Vray Sky and Environment Question

[Dave Buckley]

If i have a VRSky in the Max evironment slot, and then if i enable the GI Environment Override in the Vray Dialogue, what effect is one having over the other???

 

I assume that the environment light would be coming from the Environment in the Vray dialogue as it is an 'override' after all

[Dave Buckley]

settings attached

[Stephen Thomas]

By enabling the GI Environment override the vray sky is no longer lighting your scene. It is only providing your background and is also visible in reflections.

 

Obviously you can override the reflection aspect as well if you wish. However to use the vray sky in the way it is intended you should really leave these overrides unchecked, therefore having your background, lighting and reflections all matching and updating dependant upon your sun position.

[Dave Buckley]

cheers stef, the scene is actually an evermotion scene that i am tring to break down and understand why they have setup it up as they have done.

 

what i notice in a lot of interior scenes is that, the background plane are often done by adding an image to a vray light material?? i can't figure out why this has been done either because there are also plane lights in the windows, surely these are providing the environment light???

 

and if they are then surely the sky and the environement overrides are not needed either

[Stephen Thomas]

I quite often use a light material with bitmap for background image outside windows, whether it be a dome or a plane. Just another alternative to adding it in post really, the light material is not for actually providing illumination, just for controlling the exposure and not having to worry about it being affected by lighting.

 

The plane lights are obviously the main source of lighting, but I always use these in addition to an environment light as well as I find it gives me a faster and smoother GI calculation.

 

You're right though, with the image plane providing the background and the override set the vray sky is redundant. Perhaps it's just left over from some earlier test renders or something.

[Dave Buckley]

ok so the plane lights at windows and the environment light (whatever it may be) both work together. good. now i'm getting somewhere. and i'm so glad you said that it may be left over from previous test renders coz that was the only logical thought i had

 

finally then

 

the background plane that displays the background image . . . if there is a light outside (whether it be a sun, or just a standard direct light) should this be unchecked when it comes to casting and receiving shadows??

 

because in the scene that i originall posted both of these options were checked.

 

thanks for the help stef, but just to confirm, the light from the light material has no effect on the scene lighting whatsoever??? and when you say exposure, do you mean from colour mapping or a physical camera?? if its for the physical cam then would the light material be needed if i was using a standard cam

[Stephen Thomas]

Yes, make sure the plane does not cast or recieve shadows, though if it's a vray light material it won't be affected by shadows anyway but best to be on the safe side. I guess the light material will have some effect, but it will be fairly negligible with the sort of multipliers I normally use. You could remove it from GI calcs in the vray properties, or you could see it as adding some colour to your scene that matches the image itself I suppose!

 

I don't think I've really used this in conjunction with the physical cam before, but I imagine you would have to pump up the multiplier on your light material depending upon your exposure. Maybe you would want to exclude it from GI then, or use a different method. When I was talking about exposure above I just meant changing the brightness levels of the exterior as seen through a window, like you would in post to get it looking right.

[Dave Buckley]

you've said just about everything i wanted to hear stef thank you

 

the multiplier of the light material for the background is just a case of tweaking until the image looks as though it would look naturally

 

(however) if the exposure were correct you wouldn't be able to see out of the windows on an interior would you?)

 

but then that defeats the point of making the plane lights invisble.

 

and if you wanted to see a burnt out sky then i guess the plane lights wouldn't be needed right, you would just set the correct exposure for an interior and then the sky will blow itself out (note to self - remeber to control burn with colour mapping)

 

the plane lights on there own if not made invisible would have the same effect as a blown out sky???

 

the sky on its own without the plane lights would give the blown out windows???

 

so is the combo of both the sky and the plane lights purely and simply a method of getting a smoother GI solution???

[Stephen Thomas]

If you're using just an environment light to light an interior, the GI can be a bit patchy, the plane lights help to give a bit of a boost of direct light. You can also set your plane lights to skylight portal which means they take on the colour and intensity of the environment (vray sky or otherwise), but that generally takes longer to calculate.

 

You can of course use the plane lights on their own, but I find a mix of vray sky (or HDR) and plane lights gives a fast GI calc and a bit of colour to the external light coming in. I don't use image planes as background all the time, but they are a good way of having your external environment reflected in things like floors etc. and gives you more control over the position than simply dropping in a backgroound image in your viewport.

 

You're right about the exterior being blown out in an interior image, but I like to show a hint of what's happening outside. How much is personal preference. Also 9 times out of 10 I just use the standard vray cam, but the physical cam is a good tool to master. Especially if you have areas of your interior that get varying amounts of light. That way you can leave your lighting set up and just expose the cameras for that particular view.

[Dave Buckley]

cheers stef, i think i'm going to set up my sun and sky and leave the multipliers at 1, then setup a physical cam with what i believe to be correct exposure for a sunny interior.

 

then i shall add planes at the windows, the only value i should then need to change really is the multiplier of the plane lights to compensate for the exposure of the camera, and also the multiplier of any light materials i have in there.

 

cool, so far so good.

 

gonna throw a different one in there now, lets say i want to be able to a bit of blown out effect and a bit of the background through the window.

 

i know it can be done in mental ray by changing the transparency of the sky portals but how would i do it in vray

[Stephen Thomas]

I generally do all my blow-out or bloom effects in photoshop. Make a duplicate layer, then do a levels adjustment and drag the bottom slider up to clip out all but the highlights. Then do a gaussian blur and change the layer mode to screen (or similar). Play with the blur amount and layer transparency to get the effect you're after. You can also mask out any bits you don't want.

[Dave Buckley]

ok cheers steph i think you've helped me enough to continue with what i am doing

 

oh actually, if i use the sun with a standard cam, then am i right in thinking i need to drastically reduce the intensity???

[Stephen Thomas]

ok cheers steph i think you've helped me enough to continue with what i am doing

 

oh actually, if i use the sun with a standard cam, then am i right in thinking i need to drastically reduce the intensity???

Generally about 0.01-0.02, but on an interior shot you might want to try boosting it a bit more to get that physical cam look with the brighter exterior.

[Dave Buckley]

brilliant, however it seems i'm pretty comfortable with the physical cam settings, spent ages in mental ray learning exposure, so not letting my endless hours of learning go to waste

 

but just wanted to make sure that i was thinking correctly.

 

tomorrow i'l ask you all about exteriors

 

just kiddin stef but cheers for all the help today

[Dave Buckley]

hi again steph

 

sorry to bother you again but i am now happyish with my lighting but not so happy with how flat it looks, how can i bring some contrast back into the render???

[Stephen Thomas]

I would switch from exponential to linear colour mapping. Or Reinhard, which allows you to control the burn out. But generally I would adjust the curves/exposure in the Vray frame buffer.

[Dave Buckley]

i am using reinhard with a multiplier of 1, burn of 0.2 and gamma is set to 2.2, i will have a play with the curves as you say, is there any quick ways of adding contrast in post, e.g. duplicating layers, changing blending modes etc etc

[Dave Buckley]

heres the render so far, just a room shell

[Stephen Thomas]

i am using reinhard with a multiplier of 1, burn of 0.2 and gamma is set to 2.2, i will have a play with the curves as you say, is there any quick ways of adding contrast in post, e.g. duplicating layers, changing blending modes etc etc

I was just going on your previous render settings. Probably just adding a curves adjustment in Photoshop is easiest, there are some presets in there for increasing contrast.

[Dave Buckley]

(note to self - stop being lazy and learn photoshop properly)

 

in the mean time thanks stef, the strong contrast is perfect for what i wanted, where have you been all my life

 

good stuff stef

[Dave Buckley]

oh and stef, the link in your sig, www.glo3d.com when i click it it opens but then when i click on either the US or the UK it opens up outlook as though i have just clicked "send email" and the emails are directing to *******@rmjm.com (***** being the peoples names) is this right

[Dave Buckley]

last one stef, i promise

 

this is the last thing that is confusing me (for now)

 

i have copied my vray sky to the material editor, now if i check manual sun node and pick my sun in the scene, i then get access to the sun intensity multiplier, however i also have an intensity multiplier for the sun in the modifier panel when the sun is selected.

 

does one override the other???

 

what effect does one have, i know that if i change the intensity via the material editor (sky) it stops my scene being so bright.

 

but i have also seen some scenes where the intensity has been changed in the mat editor with manual sun node checked, and also at the same time the sun itself has had the intensity changed to a different value

 

i just need some clarification on this as to whether both are used as another method of balancing out the light, or if the vray sky overrides when manual sun node is checked, and whether i need the manual sun node checked at all

[Dave Buckley]

and the highlighted areas i am talking about

[Stephen Thomas]

oh and stef, the link in your sig, www.glo3d.com when i click it it opens but then when i click on either the US or the UK it opens up outlook as though i have just clicked "send email" and the emails are directing to *******@rmjm.com (***** being the peoples names) is this right

Yeah, we haven't set up the website fully yet so at the moment it just has contact details. At the bottom there should be links to some images on flickr and animations on vimeo though. And we are the in-house team for RMJM architects.

 

last one stef, i promise

 

this is the last thing that is confusing me (for now)

 

i have copied my vray sky to the material editor, now if i check manual sun node and pick my sun in the scene, i then get access to the sun intensity multiplier, however i also have an intensity multiplier for the sun in the modifier panel when the sun is selected.

 

does one override the other???

 

what effect does one have, i know that if i change the intensity via the material editor (sky) it stops my scene being so bright.

 

but i have also seen some scenes where the intensity has been changed in the mat editor with manual sun node checked, and also at the same time the sun itself has had the intensity changed to a different value

 

i just need some clarification on this as to whether both are used as another method of balancing out the light, or if the vray sky overrides when manual sun node is checked, and whether i need the manual sun node checked at all

You only need to check manual sun node if you want to use a different type of light to control the sky i.e. vray sphere or target direct. Otherwise the vray sky will automatically use any active vray sun in your scene, so you could have a couple set up for different times of day and toggle them on and off.

 

I'm not really sure about the dual intensity controls though.

[Dave Buckley]

so if i'm using a vray sun, i do not need it checked, and also if i am using vray sun and decide to change the intensity in the scene, it becomes not pysically correct right?