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Posted by hansmex at May 22, 2010 8:40:39 PM
Imperfect rendering
Emmanuel:

While testing various new features I (more or less) completed this project. Below is a render using the new "standard" advanced rendering.

There are a few problems:
- there is a blue hole in the roof; this was also visible in a test-render using the "old" standard photo feature.
- the top of the roof is too bright; maybe the "sun" is too low (or close) in the light calculation?
- the shadows underneath the porch are too dark; this resembles a bit the darkness of an interior that is lighted only with sunlight. Maybe the shattering of light by the dust in the air is not taken into account? This kind of extreme shadows is what you would expect on the Moon, not on Earth.

Hans




Posted by fhoofman at May 22, 2010 9:36:31 PM
Re: Imperfect rendering
can it be more like a photo quality?

Posted by db4tech at May 23, 2010 4:24:36 AM
Re: Imperfect rendering
As I discovered, while trying to create very soft shadows from a large light source, by making a beauty dish (two dishes with a very bright light inside) out of a reflective umbrella model that Emmanuel kindly made for me to test. In the rendering process a light rays path is only being calculated once, after the ray has hit a surface it disappears, so light bouncing (scattering) isn't happening.

This might be the same reason your buildings entrance is appearing dark, because the light isn't being reflected back off the ground to help provide some fill light?

Here is the beauty dish model.


How it renders. I used Uber this time but all photo and advanced photo renders appear the same (from a light point of view) The frame at the side isn't illuminated by the light, the frame is a shiny surface and reflecting the illuminated dish.



I have written this next part to try and explain (for those who don't know) the effect of putting a single light source inside a beauty dish makes.

Since a single small distant light source will always cause objects to produce dark hard edge shadows (like the Sun does on a clear day) Putting a single light source inside a beauty dish. (by the way no direct light rays can hit an object from a beauty dish, only reflected light) The light rays bounce around the surfaces several times before finally exiting in multiple directions creating the effect of a much larger light source, because the light rays then hit the object from different controlled angles, the light rays overlap each other causing the same object to cast softer edge shadows as the light wraps around the objects surface, as can be seen here. Image produced in Art of Illusion.


Of course rendering the paths of multiple light rays and their surface interactions requires intensive calculations, producing much slower (final photo) rendering times.

db4tech

Posted by Puybaret at May 23, 2010 6:31:07 PM
Re: Imperfect rendering
db4tech, I found where this wrong effect comes from.
I would be glad to publish a plug-in with the fix but there's still a problem with sunlight that doesn't reflect on walls. sad
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Emmanuel Puybaret, Sweet Home 3D developer

Posted by Puybaret at May 24, 2010 7:52:42 PM
Re: Imperfect rendering
there is a blue hole in the roof
Could you check if this hole appears in version 2.2 too?

the top of the roof is too bright
The shininess set on the roof object must be too high. You should edit the MTL file of this object and reduce its Ns and Ks values.
Caution: don't change the color of the roof afterwards because changing the color of an object sets its shininess to 64 (shininess may have a value between 0 and 128).
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Emmanuel Puybaret, Sweet Home 3D developer

Posted by db4tech at May 24, 2010 9:03:26 PM
Re: Imperfect rendering
Hi Emmanuel,

I am also seeing holes in the roof of other models, they are present with all three rendering plug-in's Advanced photo, Phong and Uber.

I was thinking of calling the builders to fix the roof but then thought I'd best let you see it first smile



PS: I'll cover the grey leaves in the other forum thread.

db4tech

Posted by Puybaret at May 24, 2010 11:35:11 PM
Re: Imperfect rendering
I'm quite sure this wrong rendering and Hans' one, is miserably due to a problem in the rendering process of SunFlow. In version 2.2, it ended up to infinite loops; I fixed the infinite loops problem but sometime holes appear instead now.
I really don't master SunFlow source code yet... sad
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Emmanuel Puybaret, Sweet Home 3D developer

Posted by db4tech at Jun 12, 2010 4:25:30 PM
Re: Imperfect rendering
db4tech, I found where this wrong effect comes from.
I would be glad to publish a plug-in with the fix but there's still a problem with sunlight that doesn't reflect on walls. sad


Hi Emmanuel,

With you now working on Sweet Home version 2.5, is this something that could be added (even though sunlight doesn't reflect) or is it something to add to the shader plug-in's?

If it is a shader addition, knowing that renders will take longer to calculate, will you be able to add a render quality slider (like the inbuilt photo render) so a user can choose to render with or without indirect illumination?

Having indirect illumination (even without sunlight reflection) with maybe only 1 or 2 ray bounces will make a dramatic effect, further enhancing the realism of final renders.

I am very happy to test this for you! smile

One last request, when you do finally replace the inbuilt render with one of the advanced renders please keep the most basic render (like the inbuilt Create photo... Fast render) I find this setting very useful (creating an almost instant render) to see what will appear in a final render when trying different camera positions, angles and aspect ratios, before doing a full render.

Thank you for your time.

Hope you are having a great weekend!
db4tech

Posted by Puybaret at Jun 20, 2010 9:51:27 PM
Re: Imperfect rendering
The "hole" bug Hans mentioned at the beginning of this thread will be fixed in the coming version 2.5, with this bug and that one related to rendering too. smile
You can test the correction in the version 2.5 Beta 7.

db4tech, managing reflection can be done in the plug-in itself and I'll try that after the release of version 2.5.
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Emmanuel Puybaret, Sweet Home 3D developer

Posted by Puybaret at Jun 22, 2010 12:21:05 AM
Re: Imperfect rendering
Version 2.5 with the bug fix was released on June 21, 2010.
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Emmanuel Puybaret, Sweet Home 3D developer

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