Brazil settings problem.

[Tommy L]

http://www.cgarchitect.com/forum/filepush.asp?file=Up2.jpg

 

Hi everyone,you might say im a tourist in brazil and a bit lost. having trouble getting rid of repeating wierd pattern on a building.The only lighting is an HDRI spherical map background. Materials obviously arnt done yet.

Brazil settings thus far:

Image sampling control: min -3, max 1

GI shade rate: min -2, max 2

Sampling view rate:30 (dont know what this is)

Bounces 2

Sec rate 10 (dont know what this is either)

Render time 'bout 30 mins at 640x480, 75340 faces.

So if anyone has any ideas Id be over the moon. And id tell you how to do the best grass for stills ever.

Cheers, Tom.

[rivoli]

Tom,

one of your problems could be the illumination itself. i mean, a spherical HDR map is much more difficoult to control than skylight. in some cases this is due to the contrasted area of the image. a HDRI is not as a homogeneous source of light as skylight is, and sometimes brazil's QMC samplig gets messed up with HDR images. one trick that you might want to use (in order to attenuate the contrast beetwen different portions of your HDR image) is blur the map. another thing to do is increase the view rate. the view rate is basically the sampling control of your image, it defines the accuracy and precision of tha sampling process. the secondary rate is the same thing, but it controls sampling for reflections and refractions. you might want to check these links where the sampling stuff is explained clearly:

 

http://forums.splutterfish.com/viewtopic.php?t=2315&highlight=sampling&sid=9caf1667ef59f3a4249632592d3959a5

 

http://www.neilblevins.com/cg_education/brazil_undersampling_0_2_26/brazil_undersampling_0_2_26.htm

 

anyway, i'd try this with your image:

apply a blur filter to your HDRI (you can do that whit HDRIshop, at the moment can't remember where to download it)

image sampling control: min.0 max.2

shade rate: min.-3 max0 (this is adaptive sampling, with an appropriate view rate it saves lot of time)

view rate: from 40 to 50 (should be enough)

sec rate: 7

bounces: try it with 1 bounce (if you want your scene more luminous try to increase the RGB level of your map)

 

[ January 16, 2004, 08:08 AM: Message edited by: rivoli ]

[Tommy L]

Cheers mate, Do you use HDRI much? I saw the basilica(?) animation and it seemed like the way forward for light calculations, but Brazil is such a bitch to use im beginning to contemplate going back to dome rigs, spots and omnis.

[moshenko]

Hi Tom,

 

Are you using the public beta of Brazil, or do you have a licensed version? I ask because, with the licensed version, you have access to the Brazil support forums, which are invaluable. Otherwise, you also might want to check out the Splutterfish public forums:

 

http://forums.splutterfish.com/

 

Anyawy, here are some things that might help you out:

 

Originally posted by Tommy L:

 

Image sampling control: min -3, max 1

GI shade rate: min -2, max 2

Sampling view rate:30 (dont know what this is)

Bounces 2

Sec rate 10 (dont know what this is either)

Render time 'bout 30 mins at 640x480, 75340 faces.

So if anyone has any ideas Id be over the moon. And id tell you how to do the best grass for stills ever.

Cheers, Tom.

Your Image Sampling values are pretty diverse, usually it is recommended that they be 1-2 values apart (i.e., -1/1, 1/2, etc.). I would be inclined to stick with the presets: -1/1 for medium quality, 0/2 or 1/2 for high quality. It looks like you've got some artifacts along the thinner objects in the scene, and some of the details are disappearing, which means that you need a higher Max Samples value.

 

You may want to consider lowering your Max shade rate to 0 and bring up the Min rate if necessary. Usually a setting of -3,0 or -2/0 works pretty well.

 

The View Rate and Sec Rate parameters control the amount of samples used to generate GI on diffuse (View Rate) and reflective/refractive surfaces (Sec Rate). Recommended ratio is 3:1, which you've done. You could increase the View Rate to see if the blotchiness improves, but it will be at the cost of slower render times.

 

So, you might find some kind of optimum setting goes something like this:

 

Image Sampling: 0/2

GI Shade Rate: -1,1

View Rate: 60

Sec Rate: 20

 

Your render times are going to increase in order to get rid of the artifacts, unless you are using the licensed version and can throw in a photon-mapped sunlight and reduce your GI bounces to 1 (no regathering). Also, you might want to check the size of your HRDI map - it doesn't need to be very large (256x256 maybe?) and can be pre-blurred to avoid too many samples.

 

Others at the Splutterfish forums can provide much more insight - I'm still in the middle of the learning curve myself.

 

Hope this helps -

 

*rivoli beat me to most of the info! Great advice on HDRI. I need to type faster...

 

[ January 16, 2004, 08:12 AM: Message edited by: moshenko ]

[Tommy L]

Thanks guys. Brazil is forgiven and all is well. 10mins of your time has saved 10 hours of mine.

[moshenko]

Originally posted by Tommy L:

Thanks guys. Brazil is forgiven and all is well. 10mins of your time has saved 10 hours of mine.

Cool!

 

Now, how about that grass... ;D

[rivoli]

Originally posted by Tommy L:

Thanks guys. Brazil is forgiven and all is well. 10mins of your time has saved 10 hours of mine.

well, i'm glad to hear that. i find brazil a great renderer, i'm still trying to learn how to use it, but i'm glad it helped.

 

Originally posted by moshenko:

*rivoli beat me to most of the info! Great advice on HDRI. I need to type faster...

actually i found your advice really helpful, i'll follow it myself.