Render times?

[RevitGary]

Anyone know why I am not getting any cast shadows from my new portals?

I have been trying every setting I can think of with no luck

[RevitGary]

Ok i think I have it figured out. I was using the "emit direct photons" setting because Iwanted faster speed. It seem that this does not give the shadows I was looking for. going back to " look up using fg rays" works fine. i think im still testing

[RevitGary]

ok attached are my 2 solutions the one I have been using and the new one with the new portal settings.

 

The new settings dont give anywhere close to the results of the old one.

 

Things are very dark and the ceiling is losing a lot of detail.

 

Does anyone else have similar results?

Am I doing something wrong?

 

Thanks as always

[RevitGary]

Well I keep plugging away and I think I found the problem. I had environmental physical scale set up to "unitless... It needs to be set to physical units.

 

So if anyone is still reading my ramblings

 

one more question

 

Thorsten says "emit_direct_photons: You can optimize the Shadow to FG-Ray or Photon Map (very fast)"

 

Does that mean I can use the "emit direct photons " setting then some how set the shadow ray extension setting to cast FG-ray shadows? How is that done.

 

I am most interested in the fastest speed possible. with good results

[RevitGary]

I have been using the Environmental portal shader seems to be working quite nicely. I noticed the error in the MR message box

 

"PHEN 0.3 error: Shader 'mia_portal_light' must be applied to a VISIBLE rectangular area light to work correctly!"

 

Anyone know what this means? This seem to be working ok so I dont if the error matters.

[wannabeartist]

Hi Gary,

 

I'm battling with the portal lights too.

 

For your latest question, I'm not sure how you got to that with Max, but with other packages you actually have to plug in an area light for the portal light and if you forget to make that visible, you'll get exactly that error.

 

From the docs (mr.architectural.shaders.pdf):

 

"The mia portal light shader should be applied both as light- and photon emitter shader on a rectangular area light. The mental ray light instance must be set to be visible (this is a technical requirement for the portal light to be able to \block final gather rays. If the light actually is visible or not in the rendering is instead handled by the shader)."

[keyston]

Hi, Im new here.

Im also trying to find the best and quickest solution for interior renders. at the moment Im rendering a library/computer classroom about 13 x 13 metres. Its quite a complex scene with a lot of colours and glossy mats and a few plants. each camera view is taking upwards of 5 hours. ive got 18 lights in the scene, ( daylight, 2 sky portals and 15 photometrics. )

After a lot of forum research, different tutorials and trial and lots of error Im getting close to the right lighting solution.

I will try the suggestions in this thread when the batch render is done.

I thing with my scene is the windows are irregular shaped and the walls protrude on both sides, causing me to have to place the portals about half a metre from the windows. Is this a problem? and aslo is it at all possible to make sky portals an irregular shape.

ie; clone the window planes or something? This to me would seem logical considering todays architecture things arebt always square or rectangular.

[RevitGary]

"causing me to have to place the portals about half a metre from the windows. Is this a problem? "

 

No if it is an indoor view. You can make one large portal to cover many windows.

Just think of portals as big square lights.

 

 

"and also is it at all possible to make sky portals an irregular shape."

 

I dont think so and no reason to.

 

 

 

Why dont you post some images

[Crazy Homeless Guy]

big square lights.

 

Big square area lights though, so they can have huge effects on render times if not used carefully.

[Justin Hunt]

It helps if you set the attenuation on the lights.

 

Think about how many portal lights you really need, does every window need a light? If the sun is streaming in some of the windows then there is no need to add portal lights to those, maybe only put one on the windows not dirctly light by the sun.

 

For really large or odd shaped area lights, a self illuminated , FG generating plane renders quicker, sure the shadows will be more diffused but thats ok. Just remeamber to make them invisible to the camera and/or invisible to reflection and refractions.

 

jhv

[keyston]

hi, thanks for that. so you think if theres enough sunlight coming through the window I dont need the sky portals? they are both on the same wall facing east.

Ive only recently started using portals in the windows as I read it in the mr help in max help, and most of the tutorials ive seen say they need to be the same size as the window and within a few inches.

anyway my renders have just finished and id like to post them here pre ps4 to get your opoinions.

thanks again for the quick responses.

[Justin Hunt]

from what I remeamber it also says that they work best ifthe mrsun doesn't shine through them as it will overpower the portal light.

 

With regard to the size and placment of the portal lights, if you make them too big and are too far away from the window then photon samples will be waisted by hitting the outside wall and bounce away from the scene. If they intersect geometry you can get artifacts and emission errors.

 

They can be placed inside the room, which will contain all photons, but wont illuminate the window frames from the outside. If they are placed too far inside, then the lighting will look odd on the ceiling and floor. ie the highlight from the window will be too far away from the window.

 

So inside our ouside? thats for you to becide which works best for you. Size? I prefer to have them slightly smaller than the window.

[keyston]

yeah, ive moved the sun away from the windows since ive been using the portals. but to be honest I havent noticed much difference between the direct sun in the windows and using the portal lights in this scene, except the portal lights seem to take longer to render.

I might revert to the direct sunight again, I havent tried that with the photon radius adjusted to the window size yet.

and you click targeted in the daylight dialoue and also the light lister right?

Do I need to position the compass closer to the windows?

Sorry if my questions seem a bit dumb, I havent slept since yesterday and Im determined to show people in here that mentalray can produce as good or better renders than vray without taking forever.

 

P.s. how do I upload larger pictures to here, I rendered at 800 x 600?

Thanks gurus

[keyston]

hey hustin, I just noticed your from brisbane.

Im from perth but live in java atm.

gday

[Justin Hunt]

in the mrsun settings- under mr Sun Photons, check Use Photon Target, and set the radius to apropriate size. Yes move the compass so that the windows fall within the radius area.

 

To upload an image, use the "Go Advanced" button and then use the manage atttachments to upload images.

 

Feel free to post your render settings too

 

Gday from Brisbane

[keyston]

here is the library/ computer class.

the white artifact on the bamboo is because its vue instance and need to adjust the settings.[ATTACH]40440[/ATTACH][ATTACH]40442[/ATTACH][ATTACH]40443[/ATTACH][ATTACH]40444[/ATTACH]

[RevitGary]

Are you using gama?

[Justin Hunt]

agree with the gamma and you also need to adjust the exposure control.

 

I'd also suggest adding geometry to the light fillings, the hot spots on the ceiling look odd.

 

With a bit more tweaking this will be great,

 

jhv

[keyston]

heres the last 2 cameras and render settings.

I had gamma turned on and set to 2.2 default.

Why does max ask to disable gamma when you use photometric lights?[ATTACH]40456[/ATTACH][ATTACH]40457[/ATTACH][ATTACH]40458[/ATTACH][ATTACH]40459[/ATTACH][ATTACH]40460[/ATTACH]

[keyston]

last of render settings[ATTACH]40461[/ATTACH][ATTACH]40462[/ATTACH][ATTACH]40463[/ATTACH]