Isotropix Forums

Using textures to control AA samples with overscan

General Discussion about Isotropix and CG related topics

Using textures to control AA samples with overscan

Unread postby bvz » Fri Feb 12, 2021 8:40 pm

Hello,

We use input textures for controlling our AA samples quite extensively. Now we are starting to do a fair bit of rendering using overscans. Is it possible to control the AA samples of the overscan area using a texture? If so, how would I do that?

Thanks!
bvz
 
Posts: 78
Joined: Tue Dec 03, 2013 9:55 am

Re: Using textures to control AA samples with overscan

Unread postby aaute » Mon Feb 22, 2021 2:11 pm

Hi,

In order to be able to control the AA in the overscan area you need to have a texture dealing with the texture outside of the current area.
For procedural texture like fractal you don't have to do anything. If you have a map or map files you can play with the repeat mode (repeat or edge). I suppose your texture is most likely a constant.

Cheers
Aymeric
Isotropix
Technical Artist - Clarisse Specialist
User avatar
aaute
 
Posts: 45
Joined: Mon Nov 02, 2020 11:59 am

Re: Using textures to control AA samples with overscan

Unread postby bvz » Tue Feb 23, 2021 4:35 am

Thanks.

Actually our textures are not constants. We have a setup where we use textures to selectively boost the AA samples in parts of the scene. For example, we may have buildings with flat faces but complex roof tiles. We will then create a mask where we isolate these roof tile areas. Inside the mask area we may boost the AA samples to 64 whereas outside of the mask the AA samples are set to 16 samples (for example). This mask is animated over the course of the shot so as to always (and only) represent the area where the roof tiles are.

We also use masks to drop the samples to 0 where there is no geometry, effectively reducing render times on frames/shots where the bulk of the frame is empty (but still would otherwise fire a full suite of AA sample rays into each pixel).

All of these steps go a long way to speeding up renders while maintaining quality at an acceptable level (especially important on 8K square 60 fps renders).

None of these masks seem to work outside of the overscan area. We cannot use repeat or reset because that just becomes a constant color and has no relationship to the actual information in the overscan area.

Seems like when we have overscans we cannot use these techniques and will have to modify our camera/render settings to do an actual render of the overscan area - unless you have an idea how else we might get this kind of detailed masking in the overscan areas?
bvz
 
Posts: 78
Joined: Tue Dec 03, 2013 9:55 am

Re: Using textures to control AA samples with overscan

Unread postby aaute » Tue Feb 23, 2021 11:08 am

Hi,

I did a test with overscan and it's working. I attached the project if you want to take a look.

You need to be sure that the image you apply on the AA texture have the information of the overscan in it.
For example if I have a 1080p with 50px overscan on every side, and i output an image 2020 x 1180 straight from photoshop, Clarisse will fit the image in the HD resolution and doesn't take in consideration the overscan.
If I take the same image and process it in Nuke with a HD reformat (resize none, center and preserve bounding box).
Image

Save it and apply it to my texture in Clarisse you are going to have the correct result.
Image

Cheers
Attachments
AAoverscan.7z
AA ovesrcan test
(9.53 KiB) Downloaded 2 times
Aymeric
Isotropix
Technical Artist - Clarisse Specialist
User avatar
aaute
 
Posts: 45
Joined: Mon Nov 02, 2020 11:59 am

Re: Using textures to control AA samples with overscan

Unread postby bvz » Tue Feb 23, 2021 10:19 pm

Oh excellent. Thanks.

I will explore that.
bvz
 
Posts: 78
Joined: Tue Dec 03, 2013 9:55 am


Return to General Discussion