was watching a tutorial setting up HDRI in Houdini but it wasn't done in houdini11. The parameters and materials used seem different but i tried to follow as close as I could.
My render looked grainy and it turned out really dark which was completely different from the tutorial. Anybody has a link related to this topic or knows what I am doing wrong.
Apologies if this is not new to you, I can't look at the .hip right at the moment.
H11 made HDR lighting easier. All you need to do is put down and environment light, and assign the HDR image.
Note the image can't be in Radiance .hdr format - it needs to either be in .exr (an open format) or .rat (Houdini's internal file format). If converting to .rat using Isixpack (Houdini command line tool), ensure the source is in Vertical Cross (cubic map) format.
Seems like your light_dome object is casting shadows onto the teapot. Once it's removed from arealight1's ‘Shadow Mask’ by adding ‘^light_dome’, the teapot does get rendered brightly lit by arealight1.
uniqueloginname - I converted the hdr image to vertical cross using HDR shop & made it .rat. Despite a warning about the resolution, it works when i used it with envLight while “No file or directory” message appeared when used with area light.
I personally prefer light dome method of doing this. Is the environment light is the only way implement image-based lighting in Houdini?
If we're able to use lat/long map .hdr format why would we want to go the extra mile to change it to .rat format. isixpack doesn't allow me to convert lat/long maps .hdr into .rat without first changing it to vertical cross. ._.
tkngs - Hello, I was looking around for a checkbox “Cast Shadow” & “Receive Shadow”. >< This is real different, what does ‘^’ do?
I think it's clear it needs Vertical Cross (cubic) format. I have often ignored the resolution warning, but you can correct it by just adjusting the width or height of the “target” image by 1 pixel when setting up the conversion in hdrshop.
Houdini might have been changed to allow more formats, i.e. HDR, EXR and RAT. Thus converting to RAT might not be necessary these days and Houdini might do it internally like it does with any image in a scene.
It should work with both Environment and Area lights although I don't have much experience with the latter.
Tkngs seems on to the solution (I'm guessing ‘^’ means negation?).
Yes, ^ means ‘NOT’. So essentially, we are telling the arealight1 object to ignore or exclude the light_dome as an occluder when casting the shadow rays.
The Shadow Mask parameter is essentially our Cast Shadow & Receive Shadows equivalent in each light object.
“To create more subtle environment illumination, you can also use a light probe image. Houdini reads environment maps that are set up in the cross format…”
“These files are high definition light probes that can be converted by Houdini’s isixpack reflection map generator utility into rat files. When these files are assigned as Environment maps in the VEX Global Illumination shader then the lighting is derived from image.”
8)
Like I said a few times, maybe things have changed
“To create more subtle environment illumination, you can also use a light probe image. Houdini reads environment maps that are set up in the cross format…”
“These files are high definition light probes that can be converted by Houdini’s isixpack reflection map generator utility into rat files. When these files are assigned as Environment maps in the VEX Global Illumination shader then the lighting is derived from image.”
