glass material and Sketchup sun postiton

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sgtslick921
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Joined: Fri Dec 27, 2019 9:21 pm

glass material and Sketchup sun postiton

Post by sgtslick921 » Fri Dec 27, 2019 9:32 pm

I'm a noobie just learning Twilight Render. I'm trying to render an interior bathroom with the sun coming thru a single window and some TR lights over the vanity. With shadows turned on the sun can be clearly seen coming in thru the window in the model and casting light on the tile floor. Using TR glass material applied to the window glass (I've attached a screenshot showing the SK model, materials setting window for the glass and the prelim render window.
Clearly the sunlight on the floor is not rendered and I'm not sure why it's not. Was wondering if someone might be able to figure out what I could be doing wrong. Thanks much for the help.
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Chris
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Re: glass material and Sketchup sun postiton

Post by Chris » Fri Dec 27, 2019 11:15 pm

You need to use Architectural glass. The regular glass material combined with the thickness of your window is resulting in too much refraction.
There is also an option in the TWR Environment editor to "Correct" the sun position. You may need to enable that as well.

Fletch
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Re: glass material and Sketchup sun postiton

Post by Fletch » Sat Dec 28, 2019 10:22 am

In your case, glass is not needed at all and only increases render times. But if you desire to have the glass - do as Chris suggested.

Please watch all Video Tutorials for Twilight Render.



See the FAQ
Subject: Light through a window...
admin wrote:
Sat Sep 12, 2009 4:42 pm
How to get the sun shining through your windows:
  • Be sure all windows are only modeled with a single pane of glass.
  • Be sure you have applied a material to the glass using SketchUp's materials, such as the typical "translucent_glass_grey" or whatever
  • Be sure you use the Twilight Material Tool to click that glass material on the windows and apply the Architectural Glass>"Common" or "No Shadow" set glass material color to white and alpha to Zero.
  • Set the sun in SketchUp to cast as much light as possible into your room... the more light the better.
  • Apply material templates that are appropriate to your other objects.
  • Render a small test render with Easy01-Prelim
  • Adjust tone mapping exposure in the camera panel of the Render Window if image is too dark.
  • When happy with camera, materials, etc. Render test render at 800x600-ish on Low or Medium easy settings.
  • When happy and ready for the "final" render on Easy09 progressive. This will give you best results with so little light.
Or, the classic "tricks" of placing an invisible light emitting plane outside your window, or adding spot lights outside to cast in light... and these work fine in Twilight, but are not necessary and take some tweaking/patience.

For inserting background, it is recommended to use a spherical sky image. But one may also try the old "picture on a plane" trick, at some significant distance from the window so that it will get enough light and not block light coming into the space through the windows. The other way that gives best control is to render with physical sky, then render an alpha mask of your scene after hiding all glass. This will let you mask in a hi-res background in your photo editing program. See the Twilight User Manual Mask Section on page 8.


***FOR RENDERING WITH EASY 09 AND EASY 10 RENDER SETTINGS ONLY***
There is also something in Twilight called a "Sky Portal" material.
How Do I Use A Sky Portal?
Install the Sky Portal Materials for Twilight Render from here.
Download a Sky Portal Test Room here.

The Sun and Sky cast light rays onto your model in a random way.
If some of those rays make it through an opening and bounce around inside your model, they will light up your scene.
Low render settings are fast because they tell the lights not to cast a lot of light rays. Therefore they will not work well for your scene where you are attempting to light an interior with light only coming from the Sun and Sky. You will need higher render settings, so that more rays are cast, and therefore, hopefully, more of these random light rays make it in through the openings in your model.

If only you had something that told the Sun and Sky exactly where the openings into the model were, and acted like a "door-man" for the light rays saying "come on in here, guys"... that would be useful. ;)
A Sky Portal is just that. It is a plane that covers any opening into an interior model.
When working properly it will take ALL rays of light from the Sun and Sky and bring them thru the "Sky Portal"
  • This plane must have the Front of the Face facing IN towards the INSIDE of the model.
  • Pick any color in SketchUp's material pallette and paint the Front of the face of that Light Portal Plane.
  • Now in SketchUp's material editor rename the material something like "Light Portal" :)
  • Now with Twilight's Material Tool apply the Sky Portal Material definition from the Library called "Light Portal"
  • Now when rendering with any method it will be working with all light info possible from only the Sun and Sky light outside.
  • Easy09 would still be the render method of choice.
  • However, even if rendered with "Easy 02 - Low" you will get high quality lighting, considering how little light set up has been done.
  • Rendering time will increase significantly for non-progressive render methods because of all the light bounces now being calculated, so start with the lowest render setting possible and work your way up when using light portals. Conversely, render times for Easy09 or 10 may actually decrease...difficult to quantify this
Keys to Sky Portals:
  • Use the least number of surfaces possible... no curving surfaces!
  • No light must be able to enter from the Sun and Sky into the model from any other way except through the Light Portal.
  • If 3 windows are on one wall, be sure to use a single plane to cover all 3 windows... the fewer portals the better/faster.
  • Be sure the portal covers completely/intersects the window or opening... not a crack of light may enter the opening without first going through the portal.
  • Be sure the face is pointing into the model... the direction you want the light to travel from the sun and sky to get into the model.

sgtslick921
Posts: 7
Joined: Fri Dec 27, 2019 9:21 pm

Re: glass material and Sketchup sun postiton

Post by sgtslick921 » Mon Dec 30, 2019 1:46 am

Guys, thanks so much for all the helpful information and advice. I’m very grateful.
Can’t wait to try it all out tomorrow. (Sunday night when I’m reading this).
Cheers!

sgtslick921
Posts: 7
Joined: Fri Dec 27, 2019 9:21 pm

Re: glass material and Sketchup sun postiton

Post by sgtslick921 » Mon Dec 30, 2019 9:24 pm

Wanted to post a new render thanks to the tips you all gave me. Turned out pretty well. One problem I noticed is the one wall with the vanity lights don't show the SKP material (subway tiles) which are clearly visible in the SKP view window. They don't render in Twilight Render.

Can't figure out what needs to be done to get them to render. Any ideas?

Thanks.

sgtslick921
Posts: 7
Joined: Fri Dec 27, 2019 9:21 pm

Re: glass material and Sketchup sun postiton

Post by sgtslick921 » Mon Dec 30, 2019 9:27 pm

Screenshot didn't post. May have been too large. Here it is.
Screen Shot 2019-12-30 at 4.21.56 PM.png
Screen Shot 2019-12-30 at 4.21.56 PM.png (794.05 KiB) Viewed 1863 times

Fletch
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Re: glass material and Sketchup sun postiton

Post by Fletch » Tue Dec 31, 2019 10:26 am

Check - face is reversed
Please watch the video tutorial series. It will save you hours of frustration.

Possibly could Lower power of light sconce, increase exposure of camera. See Video 5 in the "6 Essentials" series linked above.

Reduce any white surface to 85-90% grey. There are no pure whites in real life.

Try "sun and sky" settings to eliminate the light flares with so few lights, or disable caustics in Easy 06. (see Tips and Tricks tutorials on forum for instructions) Light leaks and flares are also quickly eliminated when surface material brightness is set properly (physically accurate) - refer to comment about white above.

Try rendering with Sun and Sky "Medium" (02) render setting to see if it renders well.

For final quality, use Easy 09.
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