ok, being a total newbie with PP2012, if i make the dome invisible to camera and raytracing but leave the light emitter box ticked, does Firefly still use the dome and its image in IDL calculation? 

ie i need the light effect, but want to overlay the render onto a BG of my choosing.

Quote - ok, being a total newbie with PP2012, if i make the dome invisible to camera and raytracing but leave the light emitter box ticked, does Firefly still use the dome and its image in IDL calculation? 

ie i need the light effect, but want to overlay the render onto a BG of my choosing.

Sounds like you want just a plain old image based light, for that you do not need to use a skydome or similar; it does use a different map-type, though.

As for the IDL/2012, i do not know, but why not try it out? Just disable all other lights, leaving only the skydome on and render it, if you get anything lit, it works :-)

Quote - ok, being a total newbie with PP2012, if i make the dome invisible to camera and raytracing but leave the light emitter box ticked, does Firefly still use the dome and its image in IDL calculation? 

ie i need the light effect, but want to overlay the render onto a BG of my choosing.

 

You need to have raytracing enabled for IDL calculation. So set invisible to camera and have the Emit light box ticked. As a texture you can use a texture or material for the environment dome and you can make it grayscale to eliminate color influence

 

 

thankyou!!

I don't understand why you should make a skydome invisible to the camera when a skydome should be large enough to include most camera settings.  Even BB's envsphere is large enough to use for aerial scenes.

Quote - I don't understand why you should make a skydome invisible to the camera when a skydome should be large enough to include most camera settings.  Even BB's envsphere is large enough to use for aerial scenes.

 

because i have few image maps that suit the skydomes, so i want to use the BG images i do have, and layer the render over .

Not sure if this would work for you, but I found that to get reasonable image resolution on a sky dome, you have to go to focal-spot of 35 or something, which for figures falls a bit short of complimentary.

So, I use a panorama (curved) plane displaying the image I want to use as backdrop, and a skydome for lighting. Not ideal but it works.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

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lol! i have trouble with domes anyway, as i tend to use a focal length of 250 on my render camera