Iray; 2500x1200 CPU Only 2 days 13 hours 3.6% converged on Current Model Imac Desktop

Patroklos

However, I can't see any difference to how it looked after 7 hours overnight

nicstt

Patroklos said:

However, I can't see any difference to how it looked after 7 hours overnight

Depending on the scene, but from 75% onwards it can get tougher to see, and certainly from 90%; it can be down to smaller areas in shadows, or areas that have a lot of caustics that benefit and need more. I frequently stop 75-85%

Patroklos

but from 0.25% at 7 hours around 470 iterations, to 3.6% at 61 hours and close to 5000 iterations?

I think it looked well finished at 7 hours and around 470 iterations.

There are a few problems. The view during scene construction is very much darker than the render, almost unusably so. In 3delight I would adjust the intensity scale, but that seems to have no effect here. Thats a pity because Iray should be easier to light I would have thought.

Does anyone know how to make such an adjustment? I would be grateful for advice on that.

Patroklos

Got it!

Changing the intensity changes the light in the 3d screen, changing the Luminous Flux changes it in the render!

Patroklos

Works with distant lights, but Point Lights don't seem to light the render at all.

BeeMKay

Can you post your render & light settings?
As for lights, it depends on what setting you use - Dome&scene;, Sky&Sun;, etc.
The lights will do nothing if you use Sky&Sun;, for example.

Patroklos

Hello & thanks for reply,

I will post copy of render settings when I have finished current render.

I am not using sun, I have 3 distant lights switched off and then created a point light to see how it works, - it seems not to work at all.

BeeMKay

What strength are you using for the lights? Normally, it should be at least 50.000 to see a result.

EDIT: Sorry for asking something stupid, but you have downloaded the Iray lights for 4.8, and are using them, not some other lights like AOA lights?

Patroklos

At this moment i am getting what looks like a brightly lit render using 1 distant light on 900 lumens.

You are suggesting that a point light would need a much higher setting?

EDIT I am using the point light at the top of the screne under CREATE, I switch the photometrics on, is this wrong?

BeeMKay

Distant light needs a much lower lumen, like, 10 or 20 max.
Point light needs higher lumen. I'll but some examples together in a minute.

Patroklos

Thank you very much.

I am rather confused by this information as it seems, on the face of it, illogical, and it never occurred to me that where a couple of hundred lumens of distant light would suffice, I should try millions of lumens when using a point light, however I can cope with that.

How do I get the point light to illuminate the 3d screen?

BeeMKay

Okay... a point light is similar to a candle.
Also, you probably have the default HDRI background light giving you some basic lighting.
Make sure that in Camera, under "Parameter", the headlamp is set to "Off". Default is Auto.

Here are two examples of Point light. Please look at the render settings at the right side of the screen.
The first image is Default, at 1500 lms, no other light source.
The second has the point light cranked up to 500.000 lms.

BeeMKay

The next pait is a linear point light. They are basically the same as a point light, but you can adjust certain features in them.
Again, one render at default, one at 500.000lms

What you always have to keep in mind is that in Iray, light behaves like normal light, so it will decay with distance. If you want to lit something far away, you need a stronger light.

BeeMKay

Here's the spotlight pairing, same numbers, default and 500000

BeeMKay

And here's distant light, which is the only light which doesn't decay over distance. So, the object gets hit by the full strengths of the light at 1.500lms. If you dial down the strength to 15 lms, it looks okay.

BeeMKay

And last, but not least, the HDRI default, and the sun-sky setting.

In the sun-sky setting, you can tell the system at what position the sun is standing by using the coordinate and time system (marked in the image).
You can also prop the sun to a light, but that doesn't always get the right results, so I prefer the coordinate-time system, personally.

BeeMKay

Patroklos said:

Thank you very much.

I am rather confused by this information as it seems, on the face of it, illogical, and it never occurred to me that where a couple of hundred lumens of distant light would suffice, I should try millions of lumens when using a point light, however I can cope with that.

How do I get the point light to illuminate the 3d screen?

The question is, why does it have to be the single point light illuminating the entire scene?
Are you woking with a single light source in the middle of a dark room? Then it certainly would be an option, but think about real life. A single light in a room, like a candle, would never be enough to lit everything in the room, but you'd have a lot of dark corners.
That's why normally, you have several light sources in a room if you want to avoid them.
Or is this an outdoor scene? Then using a single point light is not the best approach to simulate sunlight; there's the sun-sky and dome-scene options.
Have a look at the examples in posts 11-15. :-)

The best way to look at it is to study how you would light this in real life.

Patroklos

Thank you, you are a very good teacher!

I take it that point light can be a table lamp, or a ceiling light also?

I would be grateful if you would help me with the sun.

What should I use as the sun? Is it possible to use a distant light?

I have found that Aldoria Sunlight works, are their others?

Finally, the point light does not light the 3d screen, is it possible to change that?

Thanks again!

BeeMKay

Yes, a point light would be good for lamps, etc. You can also use mesh lights (by assigning Iray emissive shader to a surface), but perhaps it is best to start with the simple things first. :-)

okay... for sunlight, you do not need any additional lights in DS for Iray.
First, delete any lights you have in your scene. You can always add more lights later, but for learning, we just use the sunlight from Sun-Sky

Now, locate the "Render Settings" tab (marked with 1 in my picture). Your layout is probably different from mine, but the lavels are the same.
Then, select "Environment" from the list (2).
Click on the small triangle next to "Dome and Scene" in Environment Mode (3).
Select "Sun-Sky Only" as Environment Mode (4).
You can leave most of the settings at default for this first test, but I will quickly explain the most important settings.
First, there is the SS Latitude and Longitude (5). You can adjust the sunlight as it would be for any location on earth with this. Default setting is for Salt Lake City, which is where DAZ3D is located. You can find latitude and longitude information in Wikipedia, btw.
Second, is the SS date and time (6). You can simulate any time of the day during any day of the years with it.
However, if you use this setting, be aware of SS UTC offset (7), which tell the system how the time you set correlates with universal standard time (that's London winter time zone). Default is UTC -6 , the time zone which contains Salt Lake City.

I suggest that you start rendering with the default settings at first. Then, I recommend you try playing around with the time of the day, to see how the light angle changes. Oh, and for test renders, chose a smaller image size first, like 700x500.

Patroklos

Thanks very much for taking the time to explain this!

BeeMKay

No problem. :-)
You can also use the distant light if you don't want to use sun-sky.
Select either Dome-Scene or Scene Only (marked with 1 in the image).
Then, add the distant light.
Select the distant light, and turn down luminescene to 5-15 (see mark 2).
Yu can change the "sunlightcolor" by changing the temperature (see mark 3).
Here's an explanation about the color temperatur, with color chart: http://en.wikipedia.org/wiki/Color_temperature

:-)