faking caustics

I have been playing with yafray. its a nice render, but slow as hell:(
Blender internal render is faster.

now i hear that you kind fake stuff in blender. how can you fake caustics?

throught a clear bottle with vegitable oil in it.

thanx in advance

If you are using caustics (raytracing in general) a lot this is not yafrays fault, but the problem lies in the method (i.e raytracing is slow) And you don’t know this is faster in the blender internal renderer because caustics to not exist there.

now i hear that you kind fake stuff in blender. how can you fake caustics?
I don’t know a way to fake caustics with other methods (no matter of what render engine you use) but if there is one (i dunno, maybe a baked glow texture or something like that) i think a lot of people would like to hear of it :wink:

Werner

http://denko.maxarea.com/tutorials/tut02.htm

it’s max specific but some blender pro can have a look and give pointers on converting it

That’s a pretty cool tutorial, thanks for the link :slight_smile:

But it doesn’t really help in the case the OP is looking at. There we have focused (or concentrated) caustic effects rather than a ‘global’ pattern. See e.g here: http://www.deviantart.com/deviation/18235813/ or http://www.deviantart.com/deviation/18449033/ (random examples, there are a lot more out there)

The concentration of light is defined (exactly) by the geoemtry (here: a bottle) that causes it (think: magnification lense in the sun).

Werner

Wait untill you see how “fast” is Maxwell or Indigo. :wink:

It’s all about the method the render uses…unbiased engines are simply totally different from something like Yafray, so, it’s almost not possible to compare them.

Anyway, why would you fake caustics? Blender’s Internal engine is good and will probably be even better with Material / Render nodes but for something like caustics I’d still advise to use Yafray or any other Render engine that supports it. Faking is good but when you need a lot of time to get it right and you have the option to do the real thing, why wouldn’t you do it?

I personally think that it’s just more accurate if the rendering engine calculates it for you and if you want to achieve high realism then you have to accept long render times, I fear :wink:

Why fake it if it would be possible? … Easy: If the light source and the transparent object do not move the whole scene/movie then you would only need to do it (e.g the real caustic render) once and then ‘bake’ it … instead of rendering it every time/frame. Ona that would reduce rendertime a lot :wink: … but i’m just babbling since i never made my own movie … not to speak of one with caustics in it.

Werner

Of course, when we’re talking about animations, I get the point. I probably should have added that I was talking about stills.

Either way, I sadly can’t come up with anything useful for animations either. But I’ve searched the forums and there were quite some threads with similar titles found, so, consider to do a little search on the problem, maybe something works out for you?!

cool

I have been playing with yafray. its a nice render, but slow as hell:(
Blender internal render is faster.

I stand by that statement Blenders internal render is faster.

Hoehrer,

If you are using caustics (raytracing in general) a lot this is not yafrays fault, but the problem lies in the method (i.e raytracing is slow) And you don’t know this is faster in the blender internal renderer because caustics to not exist there.

I did not say: Blender has caustics

Hoehrer

I don’t know a way to fake caustics with other methods (no matter of what render engine you use) but if there is one (i dunno, maybe a baked glow texture or something like that) i think a lot of people would like to hear of it :wink:

I am not sure what lover affair you have with yafray; to think just cause yafray(raytracing ) exists their are no work arounds for blender internal.

I am tied of spending 2 to 24/hrs rendering caustics in yafray just to find out I need to tweek the lighting, material etc for 5min. Just to have my computer spend the rest of the day rendering. Only to find out there is more tweeking to do:mad:

Do not get me wrong I like yafray. I have spent part of this summer learning it. But I have put it aside “out of frustration” looking for work arounds. http://blenderartists.org/forum/showthread.php?t=70187

MassTA

Wait untill you see how “fast” is Maxwell or Indigo. :wink:

As I said, I am looking for work around caustics if there is one? I am not saying yafray is the slowest render to maxell or indigo etc. I do not care about that.

The purpose of this thread is find out if there is a work around caustics because yafray is slow. I do not want to spend hours waiting for a render. In the right hands, using work arounds blender, artists have used internal render to produce stunning results. Check this out http://blender.org/cms/Images.151.0.html;) :wink:
Thanx in advance

here is a blend I made some time ago, with some fake caustics I made the original and some one else did the tracking Darg I think. the light texture is not the best but it could be improved very easily.
http://www.upload2.net/page/download/GWorsI2xYYMuvVd/FAKECAUSTIC_MOVING.blend.html
http://img147.imageshack.us/img147/5174/ctest6tc.jpg

And I didn’t say you said that :wink: but you can’t compare functions/features (in this case the speed of causic-rendering) that exist in in one program and are nonexisting in the other … if you get my point.
And faking something can then done in any rendering engine you like, since the faked feature is ‘skipped’ even if it’s there. But that’s beside the point of the thread as you already mentioned :wink:

I don’t even use yafray that much, I’m just stating that it (mostly) isn’t a matter of the engine, but the features you use in your scene.

I will not go into a discussion about test-renderings … if you render everything complete and in full-quality all the time you sure as hell will render this scene until the heat-death of the universe … and it may be caused by your CPU running hot :wink:
<sarcasm>Welcome to the wonderful world of 3D art. Nothing is easier to do.</sarcasm>

Ok, time to get serious again:
I’m sure other ppl have better tips for a faster test-render workflow, but here are some basic suggestions to reduce render-time when test-rendering:

  • Try reducing the size of the rendered image.
  • Render only parts of the scene (different camera with smaller size … you might need another scene for easy usage)
  • Remove (move to other layer) geometry from the scene you don’t want to see while adjusting materials/lights/etc… for something completly different.
  • Reduce or turn off OSA [1]
  • Turn off AO/GI [1]
  • Turn off caustics if you tweak materials or once they look good.
  • … etc Generally only leave the things in that you want to tweak, and you only need to do a full render of the whole scene once (if you are lucky) or twice.

Just speaking in examples there :wink: Since the OP didn’t mention what he’s rendering (single scene/animation) i assumed it to be the more time-consuming animation ;).

As I said, I am looking for work around caustics if there is one? I am not saying yafray is the slowest render to maxell or indigo etc. I do not care about that.

I think the blend file shr1k posted looks very promising, but i haven’t look into that yet.

Werner

[1] not quite sure how this is handled in yafray, but i think setting things to “None” in the “YafRay GI” (Global Illumination ~ Ambient Occulsion … IIRC) will work wonders to your render-time :wink: … if they are activated that is.

Thanks Shr1k:)
That is what I am looking for possible work arounds to yafray’s caustic.

Hoehrer

…but i’m just babbling…
—really:rolleyes:

If you have a work around to caustic lets hear it.
otherwise Quit posting junk

<Junk>
Sorry that i can’t offer a solution because i haven’t found one myself [1] yet. And i’m also sorry i even tried to help you with the slow rendering issues you mentioned when adjusting your scene. I suspect i’ll just delete all my posts from this thread then since it’s junk anyway.

Werner
</Junk>

[1] But others have:
http://www.linuxgraphic.org/section3d/blender/pages/didacticiels/blender_material/tp1-5-ang.html (Blender)
http://www.3d-resources.com/3d_studio_max_tutorials/fake_caustics_tutorial.html 2 (Max)

Thanks guys, here goes. My first attempt at faking caustics. The first image is blender internal render the other is yafray.
The here objective is to get a fake caustic close to yafray caustics. Why you might ask-- to reduce render times. blender internal ~11sec; yafray ~12min

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