Author Topic: Portal placement with complex geometry  (Read 4044 times)

2017-05-22, 16:11:41

Alex.A

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Hi all,

I have a problem placing portals. I was considering placing the portals in front of the windows in the courtyard and front terrace. But after reading some posts it seems that a better solution would be to place them somewhere on the roof and around the front terrace.

However now it seems that such placement will interfere with the spiral staircase and the railings.


Could someone advise what would be a better solution in this situation?

2017-05-22, 17:18:04
Reply #1

maru

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In perfect situation there are no objects between the portal and the environment. So it is more "correct" to place them over the roof than in the window frames, which are slightly more inside of the building.
Also remember that there should not be two portals close to each other - for example in a situation that the light would pass through two portals.

When in doubt it should be also relatively easy to add the portals in both places and then check which option performs better.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2017-05-22, 17:27:13
Reply #2

Alex.A

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Thanks, maru.

I'll try to place a portal over the roof opening, and make some holes in it for the spiral stair. As for the front terrace I'll try covering all the openings.

I'll then compare how it goes with and without portals.

2017-05-23, 18:06:06
Reply #3

Alex.A

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After some tests it turned out that portal were useful in the small windows, the roof windows and the opening. Putting portals around the terrace had the opposite effect - they added more noise.

2017-05-25, 16:03:16
Reply #4

maru

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Interesting. Could you post some screenshots showing various locations of the portals, and the results of those setups? That could be very helpful for other users with similar doubts.
Marcin Miodek | chaos-corona.com
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2017-05-26, 09:16:28
Reply #5

Flavius

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Hi,

Yes please post the tests you've made, I'm struggling with this as well. I always have very difficult/complex geometry for the lighting and placing portals is a true challenge.

Thanks

2017-05-26, 12:46:22
Reply #6

Romas Noreika

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If I have complex building or walls.

for example if I have an L shape window I create an L shape Portal, which I do not know if its correct, but it works.

Sometimes if the portal does not do too much, or not working the way I want. I just put a plane light and pushing a bit more light with it. Straight into the interior.

Think of portals and light planes as a extra help for the engine to concentrate the light samples where you want them.

For example - working for 10 years with vray IM+LC.

Sometimes with detailed classic window frames you get splotches around and in the cracks. When you put a vray light plane in front of it and include only the frame into that light, set it up as a very low intensity just to push more information there - and boom no splotches. Because you just gave your render engine more info to work with.

Of course with BRUTE FORCE we do not have splotches, but lighting wise its almost the same aproach.

Its like interior photographers they put fill lights and stuff everywhere to make the shot right. Because camera is not like a human eye. Its primitive.

And render engines are the same. A lot of things will not work like in a real life. And I will not even mention the render times with some "real life things" :D
RN

2017-05-26, 15:33:01
Reply #7

Alex.A

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This is the portal setup that had the best results for me. There were three additional portals covering the top, bottom and front of the cantilever terrace. Removing each of those helped bringing down the noise a little bit. I haven't tried putting a portal in the window of the terrace though.

Here are the noise results for 20 (or 10?) passes:

all portals                           15.3
no portal terrace front            15.1
no portal terrace front, bottom         14.6
no portal terrace front, bottom, top      14.5


P.S. I also made holes in one of the portals, as you can see in the second screenshot.
« Last Edit: 2017-05-26, 15:45:46 by Alex.A »

2017-05-26, 15:50:00
Reply #8

romullus

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Interesting, did you try to render without portals at all?
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2017-05-26, 16:04:47
Reply #9

Alex.A

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Not quite. However, I was removing the portals one at a time and if the noise increased, I brought that particular portal back in.

2017-05-30, 10:28:40
Reply #10

Romas Noreika

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Just use light plane/shapes instead of portals you will be good. :) Just play with the intensity that is it. Play around with it. And you will get what you want. And also you should get less noise.
RN