20,000 Emissive Setting

[broozee]

Per the manual, it said if my emissive layer rendered black, to adjust the intensity. For my scene, I had to set the intensity to 20,000. Why so high?

Regards,
Bill

[dalomar_cg]

Re: 20,000 Emissive Setting

It is due to the exposure settings of the physical camera. Read the Physical Camera settings and that will give you the details on how to adjust it if you need to (F-Stop, ShutterSpeed, ISO). The default camera settings have a very low exposure, so things like emissive materials and HDR background intensities will be very high.

[broozee]

Re: 20,000 Emissive Setting

Ahh! That makes sense - easy enough. Thanks.

Bill

[Shopper2]

Re: 20,000 Emissive Setting

Hi Guys,

I think this topic on the camera needs a little more explanation.

Pretty much every setting in Vray are steps between 1-10 and even with steps of 0.001 to 0.002.
If you're new to Vray then turning on the camera and typing in values like 100000 to get the HDRI map to work is a bit strange dont you think? I guess its doesnt say that anywhere? (or did i miss it)

Thanx for all the help though

Justin

[dalomar_cg]

Re: 20,000 Emissive Setting

Well it is "strange" because the typical mode of thinking is not really "physical", but more or less what is visually pleasing when viewed or created with the computer. I'll throw an example out there. If I have a model with simple GI (no hdr, no Sun/Sky, no extra lighting) color is white and the intensity is 1 with the standard camera (not the physical one), the end result (for an open/exterior model) will basically be whatever the color of the material that I have applied to my objects. As I just explained it, there is no real quality of measuring the illumination of our GI, its "measurement" if you will is to render the pixels as the color of the material, with little influence of the lighting. For the most part the same holds true with lights. Obviously the setup is a bit more involved, but the "multiplier" for lights is basically based on making a pixel render the color of the material that is described.

When you start to introduce the idea of physically based measures of illumination, that whole system that computer graphics has been based off of for years is completely thrown off. Also, at this point in vfr the only illumination that is truely "physical" is the v-ray Sun/sky. Pretty much everything else is not (including HDRS) so it makes it much harder to work when you have some physically based elements and some typical ones.

I agree that this is a bit of a hurdle and kind of counter intuitive, but physically based rendering is the direction that computer graphics has been going on for a while now, and it definitely (in my opinion) produces much better and more convincing results. We want to get everything up to speed with vfr so that we can have lights that use real units and make that whole system of illumination one that works off of physically based values. That way the values are much more realistic and quantifiable.

In the meantime I suggest that you read through the manual and start looking at the system of illumination as something that includes the physical camera. Its something thats overlooked, and you can have just as much control of your illumination levels by adjusting the camera as you can with adjusting the lights. As with every thing its a new tool, and it just takes some time to figure out how to work with it. Once you do I'm sure that you'll find the physical camera very useful