physical sky / custom background

[neko]

i'm sure someone is going to give me a simple answer to this dumb question, but i'm getting frustrated with something that should be quite easy.

 

i'm trying to use a custom background sky image with the MR physical sky, and each time i try to use one, the background goes black (but the physical sky is still lighting the model).

 

i've checked the photographic exposure controls, i've been searching in the rendering preferences, but i can't seem to figure out why this occurring ?

 

if i switch the custom background off in the material editor, the physical sky background is fine.

 

anyone got any ideas ? much appreciated

[neko]

i've also tried three or four different images (JPG, TGA) and they all fail

[Virgil Johnson]

Starting simple...

 

If you are using a bitmap go down to the output rollout and increase the output.

It makes the image brighter.

 

Just my first guess.

 

I have others.

 

Virgil

[Virgil Johnson]

and oh

if you notice a horizontal band across the bitmap go to the daylight setting and set the haze horizon higher

 

that might solve that

 

just another guess

[neko]

thanks for the guesses virgil.

 

it's definitely not the horizon or the output levels (not 100% certain of that though). most of the time i am fine with the physical sky alone, but this should be quite simple.

 

everything i read on it seems to imply that anyways !

 

the mapping for the custom background image under the physical sky is an environment map (set to screen).

[Virgil Johnson]

you have checked the presets in the photo exposure?

bright sunlight or whatever?

 

as far as the output (I am talking in the bitmap section in the ME)

I find 10 or twenty works well

but sometimes I have found that I need to go 50 or even 60

 

you could go back to good old logarithimic exposure

be sure to check the exterior daylight box

and see what happens

[Virgil Johnson]

btw

you have told Max to use the custom bitmaps?

checkboxes in the ME and in Environment

[neko]

appreciate all the suggestions virgil - i'm going to look at output levels again before i waste anymore of your time.

 

i did try setting it back to logorithmic exposure (from photographic) - that didn't help either.

 

it may well be output levels after all, since when i replace the MR physical sky with a simple background environment map, it still doesn't work.

 

i'll let you know...thanks

Edited April 19, 2009 by neko

[Virgil Johnson]

not wasting my time neko

i am beating my brains out learning Revit and I need a break now and then

 

just to be sure we are on the same page...

 

did you drag and instance of the physical sky from the environment slot to an empty slot in the ME and edit it from there?

 

that is where you can get at the bitmap parameters along with other parameters of the physical sky

 

it is in the bitmap rollouts that you control the output

 

but maybe you have already done that?

 

Virgil

[neko]

not wasting my time neko

i am beating my brains out learning Revit and I need a break now and then

 

just to be sure we are on the same page...

 

did you drag and instance of the physical sky from the environment slot to an empty slot in the ME and edit it from there?

 

that is where you can get at the bitmap parameters along with other parameters of the physical sky

 

it is in the bitmap rollouts that you control the output

 

but maybe you have already done that?

 

Virgil

 

yes - done all that.

 

i'm now thinking you might have been right in the first place....will fire up max now and look closer at output levels.

[neko]

virgil - you were right. i need to understand output levels a bit more. i had been adjusting it, but not the RGB levels as well.

 

the frustrating thing in this exercise now, is the realization that the custom background is not reflected in the scene (water). it suggested as much in the help menu.

 

not sure what the advantage of a custom background is then ???

[Virgil Johnson]

Paul

 

It will reflect.

 

Use a spherical map for better results.

 

Get a camera angle that picks up the reflections.

 

look at the attachments for examples

[neko]

you're a good man, virgil.

 

i also got it to work as a reflection map in the water, but there are lots of other reflective materials.

 

confused why a screen map won't work, but will try a spherical map, thanks

[Virgil Johnson]

The spherical map works like in the olden days when we had to build a sky dome and put the map on it.

 

Sometimes I have to have some kind of "billboard" with a map so I get the reflections that I want. (Especially good for reflections in windows.)

 

The screen is more like a background or backdrop.

 

Glad it worked out.

 

In life you just can never give up.

 

Virgil

[neko]

The spherical map works like in the olden days when we had to build a sky dome and put the map on it.

 

Sometimes I have to have some kind of "billboard" with a map so I get the reflections that I want. (Especially good for reflections in windows.)

 

The screen is more like a background or backdrop.

 

Glad it worked out.

 

In life you just can never give up.

 

Virgil

 

that's sort of how this all started - i was going to just make a dome or a billboard, but thought this was how all the cool kids were doing it these days.

[salf]

I was about to open a new thread regarding the same issue.

 

I read this, but it's not working properly on my end, maybe I missed something.

 

Basic model, a tall building, curtain wall, mr sun and mr sky, mr photographic exposure.

 

So far so good, now Im assigning materials, A&D thin glass for the curtain wall, not so much reflections, and the mr sky in the background it's too dark for the kind of sun I have, so I use a sky jpg as the environment, hit render and:

 

-still no reflections, and the background is now pitch black.

 

I switched to LOGARITHMIC EXPOSURE CONTROL, click the exterior daylight option and hit enter:

 

- I start to get the sky bitmap reflections, but the background stills black.

 

I read this thread, I modify the output amount value from 1.0 to 1.2, and with this value I get the reflections I want in my glass, however no background, just black.

 

I only start seeing the background with an output value of 60 or something (and its not even the blue sunny sky form the picture, but more like gray), however, anything higher than 1.9 in the output value will make the reflections bright white, like having a mirror in front of a burning white wall. So there's no sense in going higher with the output amount.

 

Now, all that was under Logarithmic Exposure, I switched back to mr photographic exposure

(with the last output amount setting of 60) and the background is black again and I lost my reflections (the bright whites ones), so it doesn't works at all with mr photographic exposure.

 

How to get a nice background and reflections then?, I'll work on logarithmic exposure, I'll set the output to1.2 so I get the reflections I want, and compose a background later in PS, but I know something's wrong, I should be able to do it in MAX directly without issues.

[Tommy Burns]

Try this

 

In Mr photographic exposure click unitless in physical scale and put in an amount of 90,000. I think this is what your missing let me know if it works.

 

Tommy

[Peter M. Gruhn]

Just found the answer on the net. Now to try to relate what I had to do. It involved NO output adjustment. I was always suspicious of that.

 

On the MR_Sky (part of daylight system) turn of Aerial Perspective.

Turn off exposure Process Background.

Put bitmap in "use custom background map" slot on physical sky environment.

Remember to actually turn that on.

Leave the rest of the environment as Inherit from Sky.

 

For the bitmap I am using I use (first approximation) cylindrical with tile B 2, offset B 0.24. Your settings will depend on whether your map it spherical or cylindrical or what; on whether or not your sky starts at the horizon and goes only up or if you include all the ground too.

 

One fella on the net had you put the background map in the haze slot of the environment. I wasn't happy with that.

 

I think that's all. I kept pursuing it because so many of the solutions I read sounded wrong, no matter if they "worked". The docs say "oh just put a bitmap in there and you're good to go." Well, not quite that simple but I felt like there was a solution which wouldn't sound like a kludge.

[gspoutnik]

Hello just put mr exposure to physical scale unitless to 91000

drag and drop Mr sky to MEditor as instance and put a bitmap in "use custom background ".

That's all

[Jennifer]

With the mr Photographics exposure the problem is that the background image is not illuminated. A properly scaled HDRI is usually visible, but not a low dynamic-range image. The Unitless and 90,000+ is a good approach, as is adjusting the Bitmap shader's Output.

 

You can also wrap the background bitmap in a Utility Gamma & Gain shader to scale the map. Click the Bitmap type, choose Utility Gamma & Gain, and Keep the old map as a sub-map. Set Gamma to 1.1 and disable the Reverse Gamma setting. You can now adjust the brightness independent of anything else. The Unitless (Physical Scale) setting will scale all non-photometric lights as well as the background. Always use the "Process Background and Environment Maps" option in the exposure control.

 

Jenni

[ashtree]

With the mr Photographics exposure the problem is that the background image is not illuminated. A properly scaled HDRI is usually visible, but not a low dynamic-range image. The Unitless and 90,000+ is a good approach, as is adjusting the Bitmap shader's Output.

 

You can also wrap the background bitmap in a Utility Gamma & Gain shader to scale the map. Click the Bitmap type, choose Utility Gamma & Gain, and Keep the old map as a sub-map. Set Gamma to 1.1 and disable the Reverse Gamma setting. You can now adjust the brightness independent of anything else. The Unitless (Physical Scale) setting will scale all non-photometric lights as well as the background. Always use the "Process Background and Environment Maps" option in the exposure control.

 

Jenni

 

 

This is very useful, thank you.

[RevitGary]

Is it possible to use an hdri for illumination and not have it show up in the render?

 

I am assuming if I render to a TGA I can then delete the background hdri image then paste in whatever I want.

 

Can this be done without the photoshop post work?

[raziel]

Is it possible to use an hdri for illumination and not have it show up in the render?

 

I am assuming if I render to a TGA I can then delete the background hdri image then paste in whatever I want.

 

Can this be done without the photoshop post work?

 

Try using the HDR only on the Skylight map and dont put it in the enviorment slot.

[sershx]

@Peter M. Gruhn,

Can you please show somewhere step by step your settings, because either im a tard or i have missed something... thanks