Shaderlight forums

Hi EGIE,

From what I remember from past discussions, I think the consensus was that you shouldn’t use the SU ground.  Because it doesn’t reflect light so your undersides (balcony ceilings, etc.) are too dark.

If you turn off the SU ground shadows and add your own ground plane as actual geometry that should fix the issue and give you greater control over other ground variables like slope, reflectivity, variable depth, etc.

Not what you are asking for but a relatively simple solution all the same.

Cheers,

Andrew

Hi Andrew
Thanks for your fast answer - you what you say is correct but now there is a dilemma for me :-(

Within Shaderlight I avoid any kind of ground geometry, like gardens, roads, etc ...  Once I use ground geometry in SL, all down facing faces will get almost black, which is an intolerable bad renderer result.

The only render method, which provides good daylight LIGHTING results in SL is, placing any house on SkUp ground - but allways with correapondending shadows and ambient on it at least. Without these, the render result will be really terrible.

Shaderlight still has this lighting malfunction which I had posted about a a few times so far.

https://artvps.com/index.php/discuss/viewthread/2725/

For this Bug I have two work arounds, the first one is to use an other renderer like Render[IN], Twilight or Brighter3D for example and the second one is, to render twice in SL - one render without ground geometry and a second render with ground geometry. - These two SL renders than have to get merged in PSD.

To be honest, I do not understand that no one seems to be angry about this basic lack of Shaderlight´s lighting skills. Solving these issues would be much more important than to develop section cut render for example - because also there, the lighting does not really work well…

hmm - as you see, there is serious a dilemma for me ;-)

Best, Egie

I see your problem.

What happens if you use different materials for each side of the ground plane: paint the underside of your ground plane perfectly clear?  In theory, the top surface will reflect light/receive shadows and the light from below the model should pass through the ground plane the same way it does for the SU ground.

I don’t have time to test this right now, but if I get around to it before you do, I’ll post the results.

Good luck.

Thanks Andrew
an intelligent proposal which I have tested immediately - Unfortunately without success also
(although I’ve made the bottom of the ground white and even tranparent!!).

This problem is known to the SL support - but there is no solution so far and I hope that a future version will have fixed this PRIO No1 ERROR.

I´ll add the testing screeshot of your proposal as well as a render comparison from SL to Render[IN] which both are done with the same model with grond geometry out of the box. No problem for any renderer else than Shaderlight…

I wonder why this does not bother anyone else here ????

Best, Egie

I can only speak for myself, I don’t do a lot of architectural renderings so this issue hasn’t impacted me much (until now - now it’s bothering me).  Your examples are very dark.

Curiously, in your example above, were you using global illumination?  It looks like nothing is bouncing up on the ceiling at all.

When I ran a test with ground geometry I didn’t have the same degree of issue.

Settings:
- Physical Sky
- Sketchup Background
- default material on both sides of the ground plane.
- global illumination
- full quality

I also went a step further and added skylight portals over each of the openings.  This resulted in (as expected) brighter interiors, and slower render speed but definitely eliminates the dark ceilings.

Hi Andrew - thanks so much for your testings !!!

I have created the dummy scene below. Both scenes are rendered with the global illumination setting.

Picture 1 is a building without ground geometry - all light conditions are ok!

Picture 2 is extended with Ground geometry and in addition even with a light portal
This result is a real catastrophe and completely unusable.

Picture 3 is the same as scene 2 but rendered with Render[IN] - “portals” or settings like “Global Illumination” are unknown there - btw, also for interiors…

Since not all buildings stand on a flat ground, I can use Scenario 1 only in few cases - So I need to evade to alternative renderers.
Also using Portals - which is already annoying for interiors - is not suitable for complex geometries and often causes very strange light reflexes.

This all is quite bad because the entire workflow in the company I work is a SL workflow right now…

Somehow Shaderlight (which I still love !!!) is like a car, which gets already sold, although it´s engine is not yet developed but instead a coffee cup holder for the back seat! - There are set false priorities I maintain.

Best, Egie

Can you share your “dummy scene” model?

... emailed the file to you -  thanks!

Okay so part of the issue is quality setting.  If you look at your setting for Render[IN] your setting is “High”.  The setting on Shaderlight is Q5.  The quality setting determines how many bounces the photons make.  If you look at image A (Q5) you’ll see the black ceilings (unaceptable as you pointed out), but in image B (Q10) the ceilings are better illuminated because more of the light has bounced onto them.

The other thing I noticed in the Render[IN] image is that the contrast between shadows and the face of the building is much lower, which suggests that the Render[IN] light source may not be as bright or direct.

I’m not sure if you remember a post a year or so ago where I thought I had found a way to make a soft glowing cube by using a transparent material on the inside and self-illuminating material on the outside and a light source within.  At first, it appeared to work, but when other light sources were added to the scene the effect stopped working - the reason it worked on its own was that the amount of light coming through the material was reduced and the longer exposure resulted in that soft glow where the contrast between shadow and light was less.  The same thing may be happening here.  The bright sun reflecting off of the building surface is reducing the exposure “time” requirement so the shadowed areas appear darker.  If I’m right, then if the light is softer in the Render[IN] example, it would have required a longer exposure and made the shadows appear lighter.

To test this theory, I’ve used a softer light source (cloudy volcano) in image C. The result as you can see is even better. Finally, in image D I’ve tried an even darker light source (golf course evening) and you can see that the contrast is reduced further.

I’m going to try to find a building with similar structure to photograph it—From memory, I would argue that C & D are closer to real world than the Render[IN] example (the back-most corners should be relatively dark unless the sun is perpendicular to the balcony), but we think it should be brighter because our eyes adjust for the point we are focused on (same argument we always have regarding interior scenes and windows).

I’ll post the photo when I have time to find/take one.

Hope this helps as a starting point to a solution.

Cheers,

Andrew