Advanced Lighting help!

[fantome07]

I have been trying to get a realistic rendering effect of and interior drawing. Although I have followed step by step tutorials, guidebooks and some tips from this forum, I still can't get it right.

 

This is what I do,

1. I use 18 numbers of free points @1500 cd each with the perimeters as follows- hotspot/beam: 20

Falloff/field : 100

 

2. Logarithmic exposure control- brightness:70

Contrast: 50

 

3. Refine Iterations: 50

 

4.Radiosity Meshing : 500

 

5. Under rendering parameters, i check 'Render Direct Illumination' and check 'Regather Indirect Illumination'. Rays per sample and filter radius i leave them as default.

 

Are the parameters and lighting I have set and used correct? What type of lights do you guys usually use for radiosity? I have tried rendering a few models, but some of them i get it right by chance and luck. While I tried using the same principles on different models, the results differ. Some even look very very flat and some over exposed. Moving or adusting the parameters of the lights would make the whole place darker.And adjusting the exosure will make the interior very flat. Please help...Thanks.

[mwhite]

I'm just starting with interiors and Max, so I'm no expert. But I don't think you want to have a logarithmic exposure for an interior rendering its better suited for an exterior sunlit scene. I don't even use it for exterior scenes since I have found it very hard to control.

 

Good luck,

 

Mike White

[Jason Matthews]

Hello. One thing that you have to remember is that every scene is different. You will have to adjust some of the meshing sizes and refinements. For instance, 500 is not very small. Therefore, every item in your scene is basically getting the same mesh spacing. You can select on items, go to properties, click on the advanced lighting tab, and change the meshing and refinements per item.

 

Did you set the filtering? Usually, set this number to no more than 3. The lower this number, the more refinements you have to do.

 

Next, make sure the anti-aliasing button in the render dialog box is checked. You have a lot of jagged edges.

 

Lastly, I would look at changing the intensity of the lights up higher, and reduce the brightness of the exposure control. Then boost up the contrast a tad.

 

Keep tweaking the settings and work on your materials. The metal on the chairs look too reflective, which brings me to another point. You have to change the material to an advanced lighting overide material and adjust the rflectance scale and color bleed according to the material you are using.

 

Here is the link to reflectance of materials.

 

http://www.cgarchitect.com/vb/showthread.php?t=4046&highlight=reflectance+scale

 

Good luck.

[fantome07]

Hi,

thanks guys for your tips and techniques. I have tried during the weekends and this is the results i have achieved. It is much much better interms of brightness and visibility.However, i still cannot get the realistic feel. Saturn, I have already checked the anti-aliasing, but there is still jagged edges.

 

These are the changes I have made:

 

-I have already increased the individual 'free point' lights from 1500cd each to 6500cd. Is this ok?

 

- Global subdivision setting to 100. plus individual object meshing. for eg., the chairs are now 10.

 

-Filtering is 3

 

-I still use logarithmic exposure control. Mwhite, i tried not to use the exposure control, but everything seems so dark. Is there any thing i need to use in order not to use the exposure control?

 

-brightness is now 60 (down from 70), contrast 50(maintain).

 

-does the chair materila look better now? this is based on the reflectance scale give.(50)

 

 

To make a drawing look realistic, what are the most important factor? what are the numbers u guys usually use for iteration, meshing size, and the type of lighting?

 

thanks once again guys.

[Jason Matthews]

I think it looks a little better. I would reduce the brightness down to like 50 and boost the contrast to like 65. Play with this number.

 

What is the black thing under the glass table? Make sure the object is not excluded from the radiosity process.

 

It has been my experience to not use regathering until the end render. So you may want to try using just the direct illumination option.

 

Next, click your camera and then add a "camera correction" modifier to it. This will straighten up the view a little.

 

There is still this blueish glow coming from the chair legs. It could be the reflection. Try turning off the reflection for the metal of the chair. Render it, and if the blue tint disappears, lower the reflection value in the maps rollout.

 

Also, the pictures on the wall look like they are floating. This could be because the there is no color bleed onto the walls. Keep in mind that the reflectance values and color bleed of materials give the warm feeling you're looking for. If a material is giving off too much color, change the color bleed setting first. Then the reflectance scale.

 

Good luck.

[William Alexander]

-I have already increased the individual 'free point' lights from 1500cd each to 6500cd. Is this ok?

- Global subdivision setting to 100. plus individual object meshing. for eg., the chairs are now 10.

-Filtering is 3

-I still use logarithmic exposure control. Mwhite, i tried not to use the exposure control, but everything seems so dark. Is there any thing i need to use in order not to use the exposure control?

-brightness is now 60 (down from 70), contrast 50(maintain).

-does the chair materila look better now? this is based on the reflectance scale give.(50)

 

 

To make a drawing look realistic, what are the most important factor? what are the numbers u guys usually use for iteration, meshing size, and the type of lighting?

 

thanks once again guys.

 

 

Light intensity in cd is a relative term, so many variables. A good way to check is use the fc at distance parameter. For a mtg room 1500cd should be fine, equaling 35fc @ 2 meters and roughly 55fc at table level. 6500cd puts the floor at 135 and table over 200. This looks like a beakroom it may not need to be lit like office space of 100-300fc at the working surfaces.

 

You have lost much of the contrast by over illumination, imho in the second image. Thats even before adjusting with exposure controls. I try very hard to think of this in photographic terms. The light levels should be real world correct (fc at distance). Then use the exposure controls to capture the "photograph".

 

I doctored up your last image in PS to point out a few things I have found to be helpful.

 

1. The horzontal lines- that appears to be your 100 mesh spacing, see the dark and light areas where the shadow should be regular.

 

2. The circles also reference mesh spacing, not of the chair but rather the recieving mesh of the light and shadow- there is none on the floor caused by the chairs, making them float on the reflections.

 

3. Photoshoped some "GI" or dirt effect in where the floor/clg meets the walls. This really helps tie the corners in.

 

The 3 points above are related through mesh spacing. Big is not good for radiosity, make the surfaces to unifrom. Small makes the solution take waay to long. You need to make the mesh size smaller. This will allow for the GI to show through adjustments in the exposure controls (which ever one you use).

 

One thing that is helpful is understanding that it's adaptive meshing. The global mesh spacing setting only applies to polygons/faces larger than the setting. Changing the meshing for the chair probably didn't do much. Changing the local mesh setting for the floor plane will help, and jack the calc times. You can also control the radiosity mesh properties by subdiving a polygon, the subdivisions are considered in the rad calc. See image- 4mx4m plane with 16 polygons. 2 polygons are severely subdivided first view. The second view is after the rad calc using a mesh space of .5m. The lighting will be much more accurate where the mesh is very fine.

 

Hope it's some help and not too much all at once.

 

WDA