Sky Reflections & Interior Brightness

[Sam Parish]

I have been working on a basic render of a project I am working on, using the Cineware render engine. I'm really struggling to get the result I am looking for am wondering if anyone has any tips on how to get reasonable renders.

I have an elevation with a balcony and a semi-open door.



What I am looking for is sky reflections in the glass and some sort of illumination of the interior so it is not completely black. I have inserted a window light behind the window to try to give the room additional light but I'm getting nothing. I assume I would need to massively ramp up the GI to get the inside to be not dark but no matter what I do the inside remains really dark. The entire gable end to the right of the above image is a window so the inside should at least be mildly visible.

I couldn't seem to get anywhere with sky reflections. I tried HDRi Skies which really didn't work (couldn't get the shadows and the HDRi to work at the same time) I modified the Outdoor Daylight Fast (Physical) render settings and following the advice of Erwin in this post https://archicad-talk.graphisoft.com/viewtopic.php?f=3&t=61848&hilit=sky+reflection and it feels closer to what I want but the glass part that now has cloud reflections is also super see-through.


I would have thought it should be the other way around, the reflections being less see-through and the inside being brighter.

I'm using the clear-fast glass if that makes a difference. I'm wondering if there is a setting or something that I am missing or if maybe this just isn't how it would look and the inside would be very dark from this view.

If anyone has any hints and tips they could share it would be greatly appreciated.

[Erwin Edel]

The glass is see-through due to refraction. Your projection is looking straight at the building, if you look at the building from an angle, refraction will cause more reflections.

For interior lighting there is a 'general light' lightsource in the library you can use where you can have the option turned off that reduces intensity with distance. This creates a nice and even lighting for interior and doesn't take a lot render time. I typically put one of these in a living room at about 1.5 m above the floor.

[Sam Parish]

Thanks Erwin,

I will give this a try.

[Sam Parish]

I had a go with the internal light and this has been a really big help, this is exactly what I was looking for to give a boost to the internal lighting.

I'm still having trouble with the glass, reflections.

I took a shot from an angle and it looks better but I would still expect to see more sky in the reflection.

I then repeated the straight-on shot and though the light reflection of the sky is there, the rear window to the right of the shot seems to fully reflect the sky and clouds but the front one without has less of a reflection, I would have thought this would be the other way around?

This is definitely much better and the reflections of the sky are working but I just wouldn't expect to be able to see so clearly through the glass. I did another image with the doors closed as I thought maybe the reflection from the door leaf behind was messing things up but the inside still seems too visible.

You are right thugh that this angled one gets more of what I would expect the sky reflection is still quite dark considering how bright it was on the inside face of the rear window.

[Erwin Edel]

I also position my buildings on a fairly large circle of terrain to fake a horizon and provide something to reflect at ground level. Perhaps this will help.

Beyond this it would be a matter of playing with the refraction / transparancy settings of your glass surface to get the look you like over the realism of the actual refraction.

I do dial down the strength of the interior light to 50% for daytime renders.

There are also the settings for reflections themselves with a percentage cut-off. You mention that you read another post I made, so I assume you've seen me mention these settings. I generally set the cut off to 0% to get all reflections.

[Emre Senoglu]

it would probably help to have 'something' the windows can reflect, other than the plain sky. in most 3d software you would achieve this by setting an hdri map to the environment. cinerender allows setting hdri for environments too. if you can't figure out how to do this, an easier alternative would be to create a 2d back plate image, behind the camera - so that when you're looking towards the building, the backplate would be behind your back, facing the building.

as erwin mentions, it is a good idea to have a circular ground plane. a full hdri image would typically include a ground too. but if you're using a backplate method, this is a very good idea.

the hdri could be one that's shot in a field, so that on the horizon you see some trees in the distance, or buildings, depending on your context. pretty much the same goes for a backplate image, this can be a row of trees or a hill, etc. you can set this up using a simple wall, or even a curved wall for added effect. find/create a png file with built in transparency, create a material inside archicad, set the transparency setting on, size it accordingly to your wall element, assign it to the wall and you should be good.

[Sam Parish]

Thank you both, I put the HDRi sky in and the lighting still seems to be fine with decent reflections on the windows. I will continue to play with the transparency as the area behind the glass definitely shouldn't be brighter than the area with no glass.

I will keep playing with the options but this is so much closer to what I was attempting.

[Lingwisyer]

I had the same lighting issue in the past, though I do not remember the resolution and I appear to not have posted one if there was... Might have been Daniel's suggestion of reducing Ray Threshold to 1%.



Ling.