Terragen made HDRI creating ultra bright pixelated spots!

[AcesHigh]

Ive created some nice Terragen HDRIs, both in cubic and spherical formats. They load beautifully as background, and in HDRI programs (like HDRShop), they work very well, changing exposure, etc.


But when I load these Terragen HDRIs into VRAY, the image is very dark (even if I set the GI multiplier at 50!), but on the other hand, there are tons of ultra bright pixelated spots all over the image... as if there was a mirror globe on the sky with white lasers pointing at it! Really weird!

Any idea whats the problem?


01
from the ground


02
from above, but close


03
from above, very far away (cant even see the ball anymore. Notice the artifacts pattern REMAIN THE SAME, its constant, no matter the distance!!!!

[sepo100]

Re: Terragen made HDRI creating ultra bright pixelated spots!

Saw this On SCF. I can try it for you in LightUp to see if it works subject of course that you upload it somewhere.

[AcesHigh]

Re: Terragen made HDRI creating ultra bright pixelated spots!

I saw your message on SCF...

I downloaded LightUp Demo... no artifacts appeared when I loaded the HDR image.

BUT... I do not think LightUp really uses HDR. You can SELECT HDR images as skybox, but the way LightUp uses the HDR to light the scene is the same way it uses a simple JPG to light the scene... I guess LightUp loads the HDR at default exposure and then lights up the scene as if the HDR was a simple JPG.

Anyway, no artifacts in LightUp.

[dalomar_cg]

Re: Terragen made HDRI creating ultra bright pixelated spots!

This is typically a GI caustics issue. Disabling both reflective and refractive GI caustics in the Indirect Illumination rollout should take care of that for you.

[thomthom]

Re: Terragen made HDRI creating ultra bright pixelated spots!

Do you know what usually causes it? Extra bright pixels?

[dalomar_cg]

Re: Terragen made HDRI creating ultra bright pixelated spots!

I'm really not sure exactly what's causing it. Its one of the few "mysteries" that I've yet to solve. The really odd thing about it is that the artifacts resemble that of errant photons. Since photons require a real light source, and the environment maps aren't a light source, its even more odd that photons would be emitted.

For a while I actually thought they were part of the default light, which would explain the errant photons, but for some reason it isn't related to it.

I think it would be hard for really bright pixels to end up in an hdri. The reason being is that the brightest pixel will only be as bright as the brightest pixel in the brightest exposure. Since the brightest exposure that's used to create an hdri has the pixels so burned that they simply report the "maximum" intensity that they can record. A pixel could potentially be brighter, but the camera just can't capture it.