Quote - **1. Raytraced shadows
 ** You can do shadows without raytracing

You can do Shadows without raytracing. But they are different.
Without ray tracing you need to do a whole render from each light to build a shadow map. So you need a lot of memory for big szenes to get acceptable shadows. Ray traced shadows don't need that. You don't absolutely need ray tracing for shadows, but ray traced shadows have fewer problems than their scanline counterparts.

Quote - 2. Occlusion
 What do you mean by occlusion?

Ambient Occlusion. Shadows in corners, or other small places. Poser 6 have that.

Quote -
**3. Photon mapping
**Is not a variant of ray tracing?

**4. Monte carlo style GI.
Monte Carlo is used by raytracing

5. IBL
   **I don't know what it exactly does

Image based Lighting. You use a picture to iluminate your szene. It helps a lot if you want to create a 3d-Model which will be copied in a photographed or filmed szenery. You make a picture of a mirror ball, positioned where your model will be. Render your model with the picture from the mirror ball as IBL light and it will fit in the szene.

Poser 6 uses IBL as a method for global illumination.
**
**> Quote - **6. SSS

**This one I don't know what it is

Sub- Surface Scattering. Certain materials (skin, orange juice, wax) do not reflect all light on their surface. Light enters the object and is reflected inside the object. IMHO it is possible to fake SSS without Ray Tracing.
**

**> Quote - **7. Caustics and volumetric caustics.

8. Path tracing for volumetric effects like smoke, clouds etc
   **You can do this without raytracing with expection of correct refraction

Correct. But without refraction it is not easy to get a realistic look.

Scanline is not alwalys faster than ray tracing. If the szenery becomes too complex, or if you have too much lights with shadows, ray tracing is faster. The main professional products (Pixars Photorealistic Renderman and Mental Images Mentalray) are AFAIK comparable in speed - although mental ray only uses ray tracing. Pixars Photorealistic Renderman uses both Scanline (REYES) and ray tracing. So, if you look at the professionals, you can do it without scanline, but not without ray tracing,

Please correct me where I may be wrong, since I am not a professional in this area.

Greetings,
Uwe

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.