HDRI Background Question

Banti

Hello everyone,

i have a question regarding HDRI and Backgrounds. Is it possible to use the lights from and HDRI with a different Background? Say, i want to have a (jpg) picture of a forrest that i want to be visible when looking out of

a window in my scene. Can i still use a HDRI to light my interiors somehow?

 

Thank you

Richard Haseltine

Turn off Draw Dome in the Editor tab of Render Settings and you can put any background image behind the scene, either using the Environment pane in DS or saving the render as Tiff or PNG so that the background is left transparent or you get a mask channel you can use to float the image (depending on how your software handles alpha channels) and layering the render on top of a photo - the latter is more flexible but less immediate.

JonnyRay

Banti said:

Hello everyone,

i have a question regarding HDRI and Backgrounds. Is it possible to use the lights from and HDRI with a different Background? Say, i want to have a (jpg) picture of a forrest that i want to be visible when looking out of a window in my scene. Can i still use a HDRI to light my interiors somehow?

Thank you

As Richard points out, it's certainly "possible". Just be careful and make sure the light from your HDRI is aligned with the lighting of the backdrop you're using. For example, if the backdrop looks like the light is coming from behind the camera, so the shadows are falling away from the point of view of the one who took the picture, then make sure your HDRI isn't casting light toward your camera or it's going to immediately look off somehow even if your viewers can't tell you why.

Also see the tutorial I wrote that linked in my signature for the pros and cons of the background options in Daz Studio.

Random

It's too bad some very smart person can't yet figure out how to combine the virtues of IRAY with those of a sky dome.

Catherine3678ab

Random said:

It's too bad some very smart person can't yet figure out how to combine the virtues of IRAY with those of a sky dome.

They did. And some very smart people bought it too.

https://www.daz3d.com/iray-worlds-skydome

 

L'Adair

Banti said:

Hello everyone,

i have a question regarding HDRI and Backgrounds. Is it possible to use the lights from and HDRI with a different Background? Say, i want to have a (jpg) picture of a forrest that i want to be visible when looking out of

a window in my scene. Can i still use a HDRI to light my interiors somehow?

Thank you

@Banti, Adding to what Richard and JonnyRay said, and referring to the specific question you posed:

• An HDRI cannot light an enclosed interior. But you can use an HDRI if you open up that interior. Experiment with hiding the ceiling or one or more sides of the room that are off camera, (not in the frame.)
• Depending on how far away the scene of your forest is, "physcally" in the scene, or visually in the photo, you can sometimes get away with the shadows going the wrong way for a background that is viewed from a window. It's not uncommon for the artificial light inside a room to have different angles than the sun outside.
• When using a prop for the background, such as a plane with your image applied to the Base Color parameter in the Surfaces > Editor, or one of the older multiplane cyclorama props, be careful of having the light behind the prop, as it will cause an unnatural shadow on the ground. Watch for that in a test render. It might not be an issue when viewing the prop through a window, but will more than likely be a problem if the entire scene is outdoors.
• And a tip for using either a plane or the multiplane cyclorama props with Iray: In the Surfaces > Editor, use the Base Color image in the Emissive Color parameter and set the color to white. (This turns on Emissive and using white won't interfere with your image's colors.) Set Emissive Temperature to 0.00, so it also doesn't color your image. Change Luminance Units to kcdm^2. You will then adjust Luminance to a value that will bring out the colors of your image without actually lighting the scene. I've set Luminance as low as 1.0 and as high as 50.0 to achieve that goal, so it really depends on the image.

@Random, Besides Iray Worlds Skydome, there is the Iray Skydome Super PAK., and other addons from Magix 101. However, when Iray first came out, some "really smart people" figured out how to use the skydomes created for 3Delight with Iray. Here's the thread with the best solution, imo, "Yet Another Iray Skydome Technique". Will gives the recipe in the OP, (original post.) He adds an addendum toward the end of the thread, too.

Banti

Thanks everyone for your help. I didnt event think about turning off the dome, i dont know why ^^
Anyway, i very much appreciate all the help and tipps, thanks again