Sorry for all the questions lately, I'm trying to learn Poser and come up with new questions on a daily basis, most of them google can help with but not all ;)

Anyway, I'm trying to figure out IDL and am a bit confused. 

Is it mainly used for "outside" setting renders? I have seen some IDL light sets being sold that feature a sphere that iluminates the scene and such...is this mainly for outdoor settings renders?

What If I'm mostly doing portrait shots and indoor shots? is enabling IDL still going to give me better results? Do I need to use the sphere and such for portraitsindoors renders or should I just enable IDL and use my regular lights? (3 point lights, etc)

Is the improvement in indoorportrait renders going to be significant enough to be worth the render time increase?

Any other info you can share on IDL in general would help a lot, thanks! :)

What follows is the Cliff-notes version of War and Peace, as there are volumes of threads about this already. It is the simplist (and over symplified) version I can offer a new user.

IDL stands for "In-Direct Light" and is a mimic for the way light actually behaves.

Using it outside involves using a self-lit dome to mimic the sky in conjunction with a single infinite light to stand in for the sun. Bagginsbill offers a great dome here: https://sites.google.com/site/bagginsbill/free-stuff/environment-sphere for free.

Indoors, the plan most often used is to look and see where light is actually going to be coming from. If there are windows, put the dome ouside over the room set (but put a ceiling on top of the room). If the sun is shining directly into the room, you may have to amp the sun up to 600-800% to get a realistic effect. Put point lights wherever there is a lit lamp, and set them to inverse square falloff in the "Attenuation" drop-down of each light's properties window. 

Overall, lights in IDL only need to be set at 10-20% power as they get reflected and amplified by either the dome (ouside) or the walls (inside).

At render time, many suggest using D3D's Firefly render script located at: Scripts > Partners > Dimension3D > Render Firefly in your Poser install. I have attached a screen capture of the way I run it although many people will recommend other settings to accomplish specific goals. Their answers are "right" too.

If you want to speed things up a bit, set "precalculation scale" to about 50. The quality trade off is minimal.

These are the basics. Give it a try and report back your results and we'll go from there.

It may be a matter of personal preference, but I think IDL is fabulous and a major major emprovement in image realism and quality. Look at the French Quarter Bar image I posted next to your post here, thats all IDL no lights at all except for 1 specular light.

There are no pat formulas for spheres and planes, you just have to experiment to get the look your going for. I have found they need to be quite large to illuminate properly.

little spheres do next to notheing they need to be cranked up to about 800% scale if your using a standard poser ball prop.

After buying pp2012 and using IDL I think it totally eclipses renders done with older versions of Poser, theres just no comparason.

Thanks for the help guys!

One question that I'm still not sure about from your answers is, if I'm doing a portrait render and using just 3 point lights for example, do I still need to use the sphere for IDL to have any effect or can i just turn on IDL in the render settings and leave my regular 3 lights and see better results just from enabling IDL in the settings?

In other words, does IDL NEED the sphere thing, or can it be used with regular "oldschool" lights to good effect?

It can be used with reg lights and often a combination of the two can give good results.

But at the end of the day you really have to experiment, try diffrenet setups to see what looks the best to you, the combinations are endless

Also... IDL requires an enclosed space to work. If your have a room around your character, it will give you the desired resuklts. If the set is in open space, no so much.

Quote - Thanks for the help guys!

One question that I'm still not sure about from your answers is, if I'm doing a portrait render and using just 3 point lights for example, do I still need to use the sphere for IDL to have any effect or can i just turn on IDL in the render settings and leave my regular 3 lights and see better results just from enabling IDL in the settings?

In other words, does IDL NEED the sphere thing, or can it be used with regular "oldschool" lights to good effect?

If the subject is in an enclosed space, you don't need a sphere.  However, if the subject is out in the open, the IDL effect is diminished because there are no surroundings to reflect off of, so use the sphere for outdoors, or something like these freebies will help if it's supposed to be an indoor situation...

http://www.renderosity.com/mod/freestuff/details.php?item_id=23340

http://www.renderosity.com/mod/freestuff/details.php?item_id=70269

You could also use an indoor HDRI image for the sphere...

With IDL you don't need material ambient occulsion, so here's a script to turn it off.

http://www.renderosity.com/mod/freestuff/details.php?item_id=70488

For outdoor daytime renders I use the sphere and a single infinite light.

You wil likely find that you can reduce your normal light intensities by at least 50%.  If there are any unusual highlights in areas that should be shadowed on your figure, you should reduce the IDL intendity in Render Settings.

Have Fun!

I'm not an IDL expert, but if you're doing indoors, I suggest extra lights to make it more realistic, none of us has only one light source at home or where ever you indoors. I've seen IDL indoor scenes that rely on one light source only and they just don't look real.

When mimicking a studio for portraits, I'd suggest having a look at the Poser 8 lights AO or Studio Lights / Studio Lights AO. They're in the lights folder of Poser 8, 9 and the Pro versions 2010 and 2012.

I've found those to give interesting results. You can adjust them, add other lights if you want to. I'm not sure if they work well with IDL, I've only used the without turning IDL on. Experiment, see what works best for you.

And keep in mind, IDL is equivalent to fill lighting providing only diffuse lighting at best.  If you need additional specular highlighting supplementing your key light, you will need to create specular only light sets.

IDL stands for Indirect Diffuse Lighting - so, as has been stated, there is no specular component. As hborre says, it is equivalent to using a fill light in a classic 3 light setup (the others being a main and a rim or hair light), so a very simple setup would be a figure in a surrounding environment (like a sphere) plus a couple of normal lights. I've got a couple of demo's (not tutorials!) of a basic setup in my freestuff which could give you some useful info.

AO stands for Ambient Occlusion; it adds a soft shadowing effect to objects that are in close proximity as if the scene was evenly illuminated (ie. an overcast day). IDL includes an occlusion effect but it is superior in that it changes according to the scene lighting (or, that's my understanding at least). So IDL doesn't need AO on lights or materials - at best it will simply be ignored.

Hope that helps.

Should you use IDL for indoor or in general?

It depends. It is you who decides how to set up your scene.

Do you might like the result of IDL for indoor and outdoor?

Could be.

As said, maybe you like the effect of indirect light.

Exported as obj.  Put two in the scene.  No lights.  V4 in the background.  All the lighting on V4 was from IDL.

I use IDL in all my renders, unless I am doing single-light shadowplay renders where darkness is the main element of the image. in all other scenarios I use IDL at different intensities using the dimension3D dialogue.

When using IDL is worth checking what objects are not subject to diffuse light like ambient and alt diffuse materials. To do this you can run the delete all lights script and run a render (before adding any IDL emittors).