Backgrounds

[Jon Berntsen]

How do you achieve crisp, nice, high res backgrounds in renderings? I'm using two HDRi dome lights, one for light and one for background. But the problem is that even if I load the HDRi light with a 20k texture, the light itself can only be put to 8192 resolution. It's very convenient having the background in a dome light, as I don't have to think about the background when doing several camera angles.

[Stephen Thomas]

Maybe you could try the sIBL script? That brings in all your maps (background, lighting, reflection) and has them wired to a sphere's rotation so you can easily line it up in your scene.

 

sIBL-GUI

[Francisco Penaloza]

But how sharp you want your backgrounds needs to be??

they are in the back... physically they should be a little out of focus, because your main object is guiding the focus of the camera.

 

20K is pretty large already. not sure why is not looking 'sharp' enough to you.

 

in my little time in post production for TV and similar, to create large backdrops, they didn't rely in a single image. Resolution problem will be always there with a single image, you need to build your background out of large resolution planes, several of them.

For instance trees, buildings, mountains, sky and others. all of them can be separated large resolution images, arranged to align with the camera.

You should try that if you need to have sharper objects in your background. or use 3D geometry.

look for tutorial of environment creation on NUKE or FUSION, there they explain how they build those set extensions and backdrops.

[Chris MacDonald]

But the problem is that even if I load the HDRi light with a 20k texture, the light itself can only be put to 8192 resolution. It's very convenient having the background in a dome light, as I don't have to think about the background when doing several camera angles.

 

The resolution setting on the light is misleading and has nothing to do with the resolution of the HDRI displayed in the background. The background will still display at full (so 20k for you) resolution.

 

Most HDRI's come with multiple backplates to be added in post for high resolution shots. That said a 20K HDRI should be more than enough(!)

[Jon Berntsen]

The resolution setting on the light is misleading and has nothing to do with the resolution of the HDRI displayed in the background. The background will still display at full (so 20k for you) resolution.

 

Most HDRI's come with multiple backplates to be added in post for high resolution shots. That said a 20K HDRI should be more than enough(!)

 

I don't exactly know the field of view, but somewhere around 120 degrees should be right. Then take 360/120 = 3. That means, the resolution at 20 000/3 = 6666. So then it should be crisp and clear. But it isn't. It's pixelated and nowhere near what I see from hi end exterior imagery elsewhere out there. Changing backplates per image is not an option IMO. I need to be able to do two different angles without searching for a new a separate but similar backplate for each of them.

 

I thought of draping a texture inside of a sphere, if the light texture resolution were the problem. Are you sure that the Res parameter in the VrayDomelight isn't connected to the Texture? It seems so in the GUI. It's a tiny bit cryptical in the documentation:

Res – Specifies the resolution at which the texture is resampled for importance sampling.

If you're correct, then using the sphere method won't do anything good.

 

We've got the whole bunch from VP, but they're actually just big enough to be rendered with 2500px width, which we (or anybody else) never do.

 

Chris, what do you do for backgrounds/skies?

[Jon Berntsen]

But how sharp you want your backgrounds needs to be??

they are in the back... physically they should be a little out of focus, because your main object is guiding the focus of the camera.

 

20K is pretty large already. not sure why is not looking 'sharp' enough to you.

 

in my little time in post production for TV and similar, to create large backdrops, they didn't rely in a single image. Resolution problem will be always there with a single image, you need to build your background out of large resolution planes, several of them.

For instance trees, buildings, mountains, sky and others. all of them can be separated large resolution images, arranged to align with the camera.

You should try that if you need to have sharper objects in your background. or use 3D geometry.

look for tutorial of environment creation on NUKE or FUSION, there they explain how they build those set extensions and backdrops.

 

Building backgrounds with several images, I can understand the need for that. Might end up as a solution, even though I'd like to have the final solution into a hemispheral texture. Maybe just working with a very high res spherical image (improving the hdri's that we already have). Scaling up and inserting /cloning in pieces from the 100% version.

[Chris MacDonald]

I don't exactly know the field of view, but somewhere around 120 degrees should be right. Then take 360/120 = 3. That means, the resolution at 20 000/3 = 6666. So then it should be crisp and clear. But it isn't. It's pixelated and nowhere near what I see from hi end exterior imagery elsewhere out there.

That's very odd given that such a large image should be so pixelated. Is it because you're rendering out at a crazy high resolution, so the render looks considerably sharper?

 

I thought of draping a texture inside of a sphere, if the light texture resolution were the problem. Are you sure that the Res parameter in the VrayDomelight isn't connected to the Texture? It seems so in the GUI. It's a tiny bit cryptical in the documentation:

 

If you're correct, then using the sphere method won't do anything good.

 

"back in the day" people used to use a blurred/low resolution hdri/jpeg as the source image for their lighting, and a higher resolution, sharper one for the background - that is basically what VRay is doing internally.

 

We've got the whole bunch from VP, but they're actually just big enough to be rendered with 2500px width, which we (or anybody else) never do.

 

Chris, what do you do for backgrounds/skies?

 

I use the CG-Source skies and rarely have to do anything with them to make them sharper. Do you have an example of what result you're getting? Even if it's just a 100% crop.

[Francisco Penaloza]

I also wonder what you mean with not sharp enough.

Coming back to my first post, it will be very hard to do what you want, one single dome light solution. That's why I explain what other pro artist do. Their output was 10K or more to be used for films so we are talking big size stuff, the one you see on TV or theaters and never question if it is sharp enough, besides too sharp images make it look fake. Even photographers that over sharp their images make them look fake.

 

When you use HDRI to lit your scene, the default workflow will use the same image to lighting, reflections and background, but you can separate all those and adjust the size or quality accordingly. I am pretty sure you already manage that.

 

If you show some sample of someone else work I am pretty sure that they replaced the background in post, because that's the best way to control quality. If you go to Evermotion for example they use planes, with not that height resolution as background images and they look pretty good.

 

I can't remember the name of the company now, but they sell HDRI for Cars and product visualizations, and they sell high resolution panoramas and backdrop matching exactly the camera position. It should not take that long if you use a set like that one to replace in post your backgrounds.

If it is an animation, that's different, on large production they still will use NUKE or Fusion to make the whole thing in layers and passes, for us arch viz, a dome with a height resolution image will do or change in post.

 

Also you need to consider, when you create an spherical panorama, all the pixels are used on the image, so let say you have a plain site, with a tree line about 1 Km distant from the camera, those tree will only use maybe a 1% of the total pixel of your camera output? so if you have the newest camera shooting 50 Mega pixels, those tree will use very little pixels of the total. you'll need an insane size of panorama with several shots per degree to get a 50 mega pixels tree line, you'll run out of ram very easily and the antialising of VRay will be crazy trying to process that amount of data for lighting and reflection purposes.

 

Jut replacing the background with one still image in post is way more officiant if you are concern of the quality of your backgrounds.