Jump to content

Getting some light splotches on high render settings


stayinwonderland
 Share

Recommended Posts

Here's my render:

 

splotches.jpg

 

You'll notice the splotches around the door frames.

 

Settings are the typical render settings, set to quite high. IRR set to medium.

 

LC set to about 1500/2000, noise to 0.005, shadow subdivs around 24, actually set Hsph to 100 to see if that would make a difference.

 

Might not be a render issue, might be something to do with the geometry?

 

Anyways, suggestion welcome!

Link to comment
Share on other sites

First and foremost, check your geometry and make sure all is good. IMO this looks like GI settings gone wrong. First, change the IR Map back to default interp. samples (20) and Hsph (50) and turn off the LC. Try increasing the Interp samples. This will smooth out the solution. Then turn on default LC settings and tweak from there.

Link to comment
Share on other sites

increasing interpolation will "erase" those light circles but you'll lose detail or precision in your GI mostly on small corners, some controls that most people overlook are more important, on Irradiance map you have Color Threshold, Normal Threshold and Distance Threshold, if you fix those before you keep increasing the over all values you'll get better results. Those light bounces can be because the glossies of those doors frames materials. also check there is not gap between your wall and the frames.

Link to comment
Share on other sites

This is tricky. I'm afraid, as time is pressing, I'm having to chicken out of this one and just put curtains there.

 

Increasing interp. samples up to 50 doesn't get rid of them and is a little less accurate/sharp. Tweaking the geometry shows some changes (gaps where the sun is coming through) but then it also shows up in places where the sun isn't coming through.

 

Tweaking the clr threshold seems a little unintuitive. Each tweak costs me minutes before I see a result and I need to get this done.

 

I suspect it's partly due to the gaps between geometry and partly due to something else that might require a full day of click - render - click - render.

 

Thanks for the input though!

Link to comment
Share on other sites

Well that's why Arch viz is part Art and not only Science, the formula does not apply to every occasion.

You can apply a flat color to the whole mesh, and do render region in the problematic areas, I think Distance threshold can help you here more than color Threshold, your moldings are rather small and curves create those strange light bounces. you can activate show samples to check if those are concentrating in the right areas.

 

anyways put curtain is a valid option too :p

Link to comment
Share on other sites

Don't increase the interpolation, You'll lose small details in the GI. Instead what you should do is turn on "detail enhancement" on your irradiance map, it'll increase the detail of your irradiance map around sharp corners & recesses - this almost always gets rid of light leaks for me, even on really low irradiance map settings.

 

You'll also notice an improvement in your GI in other areas because of this too. Also, you could turn on "check sample visibility", which often helps. You have to remember that when VRay interpolates between samples it uses a radius function to decide which ones to interpolate between; this means that if the radius happens to grab a couple of samples from outside, they'll brighten the average of that point thus causing a "light leak".

 

By turning on "check sample visibility" VRay evaluates whether or not there is any geometry dividing the samples that could affect the brightness of them when they're interpolated between.

Edited by Macker
Link to comment
Share on other sites

Client doesn't want curtains...

 

Okaaay, so here's the latest render (just region-rendered the middle portion where the doors are): **view full image**

 

INT-extension_010_glitches.jpg

 

Settings:

 

Camera: f-number 4.0, shutter 80

DMC: 4/12

Reinhard: - burn 0.03 (need to let as much light in as poss without blowing out)

IRR: medium 50/20, detail enhancement on (r = 60.0, subdivs = 0.3), check sample vis enabled

LC: 1500

A/O: 0.6, 0.25m, subdivs 32

Noise: 0.005

 

I cleaned up the geometry and the detail enhancement helped but still getting leaks.

 

Ideas?

 

Thanks for all the help thus far!

 

EDIT: I just increased the sun's photon emit radius from being very small to being as large as the house... that made things much worse.

Edited by stayinwonderland
Link to comment
Share on other sites

IRR 50/20 seems a little low to me, it should be higher, now I don't see much GI problems in other part of the room, so, you may need to review that frame mesh, check if there is not flip polygons, the smooth groups are fine, if so try applying a flat material to it, and see how behave, maybe the glossiness of those moldings or something, Try using brute force in the second bounce, if it render fine then adjust your set up in Light cache

Link to comment
Share on other sites

Ok, the story so far. These renders are 900px but are of the highest settings pretty much:

 

INT-extension_011.jpg

 

Notes: IRR set to high, had to lower the overall exposure as I don't think that was helping (we're talking really low f-stop and burn set to 0.03 which might have been why some of the splotches were so bright). Detail enhancement is on. Still getting some issues though.

 

INT-extension_011b.jpg

 

Notes: This is the exact same render but I selected a region where the main issues exist and rendered with 'store direct light' unchecked and this has made some fairly noticeable difference.

 

My next step is to try rendering a region of a 3000px image and see if that helps.

 

What is kinda weird is that if I change something and that makes it worse, but then I change that one setting back to where it was, it doesn't then return to its previous state, it seems to have an organic nature to it.

 

Also, I rendered a close-up of those areas and they're fine when not at a distance. The material, by the way, is very standard - no glossy effects.

Link to comment
Share on other sites

Seems like we're all throwing in our 2cents, so mine is the Retrace Threshold.

 

Check out example #4 - looks exactly like the problem you're experiencing. Seems to be an issue with the bright exterior + dark interior light cache samples intermixing, throwing off the IMap calculation.

 

Hope this helps.

Edited by matthewgriswold
bright/dark mix-up
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...