Rendering in Mantra: Newbie questions.

[Butachan]

Hi!

I recently fully committed myself to Houdini from C4D. Mostly because my first love in 3D was Softimage and when I met houdini was like....but I digress....
I have a few newbie questions that I will greatly appreciate if a more experience user answer them with some honest advice:

• 1. Very confused about GI:
      Is Indirect Global photon map the GI solution for houdini. or the PBR mantra render with multiple diffuse bounces is also capable of GI simulation.
  I ask because the last time I used GI with photon maps was in lightwave with montecarlo calculations (also a bit in C4D before the physical render was implemented) and I remember the horrors of the flickering and bloches and etc etc.  So it really scares me to have to go back to photon maps. I am particularly confuse becaused if the PBR rendering is not simmulating GI. What means diffuse bounces? why Env maps HDR actually illuminates the scene....A clarification of this will be greatly appreciated.
• 2. glass and transparent shadows:
  In most render engines I had used refractions produced transparent shadows. In mantra it seems that this is called (appropriately, I must admit) faux caustic. This solution is quite good enough for me. But 80% of the time I just want the semi transparent shadow, not the higlights and other details caustic cause. Is faux caustic the only way to go in this cases?
• 3. And an important question that I am honestly asking as a newbie with no ulterior motive: is one of the answer "use Arnold (or insert any other renderer)" ? I actually really do like Mantra, the shading tools, noises and integration of custom parameters encourage me. I also mostly do motion graphics, some VFX but nothing that push me to look to an ultra-realistic render (read Arnold). But a good enough GI solution (kind of C4D  physical renderer) is kind of very useful.

Sorry for the lengthy post....oh crap I just made it longer!

 

[lukeiamyourfather]

27 minutes ago, Butachan said:

1. Very confused about GI

Both are solutions to the same problem of rendering GI. Using PBR is unbiased and is the "new" method for GI rendering. It's not quite as fast as using photon caching but it's more reliable and more flexible.

29 minutes ago, Butachan said:

2. glass and transparent shadows

Either use fake caustics on the material or enable path tracing for all paths so you get caustics. Most of the time fake caustics will suffice. Proper caustics are very expensive to render and are not used often.

31 minutes ago, Butachan said:

3. And an important question that I am honestly asking as a newbie with no ulterior motive

Different renderers focus on different things. Arnold focuses on performance and scalability (note it's also biased). You can make pretty images in just about any renderer out there. If you like Mantra and it works for your needs then use it.

[Guest tar]

#2 - you can set Shadow Intensity on the light/shadow tab.

[davpe]

1 - I think using GI in Mantra does not make much sense anymore. Just stick with PBR pathtracer. It's very straightforward.

3 - Both Mantra and Arnold are good renderers. Question to ask is what you expect. My personal point of view of a user that extensively use both products:

With Arnold you will be able to set up render more quickly and it is hard to set it up completely wrong (so wrong that it takes forever to render something relatively simple or you have horrible artifacts). It also comes with a slightly better built basic shading model. More straightforward sampling and displacements. Unfortunately, it also comes with some bad limitations and integration that is not great (no packed prims, shader networks and lighting tools are poor compared to Mantra).

With Mantra you will have to spend much more time to learn it. Many features are sort of hidden or set to odd defaults. At the beginning it overwhelms you with a lot of settings. But if you master it, you'll appreciate it's versatility. Integration is, of course, seamless. Shading networks are insane what it allows you to do procedurally. Really there is nothing else like that in competitive applications. But it goes quite complex very quickly. It's up to you if you even want that. Lighting tools are really good. There is large amount of functionality that allows for a lot of optimizations. Raytrace and Micropoly modes may come in handy if you do non-photoreal renders (or heavy volumes) and you need speed.

 

cheers.

[Butachan]

Thanks very much for the answers. I am definitely less confused about GI in houdini now.

 

9 hours ago, lukeiamyourfather said:

Either use fake caustics on the material or enable path tracing for all paths so you get caustics. Most of the time fake caustics will suffice. Proper caustics are very expensive to render and are not used often.

I think in the last builds I couldn't get the all path tracing method to properly calculate caustics...I had to use faux caustic but like you said its good enough so I didn't mind. I will sometime do a test and send a bug report if in later build the PBR is actually not going through all paths as it says the setting.

 

3 hours ago, davpe said:

1 - I think using GI in Mantra does not make much sense anymore. Just stick with PBR pathtracer. It's very straightforward.

3 - Both Mantra and Arnold are good renderers. Question to ask is what you expect. My personal point of view of a user that extensively use both products:

With Arnold you will be able to set up render more quickly and it is hard to set it up completely wrong (so wrong that it takes forever to render something relatively simple or you have horrible artifacts). It also comes with a slightly better built basic shading model. More straightforward sampling and displacements. Unfortunately, it also comes with some bad limitations and integration that is not great (no packed prims, shader networks and lighting tools are poor compared to Mantra).

With Mantra you will have to spend much more time to learn it. Many features are sort of hidden or set to odd defaults. At the beginning it overwhelms you with a lot of settings. But if you master it, you'll appreciate it's versatility. Integration is, of course, seamless. Shading networks are insane what it allows you to do procedurally. Really there is nothing else like that in competitive applications. But it goes quite complex very quickly. It's up to you if you even want that. Lighting tools are really good. There is large amount of functionality that allows for a lot of optimizations. Raytrace and Micropoly modes may come in handy if you do non-photoreal renders (or heavy volumes) and you need speed.

1.- I will definitely try to avoid using photon maps as much as possible. with moving object they tend to be a natural enemy.

3.- Will have it in mind...now with the posibility of render in a render farm is nice to be able to have that option without the need to buy arnold.

9 hours ago, marty said:

#2 - you can set Shadow Intensity on the light/shadow tab.

Can you do this on a per object level? basically change the shadow intensity projected by one object rather than all shadows from a light?

[Guest tar]

@Butachan it's Houdini. You can do anything you like

Put a IsShadowRay in the shader.  Here it's set to transparent blue.

BlueShadow.hiplc