Pathtracer and Default Renderer - Interiors

[Sampdoria]

Hello guys

 

I have been working on the 2 Renderers for a simple Interior Scene.

 

What Id like to know is

 

- How to optimize the Quality vs Time Ratio in both Renderers?

- How to tweak the Original Renderer for dark areas etc. Do I need to tag areas like we used to in Ar3?

 

For example, I believe if I Render an Interior Scene with Sunlight + Lights On, it may take longer than Sunlight only.

 

I really like the Pathtracer but how to resolve the image faster?

 

regards

 

Birdman

 

 

[Roy Hirshkowitz]

You can't do anything to the pathtracer except wait.  Daylit interiors take a long time.  Exteriors and product renderings are usually quite fast.  I'm (coincidentally) working on accelerating daylit interiors using the Path Tracer-- it's going well but it still will be quite slow for some scenes.

 

For the original (Packet Tracer) engine make sure you start with the presets.  That will set things like indirect lighting, ambient lighting, and auto-daylight portals correctly (use glass in your windows).  Judicious use of the "Glossy" shader in the material editor can save a lot of time.  Here's an article on combining daylight and artificial lighting.  Don't tweak.  None of these things currently matter in the path tracer, BTW (they might, by the next build)

[Sampdoria]

Thanks Roy - That explained some things well.

 

What exactly is the Auto-Daylight Portal? Is it to be used with actual sun turned off (to speed up renderings?).

When you say Glossy Shader, you basically mean Glossy properties of materials?

Its good to see that the person providing expertise is also the developer of the software!

 

[Peter Milner]

I think when you select daylight potals, it tells Accurender to concentrate more calculations in those areas so that the image resolves faster. You can run it without any selected but you will have to wait a lot longer for a decent image.

Auto Daylight Portal does what it says on the tin. It automatically detects daylight portals (glass). You still need sun and sky etc on. Be careful though if you have other glass objects or glazed partitioning in your scene as they may also get picked up as daylight portals. I prefer to pick my own.

Packet tracer can be optimized for speed by using simpler materials. Soft reflection and blurry transparency can bring things to a grinding halt. So using the glossy shader for semi-reflective materials really helps.

The Path tracer is best for accurate lighting and complex materials (these hardly affect the speed). It works best when there's plenty of light. Dark shadow areas take much longer to resolve. So in the case of an interior rendering, adding lights can actually speed things up.

[Sampdoria]

That's valuable info. Thanks Peter, I really appreciate it! Peter, as in previous AR versions, does the light calculation and memory get affected by the presence of other objects and lights NOT in the Camera Scene?

 

regards

 

[Peter Milner]

From my experience - yes, though Roy may have a more difinitive answer.

With lights you can of course use channels for different areas and then switch off the ones that aren't necessary for each view.

Also make sure that any multiple objects (5 or more) are blocks so as to utilise the instancing feature. This should help to speed things up.

[Sampdoria]

When you say Multiple Objects, do you mean something like a Light Source (eg Omni) with its' fitting - lets say, 10 of them on a False Ceiling?

 

 

[Peter Milner]

As far as I'm aware, any block repeated more than 5 times is classed as instancing.

This is really handy for me dealing with chairs, desks, computer monitors etc.

Whether or not being a light fitting makes any difference, Roy will have to answer that one.

[Roy Hirshkowitz]

Instancing means that nXt (like AutoCAD) keeps only a single copy of a repeating block in memory and just records its location and orientation in the scene.  This can save a lot of memory.  It's somewhat slower to process things this way, so nxt does have a threshhold before instancing kicks in (I think Peter's correct-- the threshhold is 5 instances.)

 

Blocks containing light sources are not instanced.  

 

*****

 

On a separate note-- my investigation of daylight sources in the Path Tracer is not going so well-- I'm probably abandoning them.  OTOH, I have been able to accelerate the convergence of glossy surfaces lit by daylighting without he problem we encountered with frosted glass.

[Ros. Riha]

Please, how can I tag a window in AutoCAD Architecture to behave as Daylight portal to speed things up?

[Peter Milner]

I think you'll need to use the auto option where glass objects are automatically selected as daylight portals (it's in the advanced tab of the lighting palette).

[Marc Chaumier]

True Peter, the lack of light is the longer to resolve. In outside render to. So If I got not enough time, I put always the sun in my back... but the light's effects are less interesting.

[Ros. Riha]

cannot wait for the next build ... sounds very promising