problem interior scene in mr

[alejandroserranomonforte]

hi how are you,

first i want to say sorry because of my english

 

well, this is my problem.

 

i am starting in 3ds, and too im starting learning to use mental ray.

i have been trying to make a interior scene but i have many doubts about it. im using only a daylight system and a mr sky portal lighting. Final gather with 1 bounce, a mr photographic exposure control and a&d materials (with ao and round corners).

 

first, Do i need to use gi? thats becouse i find in most of the cases people use it,. Second, i dont know in which point of my work something like white circles appear in all the scene. ive tried to increase fg and image precision, decrease and increase bounces, and nothing. please help meee

 

 

sorry for my ignorance

thanks

[alejandroserranomonforte]

well i decreased fg bounces to 0.

i got this:

 

 

 

 

anyways it still with this white spots

[SandmanNinja]

Welcome to the forum.

 

Looks like moisture on the camera lens.

 

Firstly, always drag a basic gray material onto the objects in your scene.

The colour the objects have on them do not have the right 'properties' to accurately reflect light.

 

You can use photons, but you don't HAVE to use them. I find they are more accurate and can produce renders quicker.

 

You may not need a sky portal - turn it off. Leave it there (but turned off) for now. As you add things to the scene, you may need to turn it back on to bounce some light around the room.

 

Here is what I do (basically) to get my photon solution 'right':

01) add mrSun, mrSky & mrSkyPortal to the scene

02) NO Final Gather

03) Global Illumination - Max # of samples: 2, Max Sampling Radius: 10mm

This will give us where the photons are hitting

04) Increase Max # of samples to 100 & Max Sampling Radius to 100mm

This should start producing soft, flower-like blooms of light on the walls

05) Increase the radius to 200mm and the soft blooms turn into overlapping, general light

06) Increase the radius to 300mm and the overlap almost turns into a single uniform layer of light

 

At this point, you can see where you have 'weak' or dark areas with no photons. Keep in mind that rooms will naturally have darker areas. Ying/Yang - Shadows balance out Light. One enhances the other.

 

Turn on Final Gather (with 0 bounces - you don't need bounces with Photons) and you should get a nice light solution. Don't forget to untick the [ ] Max Sampling Size - I find it works best if we let 3ds determine the max sampling size. It's good for getting the scene right, but can cause grief down the road.

 

Hope this helps.

[alejandroserranomonforte]

thanks joel

 

do i have to put a logaritmic exposure?

thanks again

[alejandroserranomonforte]

well i put a mr photographic Exposure Control, with a value of 12.

i got this:

 

 

i did something wrong?

it is better but its still like spotted

 

ill try with other materials maybe its the problem

[SandmanNinja]

Hi

 

Being a photographer, I now only use mrPhotographic with 'realistic' camera settings for the f/stop and film speed (ISO). So for interiors, I'd use 1/4, 1/8, 1/15 and even tho I'd use ISO400 normally for interiors, it's too grainy so I use ISO100.

 

You can't begin the light solution until you have a more standard material on there. The 'materials' that are on the primitives by default do not reflect as the other materials do.

[alejandroserranomonforte]

so i must not use a&d materials in the scene?

then which material can i use for walls?

 

thanks

Edited July 11, 2009 by alejandroserranomonforte

[SandmanNinja]

Oh, I wasn't saying that. I just meant to start with, to use a basic gray material. Just something other than NO material, because the 'colour' that comes standard on those primitives will not react with light properly.

 

I find lighting a 2-step process:

First get the lighting near enough to start working on the guts of the scene

Then once the scene is populated with furniture and has material/textures on the various objects in your scene, you'll find you'll usually need to tweak your lighting a bit.

 

Check out the iPlan on my website (the link is in my signature). That shows how big a difference just changing one aspect of the scene - the texture on the floor changes from render to render. Look at the reflected light as the floor texture changes. The biggest surfaces in your scenes will be the walls, floor and ceiling.

[SandmanNinja]

Check your email - just sent you some files.

[alejandroserranomonforte]

oh man your renders are awesome

check your mail ive sent the file

 

thanks

[alejandroserranomonforte]

and joel

 

in the email you said Max Sampling Radius: 100cm

it wasnt mm?

 

thanks

[RevitGary]

 

Here is what I do (basically) to get my photon solution 'right':

01) add mrSun, mrSky & mrSkyPortal to the scene

02) NO Final Gather

03) Global Illumination - Max # of samples: 2, Max Sampling Radius: 10mm

This will give us where the photons are hitting

04) Increase Max # of samples to 100 & Max Sampling Radius to 100mm

This should start producing soft, flower-like blooms of light on the walls

05) Increase the radius to 200mm and the soft blooms turn into overlapping, general light

06) Increase the radius to 300mm and the overlap almost turns into a single uniform layer of light

 

At this point, you can see where you have 'weak' or dark areas with no photons. Keep in mind that rooms will naturally have darker areas. Ying/Yang - Shadows balance out Light. One enhances the other.

 

I understand you go thru this process to see how things look . But so what? Why not just turn the max number of samples to 100 and sample radius to 300mm to begin with?

 

This is a serious question what do you see by going thru this process?

 

Also you say at that point you can see your weak areas. Once again is there anything you can do about those weak areas. arent those just the normal parts of darkeness in a scene?

 

Would appreciate a response thanks

[Justin Hunt]

Its a great way to gain understanding of what settings are doing, but your right in that once you understand the settings, why experiment over and over for every project / scene. With time you will instictly know what works and doesn't and if it doesn't then do the experimentation.

 

jhv

[SandmanNinja]

If you see weak areas, then either add more bounces or more lighting (I'd say in the form of mrSkyPortals), or adjust the multipliers of your existing multipliers.

 

I do the steps listed above pretty quickly now, and sometimes I skip around.

Like Justin said, after a while you have a feel for a scene.