HDRI reflection in windows

[Ramon Folguera]

Hi guys,

 

i was wondering. When you do a simple render of a simple 3d model of a building with nothing around. If you place a HDRI in the environment Map slot, so you get nice reflections of sky and good HDRI lighting (with a daylight system). How do you do so you dont get the horizon skyline of the HDRI in the window reflections? (see attached)

 

Thanks,

R

[Nicolai Bongard]

Either you angle your camera upwards so that the windows reflect the sky, or you build an environment around your model that blocks off the horizon line being visible in your render.

[Ramon Folguera]

Thanks,

 

that i know you can do.

 

In my case when it is a quick render study and no context around, Is there any other way? Maybe a different HDRI with only sky all the way to the horizon line?

[Nicolai Bongard]

If you open your HDRI in photoshop and adjust the exposure, you can most likely see that the HDRI will have sky down to the center of the image in the height direction, and that is the horizon. The problem you are having is that your camera is above some of the glass, thus it will reflect things beneath the horizon. Obviously the easy fix is to stretch down the sky in the image in photoshop (MAKE A COPY BEFORE YOU DO), but then you get illumination from the sky from below, and that doesnt make any sense (of course you would get some bounce light from the ground in the real world, but it would be a different color and not as bright). Anyways, a fast way to create a visual blocker for the horizon is to find a horizontally tileable image of a dense treeline with an opacity map, so that you can apply it to a cylinder around your geometry, and thus block the visible horizon. You may want to check out some of the evermotion tutorials/making of`s, as they tend to use this "trick" quite extensively. I will include a link to illustrate: https://evermotion.org/tutorials/show/9845/making-of-sunny-forest-exterior-tip-of-the-week

Obviously they also limit the visibility of this cylinder with more detailed terrain, but it may not be necessary in your case if it is just a quick study with no set context.

[Nicolai Bongard]

Also, you may use a HDRI with terrain included (check out noemotion`s HDRI images, they are free and include the environment.

The problem with that approach is that you will get the terrain visible with no way to scale it (as it is a spherical image), and it may not fit the scale of your scene.

[Ramon Folguera]

I guess the only way then is to visual block the horizon then. With an image or with geometry.

 

Thanks for this Nicolai