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View Full Version : white spots appear whenever HDRI is used



hydrowire
10-04-2004, 11:44 PM
All images below render with Global Illumination, Radiosity.
Images with HDR image as backdrop:
http://www.geocities.com/hidrowire/spot1.jpg
http://www.geocities.com/hidrowire/spot3.jpg

Images with normal JPEG image as backdrop:
http://www.geocities.com/hidrowire/nospot1.jpg
http://www.geocities.com/hidrowire/nospot2.jpg

Why there are white sopts on the object when i use HDR image as backdrop? Am i missing something?
thx in advance!

mattclary
10-05-2004, 05:39 AM
This is actually pretty easy to fix, lets see if I can tell you how to do it without having Lightwave in front of me.... I may not get this 100% right, but you should be able to figure it out based on what I tell you.

In the Image Editor, select your HDRI image, under Processing, load a plugin called... HDR <something>. Can't remember the exact name, but it is the only thing that references HDR. Configure the properties of the plugin. You will have a black level and a white level. One is expressed as a percentage. Set that to something less than 100, I usually use 80%. The other is expressed as number (1 by default). I usually set that to .9 or .8.

Sorry I'm not 100% on this, but like I said, doing it from memory.

hydrowire
10-05-2004, 09:01 AM
thx but...sorry to annoy, it didn't work. I may be missing something but dunno what is it.
Here's a screenshot:
http://www.geocities.com/hidrowire/hmm.jpg

plz help me out!

mattclary
10-05-2004, 09:15 AM
Hmmmm. I would try tweaking those numbers a little, play with it. Always works for me, and I have been using the St. Peter's light probe extensively myself. I do use F-Prime for my radiosity renders (actually, all my renders that F-Prime will support), so that may make a difference.

Exper
10-05-2004, 09:25 AM
You can apply some Blur too in ImageEditor.

hydrowire
10-05-2004, 01:16 PM
nope, useless..
tweaking things here and there, on-off this and that, still the same-the spots remains, clearly. And yes, I tried blur and te result is the same.

surface settings:
Color: 200,200,200
Luminosity:0%
Diffuse:30%
Specularity:35%
Glossiness:40%
Reflection:75%

Image world loaded with an HDR image,
Light: Point, uncheck Affect Diffuse, uncheck Affect Specular, Uncheck Caustics, Check OpenGL
Antialiasing: Enhanced Low
Monte Carlo with Shading Noise Reduction ON

what else i missed??

Sastira
10-05-2004, 01:32 PM
Lower the overall brightness of the HDRI in the image world. Lower it significantly. Most of the time, my image world images are at about 30-50%.

What is your Rays Per Evaluation set to?

toby
10-05-2004, 01:59 PM
Make sure adaptive sampling is off, and LowAA is too low for HDRs, go with medium

My guess is that when you have a pixel with a value that is way above pure white, say, 510 instead of 255, it's impossible to anti-alias that pixel to it's neighboring pixels smoothly - the answer being what Sastira said, or probably what mattclary does when he uses the exposure plug-in.

hydrowire
10-05-2004, 09:50 PM
thank you all for ur time, but..i tweak everything u all said, and still the same-the spots remains, sometimes the spot even have colors~

here's the .lws, go try out.
thx alot!

Exper
10-06-2004, 03:14 AM
here's the .lws, go try out.The archive has no HDR image! ;)

hydrowire
10-06-2004, 07:54 AM
ops, sorry..
i use this: (right click and save as)
http://www.debevec.org/Probes/stpeters_probe.hdr

Exper
10-06-2004, 08:58 AM
ok... I'll give it a try as soon as possible! ;)

caesar
10-06-2004, 11:15 AM
Well, i just loaded your scene and tweaked it a little.
I got this image lowering to 40% the black point in the HDR exposure in image editor.
I see also that increasing the rays per eval. in radiosity is better. Decreasing the black point leave the image a little washed/bright, so experiment with brightness/contrast/saturation in image editor-editing.
The blur in image didnt change much for me in with this setting, and the artifacts are not seen even with no AA.

hydrowire
10-06-2004, 10:29 PM
you guys are great, u all actually go trough my mess and fix it up. a mill' THX!!

but stupid me enough,i still get little spotty! i managed to reduce most spots, but can't archeive caesar's result. caesar, your render looks 100% spot free, i really duno how

so i was thinkin'..caesar, may u send me ur scene file?
im really sry for being annoy..

Exper
10-07-2004, 04:20 AM
caesar beated me on time. :D

hydrowire
the "Blur" is useful mainly for the background.
You can drag it before/after the "HDR Expose" having little different results (give it a try).

Set "HDR Expose" to Foreground
and set the Black Point to a lower value: 50%/40% are good values as caesar already stated (I'm agree).

Then you must grow the Rays Per Evaluation in Global Illumitaion panel (start at 7x24)... you can also use the Interpolated one (more fast).

And make a test Render; you can start using Low AA.

Then you can quite easily play around with HDR Expose and Image Processing values until you'll get the result you want and evetually grow Rays Per Evaluation again.

Take a look a the attach: it includes a fast solution and a slower but secure one... just as a start. ;)

mattclary
10-07-2004, 04:33 AM
Man, if you guys don't have it, you should get F-Prime. I just didn't have to go through all that. I did have to adjust the black and white levels (as stated above, only .8/80%) but didn't have to do any of that other stuff.

caesar
10-07-2004, 08:13 AM
I wish I had Fprime :(. Just a hint: the faster way to me to see results in HDR is simply apply the hdr exposure in image editor and double click the image to open it: in the original hydrowire´file you can see the bright colored spots all messed up. I had to close/open it every time i changed the settings.

Exper
10-07-2004, 08:42 AM
FPrime is really good but you can use HDRI in standard LW quite simply too.
In the previous Post I described a general way to setup it... when you have a little practise then you can go with the HDR probes quite fastly... rendering time is another story!

caesar... maybe I'm misunderstanding... I have no problems in Image Editor using Auto mode.

"Fast" was related to rendering times: using Interpolated instead of Montecarlo!

There are two Scenes in previous attach:
one using Interpolated (8x24) and one using Montercarlo (9x27)... they're modified as less as possible comprared to hydrowire's original one.

@hydrowire: I sent you a P.M.

hydrowire
10-07-2004, 09:49 AM
what can i say?! you guys are great!! Thanks to everyone who help me out.. Finally it works. thanks again!

now, jus one more think, why is the spot happening in the first place? my guess is the HDR iamge is way too bright. as caesar said: *the faster way to me to see results in HDR is simply apply the hdr exposure in image editor and double click the image to open it: in the original hydrowire´file you can see the bright colored spots all messed up.* i was surprise when i double click(i duno this previously) the very white area got messed up with blue green red colour! it was interesting..that explain why my previous render looks potty?

thx for takin' time to read this!

@Exper, thx. i got it!

Exper
10-07-2004, 10:37 AM
I take for granted the Image Editor double click operation... sorry! :D

If you take a look at your scene (the original one) you'll see how the HDRI probe has some bad areas (the bleeding one) and those areas creates artifacts durind the GI evaluation.

You can load the Fast scene and go down to Interpolated (1x3) having good (and even faster) results... higher values are useful for complex and/or hi-res scenes.

Draven
10-27-2004, 04:35 PM
The real trick to get rid of the speckles IS the FP blur (full precision blur) applied in the image editor.

Or, you can blur the original image first in HDRShop or Photogenics.

If you work with HDRI alot, go get Photogenics... Full-precision HDR paint.. http://www.idruna.com

SplineGod
10-28-2004, 12:01 AM
When using HDR Images for lighting purposes you really dont need the full high rez HDRI. You can use a very small version and get great results.

exit6
10-28-2004, 12:23 AM
Sorry, I'm new to this!

mattclary
10-28-2004, 04:57 AM
Here are some to get you started. Supposedly some ship with LW 8, but I've never found them.

http://www.debevec.org/Probes/

mattclary
10-28-2004, 04:59 AM
The real trick to get rid of the speckles IS the FP blur (full precision blur) applied in the image editor.

If you look at the image I posted above, no blur was used.

Exper
10-28-2004, 08:42 AM
I found FPblur useful expecially when they're already balanced and when you have to see them in background.

If a probe has hard edges/spots then FPblur doesn't make any miracle.

Using an HDR painting program is surely more useful cos you can tune up the image finer with less efforts!