Tiny differences between beauty and AOV rebuild

[Andy_Ireland]

Using Houdini 16 on Windows 10, rendering with Mantra PBR, using standard AOV's 16 bit float single scanline compression.

I am using standard shaders no sss/refraction/emission/volume, plussing the AOV's together in Nuke.

There are very slight differences between the rbg values of my beauty and recombined AOV's in Nuke, can see the rgb values in the 2 attached screenshots

Anyone have any ideas why this might happen? Any ideas appreciated, the scene is a comp demo and the differences are confusing me and will confuse the students.

[davpe]

don't take this for granted, but i think such thing could be simply a result of some sort of image processing deviation. i mean having Mantra compositing the beauty pass for you, and then taking decomposed layers and trying to put them together in a different software may not be 100% the same thing (for various reasons), even thou theoretically it is. it would be fun to try and put together the same thing in let's say Fusion and Houdini COPs - maybe you would end up with another two results with some tiny degree of difference?  

[Andy_Ireland]

Thanks davpe, I dont remember this issue with houdini/Mantra before but I also may not have noticed.

Might take a look in Fusion later but I trust Nuke's maths more

[davpe]

well it's not a question of trust, but your answer already presumes that there will be some sort of difference between applications. do you trust Mantra more than Nuke? shouldn't that be the same?