaces (which i'm having to counter act with the brightness and contrast scales in the environment panel) and a distinct lack of shadows which detrats from the visual quality of the piece.

 

I have attached a sample render to illustrate the problems and any advice on the lighting would be welcome particularly on the lack of shadows even tho there switched on.

 

Thanks, James.

[Ricardo Eloy]

Hi, James!

Please, post your settings for radiosity so we can help you, ok?

[]

Rick

[JamesTaylor]

Hi Rick,

 

these are my settings for radiosity, i've included the modifier panel of a sample indoor light, the global render settings and environment menus and the light lister - not sure if the last will be any help

 

since my original post i have made forward movements and have discovered the psuedo colour exposurer. When switched on the viewport image appears very red all over. I understand from the help section this relates to the lighting levels of the particular areas but also realise that it is no subsitute for the eye. I was wondering how much attention to pay to this as a means of setting up radiosity lighting.

 

Also another point i'm not too sure about is the exterior daylight check box under logarithmic exposure controls and wether it should be ticked or not depending upon if the camera is taking an internal or external shot.

 

Thanks, James

[William Alexander]

James,

 

Couple of thoughts,

 

75 refine interations can kill the subtle shadows- samples light in an area and evens it out. Try a lower setting and work up?

 

"Lots-o-lights" There may very well be too many, look into the area lights & possible "web & ies" lighting.

 

Are you using decay-inverse square (piont lights). With out it, the light continues from source with the same intensity vs real world which decays by the inverse square rule moving away from the source.

 

Pseudo lighting is a very valuable tool. It will tell you the amount of light hitting an area. You can be very exact on illuminance and the lighting in the scene. Play with the settings untill you get a gradient of color, to indicate actual and understandable levels in the scene. The "eye" really comes in with the exposure control, think of it as exposure settings for a camera. ie You can get daylight levels on film at night or the opposite

 

The Daylight setting is like putting a 100 speed film in a camera, very good exposure quality in very bright light (daytime), very poor and dark exposure quality inside.

 

Keep pluggin away,

 

WDA

[Fran]

Hi James,

 

Initial quality should be higher - try 90%. Your Interactive Filtering is too high and should be 3 or less or it flattens everything out. For an interior scene, uncheck Exterior Daylight in the exp. control dialog and reduce the brightness. With such a fine mesh on the surfaces, your refine iterations setting should be okay. The high Filtering setting is what is killing your shadows - that and your light settings. As Willilam suggested, either set the decay to inverse square or use photometric lights.

 

Try letting the solution run to completion - 69% with no refines is going to be crappy no matter what, unless you use regathering.

 

I'm too tired to think of much else right now.

[Jaguar lover]

Scale?

Are you modelling in the right scale?

 

You wrote " accurately dimensioned models" -but system scale?...check unit setup..

 

photometric lights and wrong scale = overbright or too dark..

[JamesTaylor]

Hi everyone - thanks for your input!

 

in response to your suggestions:

 

- all my internal lights are photometric spotlights set to halogen and are of the point light type. It was mentioned that there may simply be to many lights present, but i'm working from an architects designs which contain this no. of lights and want to be as accurate as possible, does the no. of lights really matter, surely aslong as there set up correctly it will work correctly?

 

- the quality is set at 80%, the 69% was there because i took screen shots whilst it was computing

 

- i have set the interactive filtering to 1 (much better!)

 

- the unit setup matches the units of the model

 

in relation to the psuedo exposure, altering the min / max display range changes the colour values used for analysis in the viewport but i guess this is only changing the associated scale used for colour breakdown. Also i guess the min / max values relate to the physical scale somehow but was under the impression that the physical scale value was a means of translating standard lights multiplier value into the same values as photometric lights.

 

i'm about to reduce the refine iterations to 50 and re calculate to see what the differnce is. i'll try and get a new image to post showing updated results shortly.

 

Thanks again, James

[JamesTaylor]

this is the newest rendering

 

refine iterations @50

 

meshing size @50mm

 

radiosity quality @80%

 

I have turned off the exterior daylight system to try and see what is happening with the internal lights

 

i have also attached a render with the psuedo exposure on and the second render which was created as a result showing the colour scale, the dispaly type uses a logarithmic scale with the quantity set to illuminance. The min/max values are 0 - 1500lx with the physical scale @ 1500cd

 

the individual light settings are still as shown in my previous post attachment.

 

All Help and suggestions are much appreciated!!

 

Thanks, James.

[William Alexander]

jat,

 

May I suggest, if you are going by what the Architect gave you:

 

Consider using some thing other than a straight photometric piont light, see attachment. A spot in the distribution slot, or web with an ies file based on the specified fixture and wattage, for example.

 

Your psuedo image shows that you have 1500 cd / unit of area Not quite nuclear lighting but awful bright. American light units = foot candles. Sorry it's not international, been working with spheridian measurements and MR, the think box hurts.

 

Normal fc values

10,000 fc -sunlight

1,000 fc -cloudy day

100 fc -office class room

10 fc -dim hallway

1 fc -candle light

 

 

If need be, lower the cd levels ( for the architect,a dimmer switch ) untill the brightest areas are at 30-80 fc, fairly normal bright interior lighting levels. However, the light's distribution as is may not work the way you want.

 

 

 

WDA

[JamesTaylor]

William,

 

your on my christmas card list!!! thats worked a treat......

 

i've been struggling with the light for the past week and was certain it had something to do with the amount of light in the scenes as they always seemed over lit / exposed and very bright.

 

This is my first ever architectural model and pretty much my first time using light and anything but autocad and so its been a step learning curve of guessing what does what. The help i recieved from people like yourself has been brilliant and i certainly wouldn't have got this far without it!

 

linked are a before and after image having used your suggestions, the atmosphere of the after image so much better. The change i made for this render only reduced the psuedo scene to mostly yellow so theres still improvement pending and i'll use web lights as they seem much softer than spots. Hopefully it will remove the harsh line of the light shade from along the wall.

 

Thanks again and i'll post more images as i get the lighting set better.

 

James.

[Fran]

Hi James,

 

While you're at it, reduce the reflectance (not shinyness) values of all of your materials so that they are in the normal range for the material type. Make sure that "Display Reflectance and Transmittance Information" is enabled in the Radiosity tab of the Preferences dialog. The displayed value will turn red if you go out of the normal range when using the Architectural Material templates. There is a brief table of common reflectance values in the Help files somewhere.

 

Everything is neon - what are your brightness and contrast settings in exp. control?

[JamesTaylor]

Hi Fran.

 

When you say reduce the reflectance values of materials i presume that is the reflectance scale setting in the advanced lighting override section of the material editor?

 

I've changed these values so they correspond to those shown in the table of common reflectance values in the help files and switched on the "Display Reflectance and Transmittance Information" in the prefences but i'm not sure about the display changing to red if the value goes outside normal range. When i go to select materials from the scene using the Material/Map Browser the materials have either small red or blue 'balls' beside them. Are these balls what should change colour when the value is within range? because although i've altered the materials i've not seen anything changing colour and am wondering if i've changed the right setting!

 

As for the brightness and contrast values i'm now generally using between 40 and 60 for both inorder to get a decent result. Earlier, before everybody's suggestions, i'd been having to use less than 20 for both (sometimes 0 for brightness). I guess that these values are moving towards a more sensible and maybe expected value as i have been able to refine the lighting setup to a more accurrate setup.

 

The attached sample uses settings of 50 for brightness and 40 for contrast.

 

Thanks for the help, James

[Fran]

Hi James,

 

It would be better to control the reflectance by adjusting the Value of your diffuse colors and by reducing output in the Bitmap Output rollout. When you make adjustments for reflectance, no matter which method you chose, you must re-run your solution to see much improvement.

 

The image is still washed out and flat. Try reducing brightness more. Also, having contrast a little higher than brightness is usually of benefit.

[14343]

Hi Fran!

 

Saw your awsome renderings, just like to ask if you dont mind, do u solely use the max / viz radiosity engine or you are using thrid party rendering software?

 

[Fran]

Hi Myo,

 

Just max 6 or viz 4 radiosity.