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does the size of the dome matter when using HDRI? I mean... if I make a bigger dome, does it lower the light intensity or is it the same?

Thanks

definetly, size matters...

Light intensity is derived from the mxi image data therefore no i dont think so. Also the light shouldn't falloff over distance only after bounces should the intensity or whatever descrease.

hmm i see your point, however you can't change the intensity of an mxi using the emitter w's settings so it would have to be adjusted through the mxi viewer to effect the scene dramatically. All depends on your scene whether you could get away with using a small dome or not.

thanks for the replies guys..

Adam: and yes.. it would be easy to find out... but who doesn't have a render going with maxwell?

plus.. in order to try this out correctly we would have to let all bounces finish... or maybe... this is a question: would leaving the same scene, but diff dome size and aborting lets say at 10 samples do the trick to test this?

me too. I have some images in the maxwell oven. I will do some tests later.

Yes, size matters.

I have exagerated the sizes of the half spheres, and there's diferences.
Tonight I'll post some results.

I'll guess the shadows will be different. I also think final quality depends on the spheres' construction and how its polygons are arranged around the sphere (number of and shape) The above tests, when posted, should clear the ?'s up though.

If you think about it a larger dome will effect the scene in that it's light will directly reach more of your scene. Points of the dome that did not reach when the dome was small are more likeloy to reach these points when using a mcuh larger dome.

as per simple diagrams



& larger dome

philipbruton,

It doesn't quite work like that for a sphere envelope. You need to take into account that there are numerous points around the perimeter that contribute to illumination (not just a single point).

In case of a sphere envelope (I suspect) the math works counter to what is expected and the illumination should be constant regardless of size...
1. Each illumination point on the surface of a larger sphere is further (larger radius) from the center but there is more surface area contributing to the scene.
2. Each illumination point on the surface of a small sphere is closer to the center but there is less surface area contributing to the scene.

... which is contrary to this example where the illumination sphere is outside the scene-->

http://www.maxwellrender.com/forum/view ... 898&#41898

This is what i meant, obviously i know there is more than one point, one point was used to decribe the effect from any one of the given points on the dome's surface, hence a greater surface area effecting the image as u said.

Model by jotero



At first sight it seems they are the same but.... compare elephant's head ,elephant's back, floor, intensity.......

PS: Thanks jotero for share these models with us