Photometric Point & Spotlights are not rendering in IRAY...

Techyman

I am in the middle of lighting a somewhat complex scene.  I am using the latest version of DS 4.8 and most of my scene is lit using spheres & planes turned into emitters.  The problem I've got is in one specific part of the shot, I need to remove a shadow.  If I use a plane or a sphere emitter, I can't get it close enough to remove the shadow without the emitter being in the shot (which I definitely don't want)  and if I back the emitter out of the shot, the light from it begins to effect other elements in the scene.  A simple photometric point light would solve the problem, but I can't seem to get it to render.  It shows up in preview (texture shaded) but not in the final IRAY render.  I have made sure that the PHOTOMETRIC button is ON and experimented with adding a Photometric Spotlight just to see what would happen.  Again, it shows up in the preview, but not the render.  I have even cranked the lumens up to 50,000 but still nothing.  I checked out some of the video tutorials on YOUTUBE (the ones by Sickleyield are really good), but I still seem to be missing something.

I'm hoping someone here might be able to tell me what I'm doing wrong or at least tell me if there is a way to make an emitter invisible but still emit the light.

Thanks in advance!

ronmolina

I have no problem with the Photometric lights in DAZ with very complex scenes. Look at the drop down for the light and set to a diffrent value. The default will produce very little light the others below the default will produce much more and are more accurate. Try each to see the effect then chose which works for you. Each is calculated diffrently. Further, while emitters are great they do not produce the best results always. Lighting always becomes a critical step and can make or break a pic. I spend more time tweaking lights in a scene than anything else.

Cris Palomino

Try making the mesh light larger; you'll have to play with the settings.  I get good results with a good hdri (not jpg ones) and mesh lights.

Techyman

I really do appreciate the replies, but as I stated above, I can't use another mesh light because, in order to get the effect I need, it would be in the shot (changing the shot is not an option).  If I move it out of the shot and increase the size and/or power, it interfers with all of the other lights I set up and I still get the shadow.  I have tried turning off all the mesh lights and added a point light and a spot light (making sure the photometric button was ON) and experimented with lumens setting ranging from 250 to 5,000,000.  I even put the point light about six inches from a wall. They show up in the preview, but when I render (my engine is set to IRAY) all I get is a black screen.  I then turned on a low set mesh light and rerendered.  The mesh light showed up perfectly, but absolutely nothing from either the point light or the spot.

Here are the settings I'm using:

Illumination:  ON

Color:  255 255 255 (White)

Intensity: 200% (from what I've read, this should not effect a photometric light)

Photometric Mode: ON

Light Geometry: Sphere

Height: 10

Width: 10

Two Sided: Off (also tried it with ON.  No difference)

Render Emitter: ON

Luminous Flux: 25000 (and I made sure the limits are set to off.  This is the current setting.  I have tried 1000 to 5,000,000)

Temperature: 5500

Light Profile: None

I am really hoping that someone can help me.  So far, IRAY has been great.  I love the speed, clarity, simplicity, and stability (even more thatn REALITY 4.1)but I need to figure out this problem in order to make this particular render work.

Thanks again

 

Tobor

Let's address some of the easy-to-fix issues first:

1. You can hide the emitter from the renderer. Turn Render Emitter to Off. (The option might suggest to you that it turns the light off, but it only stops the emitter from showing in the camera).

2. Leave the Intensity control alone. It's correct at 100%.

3. Try a disc emitter first, as it's more efficient. With a sphere or other 3D shape, a lot of the light is being cast away from the direction of your scene.

4. Leave Two Sided off. 

5. Carefully review the other settings: Illumination=On, Visible in Render=On, Visible=On. If any of these are Off, the light will not render.

5. For balancing the lighting, isolate the spot/point by selectively turning off all your mesh emission sources. If you also have an HDRi or sun/sky lighting the scene, choose Scene Only to prevent that light from rendering, and confusing the situation. Don't rely on the Previw Lights feature. That's really intended for placement, not levels.

6. Be sure the camera headlamp is turned off. To do this, make sure you are using an actual camera, and not a "View" (e.g. Perspective). Create a new camera if you have to, and turn its headlamp off. This will prevent its light from influencing the scene, also confusing the situation.

if you continue to have trouble, try a new test scene, with exactly one figure and one point or spotlight. Turn everything else off (dome, sun/sky, headlamp, etc.). Try out the light settings there to get a feel for how they work. Trying to learn everything about Iray lighting in an existing scene can get frustrating. In the end, you'll find it very simple and intuitive.

Techyman

Tobor, thanks for replying so fast and taking the time to give me some really good advice, but I'm still having trouble.

1. Hiding the emitter - I found the render emitter button for the Spot and Point lights, but I can'f find one for a mesh light. I can use a mesh light if I can find a way to keep the light rays but not render the actual mesh.  I'm not sure that's possible. 

On 2,3, and 4 I went with your settings.

For 5, I checked, and all the settings were correct for the point and spot.  

For the second 5, I did that already.  It's basically an interior scene, so I had it set to Scene Only already. 

6. All the headlamps are off (don't really care for them so I use non photometric lights to set up the scene.  I thought these might be messing with the other lights, so I deleted them.  It still didn't work.)  I also did a several simple test scenes (independent of my main scene) with a single figure, a plain wall and floor, and 1 point or spot and I still can't get the Points and Spots to work.  I know they are supposed to and this is driving me a little crazy.

I really appreciate all the help, but I am extremely frustrated right now because several people have told me that they don't have anyproblems using these types of lights.  Everything else in DS seems to be working perfectly.  This tells me that, more than likely, there is something I'm missing and I just can't figure out what it is.  I think I will take a short break so that I can go bang my head against a wall.

As always, I am very open to any suggestions, no matter how farfetched!

Thanks!

 

Tobor

If the test scene isn't working either, then I suspect either a sofrtware issue or a transient memory issue.

1. First check that you are using the latest public release. In Help->About Daz Studio verify you are on 4.8.0.59. If not, download the new version, and be sure to also get the "Default Lights and Shaders for DAZ Studio 4.8+" package.

2. If you are on .59, be sure you installed the Default Lights and Shaders package. It contains important stuff for Iray.

3. Exit D|S and restart your computer, just to make sure there's nothing stuck in memory.

4. Restart D|S, and make sure your active renderer is Iray

5. Start a new scene and recreate your test scene fronm scratch. (Don't use the previous one; start over.) This ensures your cameras and lights are Iray, and not 3Delight.

6. Try it again.

Let us know. If you still can't get the lights to work, you may need to uninstall and reinstall D|S. I'd recommend opening a support ticket with Daz, as if it comes to this, there's clearly something not right with your setup. While you could *possibly* cover up the problem by adding some more mesh lights, that's not the best answer. Mesh lights are inefficient compared to the built-in point and area lights, which are defined inside Iray itself.

(On mesh lights: there's no direct "hide from render" switch, but it can be done. The method is obtuse, but it requires a correct installation of D|S, including that Default Lights and Shaders package.)

Tobor

Because I know you will eventally ask...

To hide any mesh light, do the following steps. I strongly advise you to practive first on a test scene before mucking up a good production scene.

1. Add a human character, such as G2F, so you can see the effect of the lighting.

2. Add a plane mesh 2x2 meters, with just 2 divisions (the fewer the divisions, the more efficient the mesh lighting).

3. Z-Rotate the plane -90, and move it off to the right of the character (camera left). Position it about two meters away. Hint: the preview ground grid is spaced at one meter per division.

4. Select the plane, and use the Surface Selection Tool to select its default surface.

5. Go to the Iray DAZ Uber collection, and double-click on the Emissive surface shader. DO NOT simply dial in the emissive properties based on the generic Iray Uber shader.

6. Then adjust the following:

  * Color Temperature: 6500, unless you want a warmer or cooler tone
  * Luminance: 50
  * Luminance Units: cd/cm^2 (means candles per square centimeter -- I'll mention below why you should select this)
  * Refraction Weight: 1.0
  * Refraction Index: 1.0

Leave everything else untouched, including two-sided (off), and thin walled (on). 

6. Go to My Library/Scripts/Utilities/Create Advanced Iray Node Properties

7. With the plane still selected, double-click this icon.

8. In properties for the plane, locate Display/Enable Iray Matte, and turn On.

Now when you render, the emission surface will be invisible. Renders will likely take a little while longer with this setting.

Important Points: 
A. With the Matte method, the mesh light will still cast a ground shadow. If you don't want it to, skip steps 6-8. Instead, dial down the Cutout Opacity to 0.0001. The plane will be only virtually visible (likely not seen in most situations), and it will not cast a ground shadow. However, it is quite inefficient, and renders will take longer.

B. Changing Refraction Weight to 1.0 will cause the mesh to disappear in preview mode. You can still locate and select it from the Scene tab. If you need to work with your meshes (move, resize, etc.), temporarily change Refraction Weight to 0.0.

Why I use cd/cm^2 for planar mesh lights: This unit selection maintains consistent light output regardless of the size of the mesh. When you use Lumens or Watts, resizing the mesh alters the light output, because the Luminance value is based on overall size. I prefer cd/cm^2, as the centimeter is D|S default scene unit size. Keeps things tidy.

You'll notice that unlike using lumens, which typcally involves huge values because it considers the entire surface of the emitter, cd/cm values are quite small, because they only deal with a small subsection of the mesh. For the purposes of rough comparison, and with planar meshes only, there are roughly 12 lumens per candle at one meter.

Hope you get the issue with scene lights worked out.
   

Techyman

Tobor

I never would have figured out how to hide a mesh light without you!  I'm not going to be able to test this or any of the other advice out until tomorrow, but I am copying your tutorial and will try it out tomorrow.  Thanks again for all your time and patience!

Tobor

You're welcome. The Matte attribute has to be added on a per-object basi, so it's not out in the open. It's something of a "hidden" feature. 

So you know, this isn't the intended use of the Matte setting. It's for a far more involved techniques such as doing in-scene compositing, but it works for a number of other applications, including some kinds of shadow catching..

SickleYield

You can also make a mesh light invisible just by turning its cutout opacity to .001 in the material.  In my testing this has no effect on render time.

Tobor

As I noted in my poist, the barely visible mesh won't cast a ground shadow. Sometimes this is what you want, sometimes it's not.

I think you'll find that on systems not terribly GPU-assisted, the render times are longer with transparency dialed down, as they are with most materials.

Tobor

As this topic comes up from time to time, I posted a quick recap of these methods, plus a third one, here:

http://www.daz3d.com/forums/discussion/62526/quick-howto-making-mesh-lights-invisible-to-the-camera

They all have their places in the Iray scheme of things.

 

Techyman

EUREKA!  Tobor, I redownloaded the Default Lights and Shaders and reinstalled it as per your suggestion.  Most of the files were duplicates, but some weren't.  When I reopened DS and tested it, the Point and Spot lights are now working!  I never would have thought to reload that one file.

THANK YOU!!!!  I can now start getting ready for my final render of this scene!  

PS I'm also looking forward to trying out your techniques for making mesh lights invisible.