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minotto

Interior space lit entirely by natural daylight (Heliodon tool)

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I've been trying to find the best settings for an interior that is lit by the Heliodon, Custom Renderworks rendering and a HDRI background, that is only natural daylight, no artificial lighting present.

 

Has anyone found a good setting for this?

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For interiors with daylight you will need to set GI bounces very high.

That will take render time but otherwise your GI is too dark in shadowed areas

and unnatural. You can fake a bit by using Ambient light if you wish.

 

The more window area and incoming direct light, the easier for GI and faster.

 

You can try light portals for window areas if you want to concentrate GI

calculations to the interior.

 

 

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Thanks for the tips, zoomer.  I've attached an image to show my problem. It seems though there is some other competing light source.  I've tried various settings where the heliodon is on or off, adjusting the light output of the HDRI background, changing the lighting options but continue to get these hot spots and the same general lighting angle coming through the openings. Not a problem with Open GL, just the Renderworks settings.

 

daylight.jpg

Edited by minotto

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Like when taking interior photographs, the problem is that the outside is much much brighter

than the interior, and window backgrounds in your perspective will totally wash out.

So I think the halo around your overhead lights on the right may be just the first bounce of

indirect light from the environment floor.

As VW has no more overall brightness slider, you should use a camera and adjust exposure

in camera effects by time/ISO/aperture like a real camera to get the brightness you want.

 

As for the halos, you need something to clamp the brightness to fit in your RGB foramt,

like Reinhard or similar. Unfortunately in VW RW you don't have access to these settings.

 

But very important is the use of correct material settings for absorbtion.

Even white walls will only reflect about 70% of light in reality. So white plaster means a bright

gray for material settings, otherwise it will not absorb light and GI bounces forever.

So especially something darker for the ground materials outside.

 

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Another thing to keep in mind is that you have shadows coming from multiple exterior sources.  The Heliodon and the HDRI image.  If the HDRI has a sun spot in it, it will cause highlights and shadows like you are seeing.  Be careful which HDRI you choose as to not overlap, try something that either has a hidden sun, or overcast.

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Another good way to solve this is to add a Renderworks camera to your sheet layer viewport, then enable Exposure as a camera effect. This has worked well for me recently when I'm trying to only use "natural" light sources.

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Josh,  I've been using HDRI Sky Day Mostly Sunny.  What other options would you suggest as far as a hidden sun?

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5 minutes ago, minotto said:

Thanks Jim.  What exposures would you suggest for the camera effect?


I usually leave the ISO alone and mess with the aperture timing. i think /60th is a minor bump, /30th is a more significant one. To play with this though, make sure your renderworks style has camera effects ernabled. Also: you can reduce things like curved geometry and anti aliasing quality for the test renders, so you don't have to sit through the whole high quality one just to check the lighting.

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Old photographer rule, in german :

"Sonne lacht - Blende Acht"

(Iso 100, 1/125s)

 

Sun is shining (laughing) - Aperture 8

 

 

For interiors, you will mostly need :

 

- larger aperture (=lower number)

or

- longer time

or

- higher ISO

 

to make it brighter as there is less light.

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10 minutes ago, minotto said:

Josh,  I've been using HDRI Sky Day Mostly Sunny.  What other options would you suggest as far as a hidden sun?

 

 As for the HDRI you are mainly looking for any HDRI image with from within VW or on the web that does not have a strong spot in the sky.  If there is a haze around the sun, that will soften the shadows it casts.

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For interiors, I only use daylighting and a large GI bounce setting.

Never tried portals so far. I don't use HDRIs, just physical skylight.

But that is a matter of taste.

 

For the brightness,

Aperture for me is something to control DOF and so the character of the photo (simplified).

So, like in real world still photography , I always used shutter speed automatic at a given film ISO

and a chosen Aperture.

 

For rendering, I set my Aperture for potential DOF, if activated,

and play with either shutter time or ISO to control my brightness to my liking.

(Shutter time shifting doesn't matter, as longs as I don't need motion blur)

In Modo and/or Vray I also set some subtile clamping by Reinhardt to control highlights.

Edited by zoomer

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Thanks everyone.  The aperture/ISO settings in the camera definitely made a difference.

 

Just wondering though, it seems the heliodon doesn't have as much of a dramatic effect with Background RW settings as in Open GL when doing solar studies.

When setting the heliodon to say 11pm, eliminating a RW background or setting one to night and turning off all environmental lighting in the lighting settings except indirect reflections, i'm still getting light coming in the windows reflecting off surfaces.

 

Why is that? 

Edited by minotto

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The HDRI sky backgrounds pre-date the Physical Sky background, which is coupled to the Heliodon time of day and will repsond to that.  You might try the Physical Sky background.  Also the built-in RW styles for interior use a background with the brightness cranked up to 400% to get more light into a room.  The Heliodon has a brightness field in the Obj Info palette that you can use to increase it's output.  Also the built-in Glass Clear texture has the Portal option turned on in the texture Indirect Lighting settings, which helps quality for interiors lit through glass windows.  Hope this helps!

 

The physical sky background also has a saturation parameter that you can use to reduce the amount of color from the sky, if you want it more monochromatic.

 

Edited by Dave Donley

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