.Exr Hdr backgrounds


(Dark Minaz) #1

Hey

I tried making a new hdr for my scene
but it fails every time to process

Are there some guidelines or tips on how to get them to work?
@james or anyone that might know :slight_smile:


(Mrchlblng) #2

hey @dark_minaz,

we indeed have issues in our environment processing and we do not keep data from those failures at the moment. Could you send us an exr that fails processing? Thanks a lot!


(Dark Minaz) #3

GreenRock.exr (1.6 MB)

sure thing :slight_smile:
this one isn't finished but i just wanted to know if it somehow works

right now it's just a finished hdr with a color change but i though id try it before i spend hours on photobashing/painting my own together


(Cedric) #4

Hi,
I just checked your environment and it seems to contains invalid pixels. Invalid pixels are rgb channels that contains:

  • negative values
  • NaN ( not a number )
  • -Infinity / +Infinity

if I try to clamp value to range 0:65535, I have a the result you can see in in the green picture

test.exr (1.5 MB)


(Dark Minaz) #5

ah now it works.
alright so i need to make sore none of my values is negative or anything, alright ill try to learn hdr stuff today and how to make a good one then :slight_smile:

thanks


(Cedric) #6

Yeah it's better to keep values 'valid' . On our side we will improve to have the same behavior you have in photoshop or other hdr viewer.


(Dark Minaz) #7

As long as i know why it doesn't process correctly i can fix it :slight_smile:
i just never really knew what to look out for since no program ever gave me a bad reply


(Shaderbytes) #8

What are you using to represent hdri pixel values in the shaders , half float? Do you perform any luminance shift?


(Cedric) #9

The processing tools uses the float data to compute the spherical harmonics data for diffuse part of lighting and an cubemap and a panorama texture are created for the specular.

Each step of calculation is done in float/double but at the end in the panorama/cubemap we store float value encoding in 8 bits luv format to keep precision.

You can get some informations about luv https://mynameismjp.wordpress.com/2008/12/12/logluv-encoding-for-hdr/ but there are also may other resources on the web.


(Dark Minaz) #10

@cedric
can you tell me how to do that whole "clamp" thing
tried to find an answer with google but that seems impossible to find

test2.exr (1.8 MB)
finished painting mine and i can't seem to figure out if it got negative values or anything but it won't work so i assume it does :stuck_out_tongue: