Flythrough animation

[sassom]

Hey,

I'm kind of having a problem and do not know how to solve it.

I'm trying to render an animation, about 7000 frames long. It is a fly-through, so no moving objects. It is an architectural animation, contains both interior and exterior scenes, however, the camera movement is continous, flying through the buildings, so I'd like to make it with one sequence. I'm using LC+Irrmap, Brute force would take too long. Due to the interior-exterior scene, I'm using VRaySun and a Dome Light, the dome light is set to "save with irradiance map" to achieve a faster rendering.
I saved the prepasses to file, (used 20000 subdivs for Light Cache, set to Fly-through, every 10th frame, Irradiance map is set to multiframe incremental, Medium-animation, 50 subdivs). When I load the prepasses, and render an interior frame, there are light "patches", mostly at the connection of geometry ("light leaking?"). Although the geometry has no gaps between.







Tried also to render just one interior part, about 400 frames long. LC is set to 5000 subdivs, every 10th frame. The light leaking is still on.

What causes it, and how do I get rid of it?

Thanks you for any suggestions!

[Neilg]

medium animation is for moving objects, use 'medium'.

Whoever wrote that tutorial recently telling people to use medium-animation mode for animations with static objects has now caused 3 threads on here alone with people not getting the right results.

[sassom]

OK, I see. Thanks for the reply! However, I tried different Irradiance map settings, but the light-patches are still present, I don't think it is caused by that. I just wrote that to show that the irradiance map is set to a quite good quality, so maybe it does not cause the problem.

I was wondering, if with LC fly-through method a 7000-frame animation can be rendered in one shot, or I have to cut it in parts, and create separate prepasses for them (I can not increase the Light cache subdivs higher than 65.000).

[Neilg]

does it look ok as a single frame, lc 1500 and IR med? Hows the geometry around those areas - does it have a thickness or is it bright sun on the back face?

[sassom]

Exactly, rendered as a single frame, with 1500 LC the light patches were completely gone (with LC 1000 there were still a few visible).

My terrain has no thickness, and I have these patches mostly at the bottom of walls. I guess that my terrain will need to have a thickness.

But at the attached pictures:
On the second picture, the roof has thickness (although quite thin), which connects to a rather thick wall in the front. I also pusheded it "into" the wall, to intersect the geometry.

The 1st and 3rd picture is a bit more weird, the wall, and the window stones also have thick geometry, crossing each other.

[Companioncube]

in the lightcache have you tried turning on "retrace"? also in LC are you using screen or world sample size?

[Svetlozar Draganov]

The best way to solve light-leaks caused by Light Cache is to use retrace-option like Companioncube suggested.
Sometimes light-leaks could be caused from Irradiance Map - in that case you can use Check Sample Visibility option.

The best practice to avoid such artifacts would be to avoid using objects without any volume.

[sassom]

Thank you all for the answers.

I checked all the geometry to have volumes, but still have some problems. First I used "Screen" mode, now I'm trying "World" and "Retrace threshold" with 1,0 value (also Irradiance map set to and it seems to solve some of the problems, but there are still some light leaks and the quality of the GI is poor. How do I calculate how many subdivisions I will need for the Light Cache for a 7000 frame animation?

Maybe does the subdivision value of the Dome light affect the quality of the Light Cache ? (I left it with 8 subdivs, "Save with irradiance map" option is on)

Also some thinking: if I save the light cache, and load it from file, but the Irradiance map is calculated as "single frame", the light leaks are gone. If I make the precalculations for the IrrMap as well (Medium, every 10th frame), then the light leaks are present, when rendering a single frame (irrmap loaded from file). Does this mean that the lighting errors are caused by the Irradiance map?

[sassom]

* ...also Irradiance map set to Check Sample Visibility...

[Morne]

What units are you using for scene units and what units are you using for display units?

For the VRaySun, make sure that "Shadow Bias = 0.2mm"
If your display units is cm then make "Shadow Bias = 0.02cm"
for meter make "Shadow Bias = 0.002m"

Too large a value for the shadow bias "moves" your shadows. In some cases a large value here wont give any shadows to small objects. In a case like yours it could also cause the shadow to shift too much and that can make it seem like you are having light leaks. I'm not saying that IS the case here, just another suggestion for someting for you to check.

[Companioncube]

Thank you all for the answers.

I checked all the geometry to have volumes, but still have some problems. First I used "Screen" mode, now I'm trying "World" and "Retrace threshold" with 1,0 value (also Irradiance map set to and it seems to solve some of the problems, but there are still some light leaks and the quality of the GI is poor. How do I calculate how many subdivisions I will need for the Light Cache for a 7000 frame animation?

Maybe does the subdivision value of the Dome light affect the quality of the Light Cache ? (I left it with 8 subdivs, "Save with irradiance map" option is on)

Also some thinking: if I save the light cache, and load it from file, but the Irradiance map is calculated as "single frame", the light leaks are gone. If I make the precalculations for the IrrMap as well (Medium, every 10th frame), then the light leaks are present, when rendering a single frame (irrmap loaded from file). Does this mean that the lighting errors are caused by the Irradiance map?

it sounds like the IR map is the problem. your values are quite low, try increasing the HSph. subdivs to something like 80 and the dome light to something between 16-32 and see if that makes any difference at all.