Some Lights Refuse to Add Light

waltn3mtj

Some lights I've tried to create don't add any light to my scene. For example, I'm trying to create a series of renders of two women in the front seat of an old car. The camera is looking over the front seat between their shoulders and I'm unable to light their feet as that area simply renders almost black unless Auto Headlamp is active. Auto Headlamp so far has been my best option as I'm unable to create any lights to illuminate under the dash. While Auto Headlamp will eventually render that area with almost acceptable brightness, it takes forever since it has to work so hard to get a half clear render of the dark area: 20 hours+. Very simple scenes with no shadows render much faster....a couple hours at most on the laptop.

I can illuminate the exterior part of the scene fairly well, but nothing inside, not even a Point Source light anywhere you would place a real world light to light under the dash adds any light at all.

Spotlights looking through the side windows (open) light the dash, but not underneath even though I can see what I want to light so shadows aren't an issue by looking through the light's POV. Cranking up the lighting for under the dash doesn't do a single thing to help that I see. Is there a limit to the lights you can add? Obviously under the dash is an important part of realism for the scene plus rendering goes a lot better in bright scenes especially on a computer without a lot of power for rendering. I know I'm missing something likely very simple as I've had DS only a couple weeks now and still scratching at the edges of all it can do while learning.

mjc1016

Can you post a screenshot/render of what you are doing?

Especially noting your light setup.

waltn3mtj

It will be quite a while before I can grab a screenshot as it is in the middle of a render that will take another 12 hours or so on that computer (I'm seeing this one through to completion). I've bumped up the priority of DS so I can't run anything else for risk of upsetting the apple cart since it is taking most of the CPU.

Simply, anything that has high contrast shadows needing a bit of fill like under the dash of a car is what is causing issues. Even simple scenes don't light like I'm used to making happen in my stage and studio work. I know lighting well after over 40 years experience in the field, it is just that DS doesn't behave like those 40+ years experience lead me to expect.

mjc1016

Here's a quick set up....

The lighting is an HDRI and two point lights. 

The first image is the Dome/Environment settings.

The next two are the point light under the dash.

A.  Due to the way Studio has its world coordinate system set up, lights load a little strangely.  It works fine for point/spherical lights, but if you change the geometry (see B) then you need to rotate the light to put the emitting part pointing in the direction you want (in this case down).

B. You can set the geometry for a point light, in this case I chose a rectangular emitter, with the 'long' part of it running parallel to the width of the dash.  I also positioned it slightly below the dash and turned 'Render emitter' OFF (that will hide the 'bulb').  The units for the dimensions are centimeters...

C. Control the intensity with the Luminous Flux, not the intensity slider.   In this case, the default of 1500 was fine at the original default load of the light, but setting the geometry made it too low.  I increased the length of one of the sides of the rectangle, so I upped the value of the luminous flux by the same factor (increase both length and width, multiply the factors and use that for how much to increase the light...it is tied to the area of the emitter).

waltn3mtj

Thanks! I saw advice to turn Environment Mode to Scene Only to get rid of Auto Headlamp, I'll go back to your setting. That is the car I am using with the women figures, but modified for age and neglect (I just changed the paint colors and dulled the paint but would like to find out how to add more effects often found on old vehicles). I also found the copy that installed had translucency turned on for everything, including tire tread which showed ground through the tires! Turning it off for everything that didn't absolutely need it sped up rendering more than I would have believed.

What does the Dome do (If drawing it is a performance hit, I'll have to be careful)? Also, what effect does Environment Map have on the scene?

Thanks for telling me to turn Render Emitter off as in one attempt it did render! I was afraid to try that setting as I didn't know if it would still produce light. I'll set Luminous Flux, then as that is how I think anyway.

mjc1016

Scene only will use only the lights you add...photometric or mesh lights.  That will disable the HDRI/global lighting.

If everything was translucent, it sounds as if the 3Delight shaders were being used/not converted on the fly, properly.   It's better (and usually faster) to use an Iray preset or manually select all the surfaces and apply the Daz Iray Uber shader.

The dome is Iray's inbuilt 'skydome'.  The environment map that is loaded to it is used to calculate 'global lighting'/image based lighting.  There's no penalty for having Draw Dome ON.  If not using a full environment set, it does provide (with a sufficiently large resolution image) a way to provide a background for your scene,  *sufficiently large = pretty much any Hdri 8000 pixels wide or larger.

waltn3mtj

Am I wrong thinking that there is a way to supplement Auto Headlamp with custom added lighting? There are times that it seems automatic lighting works best if I could supplement here and there. That one render I've been talking about is still going on, and is about half done (I turned Render Quality down to 1.5 from 3 as it does make a big difference on that laptop). Also, if I read right, making the scene quite bright and then turning Exposure Value down in rendering will speed things up as there aren't as many dark areas to deal with. If so, that's an advantage the "real world" doesn't have! That area I keep mentioning under the dash is the only area on the render in process that obviously needs work still.

I was very surprised seeing that the chassis and tire treads seemed transparent refracting everything on the other side..... I went through and disabled Translucency on everything as it was turned on right 'out of the box' on my installation (I have to say that a glass running board looked very unique!!). My next goal for the old sedan is to try to mimic the various stages of condition that an old car like that would have today - from pristine and well cared for to beyond practical hope of restoration. I've already dulled the paint and changed colors to some other darker colors popular back then, and am working on a decent looking map for rust patches on the body. I guess there's no way to simulate dents. I have the old pickup truck and the Klunker surface for it. I'm a fan of things from days past and have collected quite a few old scenes and props. But that's another subject, just excited about the flexibility of DS and hoping to master it to get the most out of it.

I've been looking for a way to have a background for my scenes since Bryce and DS don't behave for me. It is nice knowing Skydome doesn't put a hit on rendering. I'm slowly picking up ways to speed up rendering without severe compromises from good hints and suggestions here and experimentation.

scorpio

If you have one area that is taking longer than the rest to clear up, what I do is render that area as a spot render (in new window) and then compose in photoshop or whatever.

waltn3mtj

That's a thought. I've only spot rendered in the editing window and didn't know it could go to a new window like a full render. Time to explore any and all Setup menus!

One suggestion given was to render the background by itself if it will be used unchanged frequently, and then render the foreground, then merge as layers in PP. That should be simple as PNG is easy to work with in this manner. I haven't tried that yet, though.